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Sample records for archetypal heisenberg pyrochlore

  1. LETTER TO THE EDITOR: Magnetic ordering in Gd2Sn2O7: the archetypal Heisenberg pyrochlore antiferromagnet

    NASA Astrophysics Data System (ADS)

    Wills, A. S.; Zhitomirsky, M. E.; Canals, B.; Sanchez, J. P.; Bonville, P.; Dalmas de Réotier, P.; Yaouanc, A.

    2006-01-01

    Low-temperature powder neutron diffraction measurements are performed in the ordered magnetic state of the pyrochlore antiferromagnet Gd2Sn2O7. Symmetry analysis of the diffraction data indicates that this compound has the ground state predicted theoretically for a Heisenberg pyrochlore antiferromagnet with dipolar interactions. The difference in the magnetic structure of Gd2Sn2O7 andof nominally analogous Gd2Ti2O7 is found to be determined by a specific type of third-neighbour superexchange interaction on the pyrochlore lattice between spins across empty hexagons.

  2. Spin-Ice State of the Quantum Heisenberg Antiferromagnet on the Pyrochlore Lattice.

    PubMed

    Huang, Yuan; Chen, Kun; Deng, Youjin; Prokof'ev, Nikolay; Svistunov, Boris

    2016-04-29

    We study the low-temperature physics of the SU(2)-symmetric spin-1/2 Heisenberg antiferromagnet on a pyrochlore lattice and find "fingerprint" evidence for the thermal spin-ice state in this frustrated quantum magnet. Our conclusions are based on the results of bold diagrammatic Monte Carlo simulations, with good convergence of the skeleton series down to the temperature T/J=1/6. The identification of the spin-ice state is done through a remarkably accurate microscopic correspondence for the static structure factor between the quantum Heisenberg, classical Heisenberg, and Ising models at all accessible temperatures, and the characteristic bowtie pattern with pinch points observed at T/J=1/6. The dynamic structure factor at real frequencies (obtained by the analytic continuation of numerical data) is consistent with diffusive spinon dynamics at the pinch points. PMID:27176537

  3. Low-temperature Spin-Ice State of Quantum Heisenberg Magnets on Pyrochlore Lattice

    NASA Astrophysics Data System (ADS)

    Huang, Yuan; Chen, Kun; Deng, Youjin; Prokof'ev, Nikolay; Svistunov, Boris

    We establish that the isotropic spin-1/2 Heisenberg antiferromagnet on pyrochlore lattice enters a spin-ice state at low, but finite, temperature. Our conclusions are based on results of the bold diagrammatic Monte Carlo simulations that demonstrate good convergence of the skeleton series down to temperature T = J/6. The ``smoking gun'' identification of the spin-ice state is done through a remarkably accurate microscopic correspondence for static spin-spin correlation function between the quantum Heisenberg and classical Heisenberg/Ising models at all accessible temperatures. In particular, at T/J = 1/6, the momentum dependence shows a characteristic bow-tie pattern with pinch points. By numerical analytical continuation method, we also obtain the dynamic structure factor at real frequencies, showing a diffusive spinon dynamics at pinch points and spin wave continuum along the nodal lines.?

  4. Spin-Ice State of the Quantum Heisenberg Antiferromagnet on the Pyrochlore Lattice

    NASA Astrophysics Data System (ADS)

    Huang, Yuan; Chen, Kun; Deng, Youjin; Prokof'ev, Nikolay; Svistunov, Boris

    2016-04-01

    We study the low-temperature physics of the SU(2)-symmetric spin-1 /2 Heisenberg antiferromagnet on a pyrochlore lattice and find "fingerprint" evidence for the thermal spin-ice state in this frustrated quantum magnet. Our conclusions are based on the results of bold diagrammatic Monte Carlo simulations, with good convergence of the skeleton series down to the temperature T /J =1 /6 . The identification of the spin-ice state is done through a remarkably accurate microscopic correspondence for the static structure factor between the quantum Heisenberg, classical Heisenberg, and Ising models at all accessible temperatures, and the characteristic bowtie pattern with pinch points observed at T /J =1 /6 . The dynamic structure factor at real frequencies (obtained by the analytic continuation of numerical data) is consistent with diffusive spinon dynamics at the pinch points.

  5. Spin-Lattice-Coupled Order in Heisenberg Antiferromagnets on the Pyrochlore Lattice.

    PubMed

    Aoyama, Kazushi; Kawamura, Hikaru

    2016-06-24

    Effects of local lattice distortions on the spin ordering are investigated for the antiferromagnetic classical Heisenberg model on the pyrochlore lattice. It is found by Monte Carlo simulations that the spin-lattice coupling (SLC) originating from site phonons induces a first-order transition into two different types of collinear magnetic ordered states. The state realized at the stronger SLC is cubic symmetric characterized by the magnetic (1/2,1/2,1/2) Bragg peaks, while that at the weaker SLC is tetragonal symmetric characterized by the (1,1,0) ones, each accompanied by the commensurate local lattice distortions. Experimental implications to chromium spinels are discussed. PMID:27391746

  6. Spin-Lattice-Coupled Order in Heisenberg Antiferromagnets on the Pyrochlore Lattice

    NASA Astrophysics Data System (ADS)

    Aoyama, Kazushi; Kawamura, Hikaru

    2016-06-01

    Effects of local lattice distortions on the spin ordering are investigated for the antiferromagnetic classical Heisenberg model on the pyrochlore lattice. It is found by Monte Carlo simulations that the spin-lattice coupling (SLC) originating from site phonons induces a first-order transition into two different types of collinear magnetic ordered states. The state realized at the stronger SLC is cubic symmetric characterized by the magnetic (1/2 ,1/2 ,1/2 ) Bragg peaks, while that at the weaker SLC is tetragonal symmetric characterized by the (1,1,0) ones, each accompanied by the commensurate local lattice distortions. Experimental implications to chromium spinels are discussed.

  7. Field driven phases in the geometrically frustrated dipolar Heisenberg pyrochlore antiferromagnet Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Enjalran, Matthew; Del Maestro, Adrian; Gingras, Michel J. P.

    2008-03-01

    The rare-earth pyrochlore gadolinium titanate, Gd2Ti2O7, represents an excellent experimental realization of a Heisenberg antiferromagnet (AFM) in a frustrated geometry with weak long-range dipole-dipole interactions (approximately 20% of nearest neighbor AFM exchange). Experiments on Gd2Ti2O7 in a magnetic field reveal a complex phase diagram associated with the breaking of spatial symmetries of the pyrochlore lattice as the field is applied along select symmetry directions. We study a model of classical Heisenberg spins (O(3) symmetry) on a pyrochlore lattice with exchange and dipolar interactions within mean-field theory. Using parameters relevant to the material system, we develop phase diagrams in finite magnetic fields. Our results our compared to experiments on Gd2Ti2O7 (and Gd2Sn2O7).

  8. Order in the Heisenberg pyrochlore: The magnetic structure of Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Champion, J. D. M.; Wills, A. S.; Fennell, T.; Bramwell, S. T.; Gardner, J. S.; Green, M. A.

    2001-10-01

    The rare-earth pyrochlore material Gd2Ti2O7 is considered to be an ideal model frustrated Heisenberg antiferromagnet with additional dipolar interactions. For this system there are several untested theoretical predictions of the ground state ordering pattern. Here we establish the magnetic structure of isotopically enriched 160Gd2Ti2O7, using powder neutron diffraction at a temperature of 50 mK. The magnetic structure at this temperature is a partially ordered, noncollinear antiferromagnetic structure, with propagation vector k=121212. It can be described as a set of ``q=0'' ordered kagomé planes separated by zero interstitial moments. This magnetic structure agrees with theory only in part, leaving an interesting problem for future research.

  9. Low-temperature specific heat and possible gap to magnetic excitations in the Heisenberg pyrochlore antiferromagnet Gd2Sn2O7

    NASA Astrophysics Data System (ADS)

    Del Maestro, Adrian; Gingras, Michel J. P.

    2007-08-01

    The Gd2Sn2O7 pyrochlore Heisenberg antiferromagnet displays a phase transition to a four sublattice Néel ordered state at a critical temperature Tc˜1K . The low-temperature state found via neutron scattering corresponds to that predicted by a classical model that considers nearest-neighbor antiferromagnetic exchange and long-range dipolar interactions. Despite the seemingly conventional nature of the ordered state, the specific heat Cv has been found to be described in the temperature range 350mK⩽T⩽800mK by an anomalous power law Cv˜T2 . A similar temperature dependence of Cv has also been reported for Gd2Ti2O7 , another pyrochlore Heisenberg material. Such behavior is to be contrasted with the typical T3 behavior expected for a three-dimensional antiferromagnet with conventional long-range order which is then generally accompanied by an exp(-Δ/T) behavior at lower temperature where anisotropy effects induce a gap Δ to collective spin excitations. Such anomalous T2 behavior in Cv has been argued to be correlated to an unusual energy dependence of the density of states which also seemingly manifests itself in low-temperature spin fluctuations found in muon spin relaxation experiments. In this paper, we report calculations of Cv that consider spin-wave-like excitations out of the Néel order observed in Gd2Sn2O7 via neutron scattering. We argue that the parametric Cv∝T2 does not reflect the true low-energy excitations of Gd2Sn2O7 . Rather, we find that the low-energy excitations of this material are antiferromagnetic magnons gapped by single-ion and dipolar anisotropy effects, and that the lowest temperature of 350mK considered in previous specific heat measurements accidentally happens to coincide with a crossover temperature below which magnons become thermally activated and Cv takes an exponential form. We argue that further specific heat measurements that extend down to at least 100mK are required in order to ascribe an unconventional description of

  10. Archetypal Criticism.

    ERIC Educational Resources Information Center

    Chesebro, James W.; And Others

    1990-01-01

    Argues that archetypal criticism is a useful way of examining universal, historical, and cross-cultural symbols in classrooms. Identifies essential features of an archetype; outlines operational and critical procedures; illustrates archetypal criticism as applied to the cross as a symbol; and provides a synoptic placement for archetypal criticism…

  11. [Dreaming archetypes].

    PubMed

    De Angelis, Elio

    2009-01-01

    The Jungian notion of archetype is compared with the one developed by Ernst Curtius, also derived from Jung. Both notions are seen against the background of modernity--that both authors identify with Nazism--thus highlighting the ambiguity and potentiality embedded in Jung's original thought, generally neglected in later developments.

  12. [Dreaming archetypes].

    PubMed

    De Angelis, Elio

    2009-01-01

    The Jungian notion of archetype is compared with the one developed by Ernst Curtius, also derived from Jung. Both notions are seen against the background of modernity--that both authors identify with Nazism--thus highlighting the ambiguity and potentiality embedded in Jung's original thought, generally neglected in later developments. PMID:20695399

  13. Archetypal healing.

    PubMed

    Jones, D; Churchill, J E

    1994-01-01

    With emphasis on healing versus curing, the authors draw from a wide assortment of treatment methods for psychospiritual relief of pain in the terminally ill. These archetypal methods include: life-review therapy; ministry of presence; clinical hypnosis; myths, symbols, rituals, and community; creative therapies. In life-review therapy, the ill person shares his/her life story with the provider much like the healing rituals of the ancient storyteller did in his community. In the ministry of presence, the caregiver focuses on sharing his vulnerability, not his professional skills. Clinical hypnosis emphasizes the naturalness and simplicity of accessing the unconscious along with problem areas of the hypnoclinician. Myths, symbols, rituals, and community serve as nurturing agents in the intervention of pain, while creative therapies such as music, drama, crafts, and art continue to be powerful healing instruments. Archetypal healing produces relief of pain in the caregiver, as well as the ill, with emphasis on healing versus curing. PMID:8117487

  14. Magnetic Orders and Fluctuations in the Dipolar Pyrochlore Antiferromagnet

    NASA Astrophysics Data System (ADS)

    Cepas, Olivier; Shastry, B. Sriram

    2005-03-01

    While the classical Heisenberg antiferromagnet on the pyrochlore lattice does not order, we will discuss, from a theoretical standpoint, possible magnetic phases induced by the dipole-dipole interactions. Such interactions play a role in systems such as Gd2Ti2O7 or Gd2Sn2O7 in stabilizing exotic forms of magnetic order, a subject of current debate. We will also argue that the external magnetic field induces multiple transitions, one of which is associated with no obvious broken symmetry, but can be characterized by a disorder parameter. Finally, Monte-Carlo simulations and Landau-Ginzburg expansion show that the dipolar Heisenberg model exhibits a fluctuation-induced first-order transition, thanks to the frustration and a continuous set of soft modes.

  15. "The Odyssey" as Archetype

    ERIC Educational Resources Information Center

    Lowery, Alice M.

    1970-01-01

    Suggests the relevance of The Odyssey" to the lives of 20th century adolescents in exemplifying two fundamental archetypal themes: initiation and man's search for his own identity and for meaning in life." (Author/RD)

  16. Archetypes for Organisational Safety

    NASA Technical Reports Server (NTRS)

    Marais, Karen; Leveson, Nancy G.

    2003-01-01

    We propose a framework using system dynamics to model the dynamic behavior of organizations in accident analysis. Most current accident analysis techniques are event-based and do not adequately capture the dynamic complexity and non-linear interactions that characterize accidents in complex systems. In this paper we propose a set of system safety archetypes that model common safety culture flaws in organizations, i.e., the dynamic behaviour of organizations that often leads to accidents. As accident analysis and investigation tools, the archetypes can be used to develop dynamic models that describe the systemic and organizational factors contributing to the accident. The archetypes help clarify why safety-related decisions do not always result in the desired behavior, and how independent decisions in different parts of the organization can combine to impact safety.

  17. Approaching archetypes: reconsidering innateness.

    PubMed

    Goodwyn, Erik

    2010-09-01

    The question of innateness has hounded Jungian psychology since Jung originally postulated the archetype as an a priori structure within the psyche. During his life and after his death he was continually accused of Lamarckianism and criticized for his theory that the archetypes existed as prior structures. More recently, with the advent of genetic research and the human genome project, the idea that psychological structures can be innate has come under even harsher criticism even within Jungian thought. There appears to be a growing consensus that Jung's idea of innate psychological structures was misguided, and that perhaps the archetype-as-such should be abandoned for more developmental and 'emergent' theories of the psyche. The purpose of this essay is to question this conclusion, and introduce some literature on psychological innateness that appears relevant to this discussion.

  18. Approaching archetypes: reconsidering innateness.

    PubMed

    Goodwyn, Erik

    2010-09-01

    The question of innateness has hounded Jungian psychology since Jung originally postulated the archetype as an a priori structure within the psyche. During his life and after his death he was continually accused of Lamarckianism and criticized for his theory that the archetypes existed as prior structures. More recently, with the advent of genetic research and the human genome project, the idea that psychological structures can be innate has come under even harsher criticism even within Jungian thought. There appears to be a growing consensus that Jung's idea of innate psychological structures was misguided, and that perhaps the archetype-as-such should be abandoned for more developmental and 'emergent' theories of the psyche. The purpose of this essay is to question this conclusion, and introduce some literature on psychological innateness that appears relevant to this discussion. PMID:20883307

  19. Heisenberg's First Paper

    ERIC Educational Resources Information Center

    Cassidy, David C.

    1978-01-01

    Describes some of the discussion, correspondances and assumptions of Heisenberg. Includes clarifying and defending his explanation of the anomalous Zeeman Effect to the Quantum Physicists of his time. (GA)

  20. Heisenberg's observability principle

    NASA Astrophysics Data System (ADS)

    Wolff, Johanna

    2014-02-01

    Werner Heisenberg's 1925 paper 'Quantum-theoretical re-interpretation of kinematic and mechanical relations' marks the beginning of quantum mechanics. Heisenberg famously claims that the paper is based on the idea that the new quantum mechanics should be 'founded exclusively upon relationships between quantities which in principle are observable'. My paper is an attempt to understand this observability principle, and to see whether its employment is philosophically defensible. Against interpretations of 'observability' along empiricist or positivist lines I argue that such readings are philosophically unsatisfying. Moreover, a careful comparison of Heisenberg's reinterpretation of classical kinematics with Einstein's argument against absolute simultaneity reveals that the positivist reading does not fit with Heisenberg's strategy in the paper. Instead the appeal to observability should be understood as a specific criticism of the causal inefficacy of orbital electron motion in Bohr's atomic model. I conclude that the tacit philosophical principle behind Heisenberg's argument is not a positivistic connection between observability and meaning, but the idea that a theory should not contain causally idle wheels.

  1. Archetypes as action patterns.

    PubMed

    Hogenson, George B

    2009-06-01

    The discovery of mirror neurons by researchers at the University of Parma promises to radically alter our understanding of fundamental cognitive and affective states. This paper explores the relationship of mirror neurons to Jung's theory of archetypes and proposes that archetypes may be viewed as elementary action patterns. The paper begins with a review of a proposed interpretation of the fainting spells of S. Freud in his relationship with Jung as an example of an action pattern that also defines an archetypal image. The challenge that mirror neurons present to traditional views in analytical psychology and psychoanalysis, however, is that they operate without recourse to a cognitive processing element. This is a position that is gaining increasing acceptance in other fields as well. The paper therefore reviews the most recent claims made by the Boston Process of Change Study Group as well as conclusions drawn from dynamic systems views of development and theoretical robotics to underline the conclusion that unconscious agency is not a requirement for coherent action. It concludes with the suggestion that this entire body of research may lead to the conclusion that the dynamic unconscious is an unnecessary hypothesis in psychoanalysis and analytical psychology.

  2. Archetypes as action patterns.

    PubMed

    Hogenson, George B

    2009-06-01

    The discovery of mirror neurons by researchers at the University of Parma promises to radically alter our understanding of fundamental cognitive and affective states. This paper explores the relationship of mirror neurons to Jung's theory of archetypes and proposes that archetypes may be viewed as elementary action patterns. The paper begins with a review of a proposed interpretation of the fainting spells of S. Freud in his relationship with Jung as an example of an action pattern that also defines an archetypal image. The challenge that mirror neurons present to traditional views in analytical psychology and psychoanalysis, however, is that they operate without recourse to a cognitive processing element. This is a position that is gaining increasing acceptance in other fields as well. The paper therefore reviews the most recent claims made by the Boston Process of Change Study Group as well as conclusions drawn from dynamic systems views of development and theoretical robotics to underline the conclusion that unconscious agency is not a requirement for coherent action. It concludes with the suggestion that this entire body of research may lead to the conclusion that the dynamic unconscious is an unnecessary hypothesis in psychoanalysis and analytical psychology. PMID:19531123

  3. Spin relaxation in geometrically frustrated pyrochlores

    NASA Astrophysics Data System (ADS)

    Dunsiger, Sarah Ruth

    This thesis describes muSR experiments which focus on systems where the magnetic ions occupy the vertices of edge or corner sharing triangular units, in particular the pyrochlores A2B2O7. The scientific interest in pyrochlores is based on the fact that they display novel magnetic behaviour at low temperatures due to geometrical frustration. The ground state of these systems is sensitively dependent on such factors as the range of the spin-spin interactions, disorder, anisotropy, thermal and quantum fluctuations. For example, Y2Mo2O7 shows many features reminiscent of a conventional spin glass, even though this material has nominally zero chemical disorder. It is found that the muon spin polarisation obeys a time-field scaling relation which indicates that the spin-spin autocorrelation function has a power law form in time, in stark contrast with the exponential form often assumed for conventional magnets above their transition temperature. Gd2Ti2O7 shows long range order, but only at a temperature much lower than its Curie-Weiss temperature, a signature of a frustrated system. In the paramagnetic regime, it is well described by an isotropic Heisenberg Hamiltonian with nearest neighbour couplings in the presence of a Zeeman interaction, from which the spin-spin autocorrelation function may be calculated as a power series in time. The muon spin relaxation rate decreases with magnetic field as the Zeeman energy becomes comparable with the exchange coupling between Gd spins. Thus, an independent measure of the exchange coupling or equivalently the Gd spin fluctuation rate is extracted. By contrast, Tb2Ti2O7 has been identified as a type of cooperative paramagnet. Short range correlations develop below 50 K. However, there is no long range ordering down to very low temperatures (0.075 K). The Tb3+ ion is subject to strong crystal electric field effects: point charge calculations indicate that this system is Ising like at low temperatures. Thus this system may be

  4. Titanium pyrochlore magnets: how much can be learned from magnetization measurements?

    NASA Astrophysics Data System (ADS)

    Petrenko, O. A.; Lees, M. R.; Balakrishnan, G.

    2011-04-01

    We report magnetization data for several titanium pyrochlore systems measured down to 0.5 K. The measurements, performed on single crystal samples in fields of up to 7 kOe, have captured the essential elements of the previously reported phase transitions in these compounds and have also revealed additional important features overlooked previously either because of the insufficiently low temperatures used, or due to limitations imposed by polycrystalline samples. For the spin-ice pyrochlores Dy2Ti2O7 and Ho2Ti2O7, an unusually slow relaxation of the magnetization has been observed in lower fields, while the magnetization process in higher fields is essentially hysteresis-free and does not depend on sample history. For the XY pyrochlore Er2Ti2O7, the magnetic susceptibility shows nearly diverging behaviour on approach to a critical field, HC = 13.5 kOe, above which the magnetization does not saturate but continues to grow at a significant rate. For the Heisenberg pyrochlore Gd2Ti2O7, the magnetic susceptibility shows a pronounced change of slope at both transition temperatures, TN1 = 1.02 K and TN2 = 0.74 K, contrary to the earlier reports.

  5. Hydrothermal synthesis of pyrochlores and their characterization

    NASA Astrophysics Data System (ADS)

    Redkin, Alexander F.; Ionov, Andrey M.; Kotova, Nataliya P.

    2013-10-01

    Pyrochlores, microlites, and U-betafites of pyrochlore group minerals were obtained from mixing experiments of the corresponding oxides and fluorides by hydrothermal synthesis at T = 800 °C and P = 200 MPa in the solution of 1.0 M NaF. The presence of U4+ in pyrochlore does not affect the cell parameter, which for the phases of pyrochlore-microlite series is 10.42 ± 0.01 Å. In a system with an excess of UO2, pyrochlores and microlites, containing uranium up to 0.2-0.3 atoms per formula unit (apfu), are formed. In the uranium-free system of betafites composition, perovskites and Ti-bearing pyrochlores are formed. U-pyrochlores of betafite series, containing 2Ti = Nb + Ta in moles, have cubic cell parameters of 10.26 ± 0.02 Å and U4+ isomorphic capacity of 0.4-0.5 apfu. In the pyrochlore structure, U4+ may substitute for Ca2+ and Na+ cations in the eightfold site. In pyrochlores of pyrochlore-microlite series, Ca2+ is replaced by U4+, while in pyrochlores of betafite series, U4+ replaces Na+. Phases with pyrochlore structure, containing U5+ and U6+ in the sixfold site, usually occupied by Nb5+, Ta5+, and Ti4+, are formed under oxidizing conditions (Cu-Cu2O buffer). They are characterized by low content of Nb5+, Ta5+ (<0.1 apfu), and anomalous behavior of the crystal lattice (compression, instead of expansion). Under natural conditions, the formation of pyrochlores containing a significant amount of U5+ and U6+ is unlikely.

  6. Expert witness and Jungian archetypes.

    PubMed

    Lallave, Juan Antonio; Gutheil, Thomas Gordon

    2012-01-01

    Jung's theories of archetype, shadow, and the personal and collective unconscious provide a postmodern framework in which to consider the role of the expert witness in judicial proceedings. Archetypal themes, motifs, and influences help to illuminate the shadow of the judicial system and projections and behaviors among the cast of the court in pursuing justice. This article speaks to archetypal influences and dialectical tensions encountered by the expert witness in this judicial drama. The archetype of Justice is born from the human need for order and relational fairness in a world of chaos. The persona of justice is the promise of truth in the drama. The shadow of justice is untruth, the need to win by any means. The dynamics of the trickster archetype serve and promote injustice. These influences are examined by means of a case example. This approach will deepen understanding of court proceedings and the role of the expert witness in the heroic quest for justice. PMID:23062586

  7. Lead-ruthenium pyrochlores as oxygen electrocatalysts

    NASA Technical Reports Server (NTRS)

    Anderson, E. B.; Taylor, E. J.; Moniz, G. A.

    1990-01-01

    An investigation of lead-ruthenium pyrochlores of the structure Pb2(Ru/2-x/Pb/x/) O7-y for use as oxygen electrocatalysts in alkaline media is discussed. Lead-ruthenium pyrochlore mixed metal oxides were prepared and characterized by X-ray diffraction, BET surface area, dry powder conductivity, and chemical stability. Gas diffusion electrodes were developed specifically for the lead-ruthenium pyrochlore materials. Also investigated were the effects of varying electrode fabrication parameters on the oxygen reduction performance of the lead-ruthenium pyrochlore electrocatalyst. Long-term stability performance was also evaluated. The oxygen reduction performance of the pyrochlore electrocatalyst is considerably higher than that of the state-of-the-art gold-platinum alloy electrocatalyst currently used by NASA. Furthermore, the pyrochlore electrocatalysts are attractive candidates for high-performance pressurized alkaline fuel cells.

  8. Macroscopic anisotropy and symmetry breaking in the pyrochlore antiferromagnet Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Hassan, A. K.; Lévy, L. P.; Darie, C.; Strobel, P.

    2003-06-01

    In the Heisenberg antiferromagnet Gd2Ti2O7, the exchange interactions are geometrically frustrated by the pyrochlore lattice structure. This ESR study reveals a strong temperature dependent anisotropy with respect to a [111] body diagonal below a temperature TA=80 K, despite the spin only nature of the Gd3+ ion. Anisotropy and symmetry breaking can nevertheless appear through the superexchange interaction. In the presence of anisotropic exchanges, short range planar correlations restricted to specific Kagomé planes are sufficient to explain the two ESR modes studied in this work.

  9. Low-frequency spin dynamics of the frustrated pyrochlore magnet Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Smirnov, A. I.; Sosin, S. S.; Glazkov, V. N.; Petrenko, O. A.; Balakrishnan, G.; Zhitomirsky, M. E.

    2009-03-01

    The adiabatic T(H) curves measured in a Heisenberg pyrochlore Gd2Ti2O7 prove the existence of a macroscopic number of local soft modes in this compound. A spin gap of 25 GHz, developing in Gd2Ti2O7 on cooling down to 1.3 K (in the collective paramagneti phase), was observed by ESR spectroscopy. ESR of diamagnetically diluted crystals revealed the single-ion anisotropy energy to be about a quarter of Curie-Weiss temperature. This might be responsible for the observed energy gap. Below 1 K, in the magneticaly ordered phase, the pin excitations have a threebranch spectum with two enegy gaps

  10. Quality requirements for EHR archetypes.

    PubMed

    Kalra, Dipak; Tapuria, Archana; Austin, Tony; De Moor, Georges

    2012-01-01

    The realisation of semantic interoperability, in which any EHR data may be communicated between heterogeneous systems and fully understood by computers as well as people on receipt, is a challenging goal. Despite the use of standardised generic models for the EHR and standard terminology systems, too much optionality and variability exists in how particular clinical entries may be represented. Clinical archetypes provide a means of defining how generic models should be shaped and bound to terminology for specific kinds of clinical data. However, these will only contribute to semantic interoperability if libraries of archetypes can be built up consistently. This requires the establishment of design principles, editorial and governance policies, and further research to develop ways for archetype authors to structure clinical data and to use terminology consistently. Drawing on several years of work within communities of practice developing archetypes and implementing systems from them, this paper presents quality requirements for the development of archetypes. Clinical engagement on a wide scale is also needed to help grow libraries of good quality archetypes that can be certified. Vendor and eHealth programme engagement is needed to validate such archetypes and achieve safe, meaningful exchange of EHR data between systems. PMID:22874150

  11. Quality requirements for EHR archetypes.

    PubMed

    Kalra, Dipak; Tapuria, Archana; Austin, Tony; De Moor, Georges

    2012-01-01

    The realisation of semantic interoperability, in which any EHR data may be communicated between heterogeneous systems and fully understood by computers as well as people on receipt, is a challenging goal. Despite the use of standardised generic models for the EHR and standard terminology systems, too much optionality and variability exists in how particular clinical entries may be represented. Clinical archetypes provide a means of defining how generic models should be shaped and bound to terminology for specific kinds of clinical data. However, these will only contribute to semantic interoperability if libraries of archetypes can be built up consistently. This requires the establishment of design principles, editorial and governance policies, and further research to develop ways for archetype authors to structure clinical data and to use terminology consistently. Drawing on several years of work within communities of practice developing archetypes and implementing systems from them, this paper presents quality requirements for the development of archetypes. Clinical engagement on a wide scale is also needed to help grow libraries of good quality archetypes that can be certified. Vendor and eHealth programme engagement is needed to validate such archetypes and achieve safe, meaningful exchange of EHR data between systems.

  12. Archetypal Analysis for Nominal Observations.

    PubMed

    Seth, Sohan; Eugster, Manuel J A

    2016-05-01

    Archetypal analysis is a popular exploratory tool that explains a set of observations as compositions of few 'pure' patterns. The standard formulation of archetypal analysis addresses this problem for real valued observations by finding the approximate convex hull. Recently, a probabilistic formulation has been suggested which extends this framework to other observation types such as binary and count. In this article we further extend this framework to address the general case of nominal observations which includes, for example, multiple-option questionnaires. We view archetypal analysis in a generative framework: this allows explicit control over choosing a suitable number of archetypes by assigning appropriate prior information, and finding efficient update rules using variational Bayes'. We demonstrate the efficacy of this approach extensively on simulated data, and three real world examples: Austrian guest survey dataset, German credit dataset, and SUN attribute image dataset.

  13. Archetypal Analysis for Nominal Observations.

    PubMed

    Seth, Sohan; Eugster, Manuel J A

    2016-05-01

    Archetypal analysis is a popular exploratory tool that explains a set of observations as compositions of few 'pure' patterns. The standard formulation of archetypal analysis addresses this problem for real valued observations by finding the approximate convex hull. Recently, a probabilistic formulation has been suggested which extends this framework to other observation types such as binary and count. In this article we further extend this framework to address the general case of nominal observations which includes, for example, multiple-option questionnaires. We view archetypal analysis in a generative framework: this allows explicit control over choosing a suitable number of archetypes by assigning appropriate prior information, and finding efficient update rules using variational Bayes'. We demonstrate the efficacy of this approach extensively on simulated data, and three real world examples: Austrian guest survey dataset, German credit dataset, and SUN attribute image dataset. PMID:27046837

  14. [Depression. A symbolic archetypal psychopathology].

    PubMed

    Onofri, Alicia

    2012-01-01

    Jung understood that our psyche had an archetypal structure and that its best representant was mythology. This is a different theoretical framework, with an underlying anthropology that allows us to think pathology under other epistemologic concepts. Pathology can be thought as with positive and negative aspects to consider. This approach lets us consider different types of depression based on an archetypal mythologem, which allows us to think different forms of treatment. PMID:23145375

  15. Heisenberg and the Interpretation of Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Camilleri, Kristian

    2009-02-01

    Preface; 1. Introduction; Part I. The Emergence of Quantum Mechanics: 2. Quantum mechanics and the principle of observability; 3. The problem of interpretation; Part II. The Heisenberg-Bohr Dialogue: 4. The wave-particle duality; 5. Indeterminacy and the limits of classical concepts: the turning point in Heisenberg's thought; 6. Heisenberg and Bohr: divergent viewpoints of complementarity; Part III. Heisenberg's Epistemology and Ontology of Quantum Mechanics: 7. The transformation of Kantian philosophy; 8. The linguistic turn in Heisenberg's thought; Conclusion; References; Index.

  16. Heisenberg and the Interpretation of Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Camilleri, Kristian

    2011-09-01

    Preface; 1. Introduction; Part I. The Emergence of Quantum Mechanics: 2. Quantum mechanics and the principle of observability; 3. The problem of interpretation; Part II. The Heisenberg-Bohr Dialogue: 4. The wave-particle duality; 5. Indeterminacy and the limits of classical concepts: the turning point in Heisenberg's thought; 6. Heisenberg and Bohr: divergent viewpoints of complementarity; Part III. Heisenberg's Epistemology and Ontology of Quantum Mechanics: 7. The transformation of Kantian philosophy; 8. The linguistic turn in Heisenberg's thought; Conclusion; References; Index.

  17. Heisenberg symmetry and hypermultiplet manifolds

    NASA Astrophysics Data System (ADS)

    Antoniadis, Ignatios; Derendinger, Jean-Pierre; Marios Petropoulos, P.; Siampos, Konstantinos

    2016-04-01

    We study the emergence of Heisenberg (Bianchi II) algebra in hyper-Kähler and quaternionic spaces. This is motivated by the rôle these spaces with this symmetry play in N = 2 hypermultiplet scalar manifolds. We show how to construct related pairs of hyper-Kähler and quaternionic spaces under general symmetry assumptions, the former being a zooming-in limit of the latter at vanishing scalar curvature. We further apply this method for the two hyper-Kähler spaces with Heisenberg algebra, which is reduced to U (1) × U (1) at the quaternionic level. We also show that no quaternionic spaces exist with a strict Heisenberg symmetry - as opposed to Heisenberg ⋉ U (1). We finally discuss the realization of the latter by gauging appropriate Sp (2 , 4) generators in N = 2 conformal supergravity.

  18. Pyrochlore catalysts for hydrocarbon fuel reforming

    DOEpatents

    Berry, David A.; Shekhawat, Dushyant; Haynes, Daniel; Smith, Mark; Spivey, James J.

    2012-08-14

    A method of catalytically reforming a reactant gas mixture using a pyrochlore catalyst material comprised of one or more pyrochlores having the composition A2B2-y-zB'yB"zO7-.DELTA., where y>0 and z.gtoreq.0. Distribution of catalytically active metals throughout the structure at the B site creates an active and well dispersed metal locked into place in the crystal structure. This greatly reduces the metal sintering that typically occurs on supported catalysts used in reforming reactions, and reduces deactivation by sulfur and carbon. Further, oxygen mobility may also be enhanced by elemental exchange of promoters at sites in the pyrochlore. The pyrochlore catalyst material may be utilized in catalytic reforming reactions for the conversion of hydrocarbon fuels into synthesis gas (H2+CO) for fuel cells, among other uses.

  19. Archetypes of Outstanding Female Superintendents.

    ERIC Educational Resources Information Center

    Funk, Carole; Pankake, Anita; Schroth, Gwen

    This report documents a study of women superintendents. Specifically, the study identified professional and personal characteristics and styles of leadership to develop archetypes of six outstanding female superintendents in Texas. The intent of the research was also to reveal similarities between and among these superintendents that could provide…

  20. Recent neutron scattering results from Gd-based pyrochlore oxides

    NASA Astrophysics Data System (ADS)

    Gardner, Jason

    2009-03-01

    In my presentation I will present recent results that have determined the spin-spin correlations in the geometrically frustrated magnets Gd2Sn2O7 and Gd2Ti2O7. This will include polarised neutron diffraction, inelastic neutron scattering and neutron spin echo data. One sample of particular interest is Gd2Sn2O7 which is believed to be a good approximation to a Heisenberg antiferromagnet on a pyrochlore lattice with exchange and dipole-dipole interactions. Theoretically such a system is expected to enter long range ordered ground state known as the ``Palmer Chalker'' state [1]. We show conclusively, through neutron scattering data, that the system indeed enters an ordered state with the Palmer-Chalker spin configuration below Tc = 1 K [2-3]. Within this state we have also observed long range collective spin dynamics, spin waves. This work has been performed in collaboration with many research groups including G. Ehlers (SNS), R. Stewart (ISIS). [0pt] [1] S. E. Palmer and J. T. Chalker, Phys. Rev. B 62, 488 (2000). [0pt] [2] J. R. Stewart, G. Ehlers, A. S. Wills, S. T. Bramwell, and J. S. Gardner, J. Phys.: Condens. Matter 16, L321 (2004). [0pt] [3] J R Stewart, J S Gardner, Y. Qiu and G Ehlers, Phys. Rev. B. 78, 132410 (2008)

  1. Towards Archetypes-Based Software Development

    NASA Astrophysics Data System (ADS)

    Piho, Gunnar; Roost, Mart; Perkins, David; Tepandi, Jaak

    We present a framework for the archetypes based engineering of domains, requirements and software (Archetypes-Based Software Development, ABD). An archetype is defined as a primordial object that occurs consistently and universally in business domains and in business software systems. An archetype pattern is a collaboration of archetypes. Archetypes and archetype patterns are used to capture conceptual information into domain specific models that are utilized by ABD. The focus of ABD is on software factories - family-based development artefacts (domain specific languages, patterns, frameworks, tools, micro processes, and others) that can be used to build the family members. We demonstrate the usage of ABD for developing laboratory information management system (LIMS) software for the Clinical and Biomedical Proteomics Group, at the Leeds Institute of Molecular Medicine, University of Leeds.

  2. Sub-Heisenberg phase uncertainties

    NASA Astrophysics Data System (ADS)

    Pezzé, Luca

    2013-12-01

    Phase shift estimation with uncertainty below the Heisenberg limit, ΔϕHL∝1/N¯T, where N¯T is the total average number of particles employed, is a mirage of linear quantum interferometry. Recently, Rivas and Luis, [New J. Phys.NJOPFM1367-263010.1088/1367-2630/14/9/093052 14, 093052 (2012)] proposed a scheme to achieve a phase uncertainty Δϕ∝1/N¯Tk, with k an arbitrary exponent. This sparked an intense debate in the literature which, ultimately, does not exclude the possibility to overcome ΔϕHL at specific phase values. Our numerical analysis of the Rivas and Luis proposal shows that sub-Heisenberg uncertainties are obtained only when the estimator is strongly biased. No violation of the Heisenberg limit is found after bias correction or when using a bias-free Bayesian analysis.

  3. Berry phase in Heisenberg representation

    NASA Technical Reports Server (NTRS)

    Andreev, V. A.; Klimov, Andrei B.; Lerner, Peter B.

    1994-01-01

    We define the Berry phase for the Heisenberg operators. This definition is motivated by the calculation of the phase shifts by different techniques. These techniques are: the solution of the Heisenberg equations of motion, the solution of the Schrodinger equation in coherent-state representation, and the direct computation of the evolution operator. Our definition of the Berry phase in the Heisenberg representation is consistent with the underlying supersymmetry of the model in the following sense. The structural blocks of the Hamiltonians of supersymmetrical quantum mechanics ('superpairs') are connected by transformations which conserve the similarity in structure of the energy levels of superpairs. These transformations include transformation of phase of the creation-annihilation operators, which are generated by adiabatic cyclic evolution of the parameters of the system.

  4. Microstructure and Composition of a Ce-pyrochlore: A Chemical Analog for Pu-pyrochlore

    NASA Astrophysics Data System (ADS)

    Xu, Huifang; Wang, Yifeng; Garvie, Laurence A. J.; Putnam, Robert L.; Navrotsky, Alexandra

    2003-07-01

    Ce-pyrochlore (CaCeTi2O7), is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapon-usable Pu in geological repositories. Ce-pyrochlore was synthesized by firing and annealing a mixture of Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1,300°C for 50 hours. The annealed product contains Ce-pyrochlore, Ce-bearing perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) was used to determine the valence of Ce in the synthesized materials using the shape of the Ce M4,5 edge. Cerium in the perovskite is dominated by Ce3+. The Ce4+/ΣCe in the pyrochlore is 0.8, giving (Ca0.87Ce0.203+Ce0.864+Ti0.05)Ti2O7. High-resolution TEM images show that the boundary between pyrochlore and perovskite is semicoherently bonded. The orientational relationship between the neighboring pyrochlore and perovskite is not random. There are no glassy phases observed at the grain boundaries between pyrochlore and perovskite, and between CeO2 and pyrochlore. It is postulated, based on the presence of trivalent Ce in the Ce-pyrochlore, that the neutron poisons such as Gd can be incorporated into the CaPuTi2O7 phase.

  5. Using archetypes for defining CDA templates.

    PubMed

    Moner, David; Moreno, Alberto; Maldonado, José A; Robles, Montserrat; Parra, Carlos

    2012-01-01

    While HL7 CDA is a widely adopted standard for the documentation of clinical information, the archetype approach proposed by CEN/ISO 13606 and openEHR is gaining recognition as a means of describing domain models and medical knowledge. This paper describes our efforts in combining both standards. Using archetypes as an alternative for defining CDA templates permit new possibilities all based on the formal nature of archetypes and their ability to merge into the same artifact medical knowledge and technical requirements for semantic interoperability of electronic health records. We describe the process followed for the normalization of existing legacy data in a hospital environment, from the importation of the HL7 CDA model into an archetype editor, the definition of CDA archetypes and the application of those archetypes to obtain normalized CDA data instances. PMID:22874151

  6. Magnetic phase diagram of the antiferromagnetic pyrochlore Gd2 Ti2 O7

    NASA Astrophysics Data System (ADS)

    Petrenko, O. A.; Lees, M. R.; Balakrishnan, G.; Paul, D. Mck

    2004-07-01

    Gd2Ti2O7 is a highly frustrated antiferromagnet on a pyrochlore lattice, where apart from the Heisenberg exchange the spins also interact via dipole-dipole forces. We report on low-temperature specific heat measurements performed on single crystals of Gd2Ti2O7 for three different directions of an applied magnetic field. The measurements reveal the strongly anisotropic behavior of Gd2Ti2O7 in a magnetic field despite the apparent absence of a significant single-ion anisotropy for Gd3+ . The H-T phase diagrams are constructed for H∥[111] , H∥[110] , and H∥[112] . The results indicate that further theoretical work beyond a simple mean-field model is required.

  7. Heisenberg and the critical mass

    NASA Astrophysics Data System (ADS)

    Bernstein, Jeremy

    2002-09-01

    An elementary treatment of the critical mass used in nuclear weapons is presented and applied to an analysis of the wartime activities of the German nuclear program. In particular, the work of Werner Heisenberg based on both wartime and postwar documents is discussed.

  8. Archetypes and patriarchy: Eliade and Jung.

    PubMed

    Meadow, M J

    1992-09-01

    This paper first presents the understandings of the concept of archetype held by Carl Jung and Mircea Eliade. After comparing their use of the term, the paper next presents some major archetypes concerning sex roles that each theorist describes. The problems such notions create for women are analyzed. The paper ends with a discussion of some possible solutions to the difficulties caused by the human proclivity for archetypal imaging.

  9. Archetypes and patriarchy: Eliade and Jung.

    PubMed

    Meadow, M J

    1992-09-01

    This paper first presents the understandings of the concept of archetype held by Carl Jung and Mircea Eliade. After comparing their use of the term, the paper next presents some major archetypes concerning sex roles that each theorist describes. The problems such notions create for women are analyzed. The paper ends with a discussion of some possible solutions to the difficulties caused by the human proclivity for archetypal imaging. PMID:24271049

  10. National governance of archetypes in Norway.

    PubMed

    Ljosland Bakke, Silje

    2015-01-01

    Norwegian National ICT has implemented a national governance scheme for archetypes. The scheme uses openEHR, and is possibly the first of its kind worldwide. It introduces several new processes and methods for crowd sourcing clinician input. It has spent much of its first year establishing practical processes and recruiting clinicians, and only a few archetypes has been reviewed and approved. Some non-reusable archetypes have emerged while the governance scheme has established itself, which demonstrates the need for a centralised governance. As the mass of clinician involvement reached a critical point at the end of 2014, the rate of archetype review and approval increased. PMID:26262390

  11. Archetypes of famine and response.

    PubMed

    Howe, Paul

    2010-01-01

    Famines have long been characterised by rapidly shifting dynamics: sudden price spirals, sharp increases in mortality, the media frenzy that often accompanies such spikes, the swift scaling up of aid flows, and a subsequent decline in interest. In arguing that these aspects of famine have been largely ignored in recent years due to attention to the famine process', this paper attempts to make these dynamics more explicit by applying systems thinking. It uses standard archetypes of systems thinking to explain six situations--watch, price spiral, aid magnet, media frenzy, overshoot, and peaks--that are present in many famine contexts. It illustrates their application with examples from crises in Ethiopia, Malawi, Niger, and Sudan. The paper contends that the systems approach offers a tool for analysing the larger patterns in famines and for pinpointing the most appropriate responses to them, based on an awareness of the dynamics of the crises.

  12. An archetype hydrogen atmosphere problem

    NASA Technical Reports Server (NTRS)

    Athay, R. G.; Mihalas, D.; Shine, R. A.

    1975-01-01

    Populations for the first three bound states and the continuum of hydrogen are determined for an isothermal hydrostatic atmosphere at 20,000 K. The atmosphere is treated as optically thin in the Balmer and Paschen continua and illuminated by continuum radiation at these wavelengths with prescribed radiation temperatures. The atmosphere is optically thick in the 2-1, 3-1, 3-2 and c-1 transitions. Three stages of approximation are treated: (1) radiative detailed balance in the 2-1, 3-1 and 3-2 transitions, (2) radiative detailed balance in the 3-1 and 3-2 transitions, and (3) all transitions out of detailed balance. The solution of this problem is nontrivial and presents sufficient difficulty to have caused the failure of at least one rather standard technique. The problem is thus a good archetype against which new methods or new implementations of old methods may be tested.

  13. Weyl magnons in breathing pyrochlore antiferromagnets.

    PubMed

    Li, Fei-Ye; Li, Yao-Dong; Kim, Yong Baek; Balents, Leon; Yu, Yue; Chen, Gang

    2016-01-01

    Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems. PMID:27650053

  14. Calcium uranium titanate—A new pyrochlore

    NASA Astrophysics Data System (ADS)

    Dickson, F. J.; Hawkins, K. D.; White, T. J.

    1989-09-01

    Calcium uranium dititanate pyrochlore ( A2B2O 7), a component of a high-level nuclear waste ceramic, was characterized by powder X-ray diffraction, analytical electron microscopy and selected area electron diffraction. The cubic unit cell ( a = 10.1579(5) Å) has symmetry Fd overline3m with A in 16( c), B in 16( d), O 1 in 48( f), and O 2 in 8( a). A preliminary examination of the peak intensity in X-ray powder patterns and chemical analyses by energy dispersive X-ray spectroscopy suggest that although this pyrochlore can be approximately described by the crystallochemical formula [Ca, U][Ti 2]O 7 the {Ca}/{U} ratio may deviate from unity with some trivalent titanium partitioning onto the A-site.

  15. Weyl magnons in breathing pyrochlore antiferromagnets

    NASA Astrophysics Data System (ADS)

    Li, Fei-Ye; Li, Yao-Dong; Kim, Yong Baek; Balents, Leon; Yu, Yue; Chen, Gang

    2016-09-01

    Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems.

  16. Weyl magnons in breathing pyrochlore antiferromagnets

    PubMed Central

    Li, Fei-Ye; Li, Yao-Dong; Kim, Yong Baek; Balents, Leon; Yu, Yue; Chen, Gang

    2016-01-01

    Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems. PMID:27650053

  17. Theory of disordered Heisenberg ferromagnets

    NASA Technical Reports Server (NTRS)

    Stubbs, R. M.

    1973-01-01

    A Green's function technique is used to calculate the magnetic properties of Heisenberg ferromagnets in which the exchange interactions deviate randomly in strength from the mean interaction. Systems of sc, bcc, and fcc topologies and of general spin values are treated. Disorder produces marked effects in the density of spin wave states, in the form of enhancement of the low-energy density and extension of the energy band to higher values. The spontaneous magnetization and the Curie temperature decrease with increasing disorder. The effects of disorder are shown to be more pronounced in the ferromagnetic than in the paramagnetic phase.

  18. Tunable Magnon Weyl Points in Ferromagnetic Pyrochlores

    NASA Astrophysics Data System (ADS)

    Mook, Alexander; Henk, Jürgen; Mertig, Ingrid

    2016-10-01

    The dispersion relations of magnons in ferromagnetic pyrochlores with Dzyaloshinskii-Moriya interaction are shown to possess Weyl points, i. e., pairs of topologically nontrivial crossings of two magnon branches with opposite topological charge. As a consequence of their topological nature, their projections onto a surface are connected by magnon arcs, thereby resembling closely Fermi arcs of electronic Weyl semimetals. On top of this, the positions of the Weyl points in reciprocal space can be tuned widely by an external magnetic field: rotated within the surface plane, the Weyl points and magnon arcs are rotated as well; tilting the magnetic field out of plane shifts the Weyl points toward the center Γ ¯ of the surface Brillouin zone. The theory is valid for the class of ferromagnetic pyrochlores, i. e., three-dimensional extensions of topological magnon insulators on kagome lattices. In this Letter, we focus on the (111) surface, identify candidates of established ferromagnetic pyrochlores which apply to the considered spin model, and suggest experiments for the detection of the topological features.

  19. Mn4+ emission in pyrochlore oxides

    DOE PAGESBeta

    Du, Mao-Hua

    2015-01-01

    For the existing Mn4+ activated red phosphors have relatively low emission energies (or long emission wavelengths) and are therefore inefficient for general lighting. Density functional calculations are performed to study Mn4+ emission in rare-earth hafnate, zirconate, and stannate pyrochlore oxides (RE2Hf2O7, RE2Zr2O7, and RE2Sn2O7). We show how the different sizes of the RE3+ cation in these pyrochlores affect the local structure of the distorted MnO6 octahedron, the Mn–O hybridization, and the Mn4+ emission energy. The Mn4+ emission energies of many pyrochlores are found to be higher than those currently known for Mn4+ doped oxides and should be closer to thatmore » of Y2O3:Eu3+ (the current commercial red phosphor for fluorescent lighting). The O–Mn–O bond angle distortion in a MnO6 octahedron is shown to play an important role in weakening Mn–O hybridization and consequently increasing the Mn4+ emission energy. Our result shows that searching for materials that allow significant O–Mn–O bond angle distortion in a MnO6 octahedron is an effective approach to find new Mn4+ activated red phosphors with potential to replace the relatively expensive Y2O3:Eu3+ phosphor.« less

  20. Conjugacy classes in discrete Heisenberg groups

    SciTech Connect

    Budylin, R Ya

    2014-08-01

    We study an extension of a discrete Heisenberg group coming from the theory of loop groups and find invariants of conjugacy classes in this group. In some cases, including the case of the integer Heisenberg group, we make these invariants more explicit. Bibliography: 4 titles.

  1. An archetype-based testing framework.

    PubMed

    Chen, Rong; Garde, Sebastian; Beale, Thomas; Nyström, Mikael; Karlsson, Daniel; Klein, Gunnar O; Ahlfeldt, Hans

    2008-01-01

    With the introduction of EHR two-level modelling and archetype methodologies pioneered by openEHR and standardized by CEN/ISO, we are one step closer to semantic interoperability and future-proof adaptive healthcare information systems. Along with the opportunities, there are also challenges. Archetypes provide the full semantics of EHR data explicitly to surrounding systems in a platform-independent way, yet it is up to the receiving system to interpret the semantics and process the data accordingly. In this paper we propose a design of an archetype-based platform-independent testing framework for validating implementations of the openEHR archetype formalism as a means of improving quality and interoperability of EHRs.

  2. Archetypes, complexes and self-organization.

    PubMed

    Saunders, P; Skar, P

    2001-04-01

    There has always been confusion and disagreement about the nature of the terms archetype and complex in Jungian circles, not to mention non-Jungian ones. Another ongoing concern is whether Jung's concept of the archetype and complex can be justified in terms of current scientific research, most notably that of neurophysiologists and others interested in the brain and consciousness. This paper proposes a theory of the formation of complexes, namely, that they are created through self-organization within the brain/mind. Self-organization is a process typical of large complex systems, and is generally accepted to operate within the brain and to be important in its functioning. Examples of self-organization in biology are related to the psychic processes that form the complexes. It is then natural to define the archetype in terms of the complex, and the authors propose a definition of the archetype as an equivalence class of complexes. On this view, the archetype is an emergent property of the activity of the brain/mind, and is, appropriately, defined at the level at which it emerges. This definition is in line with the original development of Jung's ideas, in that he derived the concept of the archetype from his earlier discovery of the feeling-toned complex. PMID:11307698

  3. Archetypes and Assignments: Writing about Personal Archetypes Aids Students in Writing Composition Papers and Understanding Literature.

    ERIC Educational Resources Information Center

    Crow, Edith

    Combining the study of archetypal patterns and literature study with assignments based on archetypal schema engages students intellectually as they relate their personal experiences to texts outside of themselves. This approach is grounded in the theory that engagement in a topic, whether reading or writing, is essential for the learner to make…

  4. Did Heisenberg Spit at Max Born?

    NASA Astrophysics Data System (ADS)

    Lustig, Harry

    2005-04-01

    In his 1985 book ``The Griffin,'' Arnold Kramish quotes an unnamed ``associate'' of Max Born that when Heisenberg ''was . . . a professor in Göttingen and when the Borns went to visit him, they were met with anti-Jewish sneers and obscenities, and in the end Heisenberg spat on the floor at Max Born's feet!". Kramish, in his own words, states that Heisenberg spat at Born and that the incident took place in 1933. Paul Lawrence Rose places the incident in 1953 and, on the basis of a fuller account from Kramish than the one published, identifies the associate as Born's secretary at Edinburgh University. One may be critical of Heisenberg's character and his behavior under the Nazis, and still be highly skeptical of the Kramish-Rose allegation. The life-long friendship between Born and Heisenberg and the respect which they displayed for each other before, during, and after the Nazi regime, has hardly been challenged by anyone. No known biography of Heisenberg mentions the alleged episode, and none of his obituaries alludes to it. There is no reference to it in Born's autobiography. None of the historians of science, German and American, whom I have consulted credit it. Although it is difficult to prove a negative, it is highly unlikely that Heisenberg spit at Born or on the floor on which they stood.

  5. Anisotropic Exchange within Decoupled Tetrahedra in the Quantum Breathing Pyrochlore Ba_{3}Yb_{2}Zn_{5}O_{11}.

    PubMed

    Rau, J G; Wu, L S; May, A F; Poudel, L; Winn, B; Garlea, V O; Huq, A; Whitfield, P; Taylor, A E; Lumsden, M D; Gingras, M J P; Christianson, A D

    2016-06-24

    The low energy spin excitation spectrum of the breathing pyrochlore Ba_{3}Yb_{2}Zn_{5}O_{11} has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. To gain deeper insight, a theoretical model of isolated Yb^{3+} tetrahedra parametrized by four anisotropic exchange constants is constructed. The model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. The fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of intertetrahedron correlations. PMID:27391749

  6. Anisotropic Exchange within Decoupled Tetrahedra in the Quantum Breathing Pyrochlore Ba3Yb2Zn5O11

    NASA Astrophysics Data System (ADS)

    Rau, J. G.; Wu, L. S.; May, A. F.; Poudel, L.; Winn, B.; Garlea, V. O.; Huq, A.; Whitfield, P.; Taylor, A. E.; Lumsden, M. D.; Gingras, M. J. P.; Christianson, A. D.

    2016-06-01

    The low energy spin excitation spectrum of the breathing pyrochlore Ba3Yb2Zn5O11 has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. To gain deeper insight, a theoretical model of isolated Yb3 + tetrahedra parametrized by four anisotropic exchange constants is constructed. The model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. The fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of intertetrahedron correlations.

  7. Anisotropic Exchange within Decoupled Tetrahedra in the Quantum Breathing Pyrochlore Ba3Yb2Zn5O11

    DOE PAGESBeta

    Rau, J. G.; Wu, L. S.; May, A. F.; Poudel, L.; Winn, B.; Garlea, V. O.; Huq, A.; Whitfield, P.; Taylor, A. E.; Lumsden, M. D.; et al

    2016-06-24

    Tmore » he low energy spin excitation spectrum of the breathing pyrochlore Ba3Yb2Zn5O11 has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. o gain deeper insight, a theoretical model of isolated Yb3+ tetrahedra parametrized by four anisotropic exchange constants is constructed. he model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. he fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Ultimately, using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of inter-tetrahedron correlations.« less

  8. Werner Heisenberg (1901-1976)

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Werner Heisenberg was one of the greatest physicists of all times. When he started out as a young research worker, the world of physics was in a very confused and frustrating state, which Abraham Pais has described1 as: It was the spring of hope, it was the winter of despair using Charles Dickens' words in A Tale of Two Cities. People were playing a guessing game: There were from time to time great triumphs in proposing, through sheer intuition, make-shift schemes that amazingly explained some regularities in spectral physics, leading to joy. But invariably such successes would be followed by further work which reveal the inconsistency or inadequacy of the new scheme, leading to despair...

  9. Quantum states for Heisenberg-limited interferometry

    SciTech Connect

    Uys, H.; Meystre, P.

    2007-07-15

    The phase sensitivity of interferometers is limited by the so-called Heisenberg limit, which states that the optimum phase sensitivity is inversely proportional to the number of interfering particles N, a 1/{radical}(N) improvement over the standard quantum limit. We have used simulated annealing, a global optimization strategy, to systematically search for quantum interferometer input states that approach the Heisenberg-limited uncertainty in estimates of the interferometer phase shift. We compare the performance of these states to that of other nonclassical states already known to yield Heisenberg-limited uncertainty.

  10. 100 Years Werner Heisenberg: Works and Impact

    NASA Astrophysics Data System (ADS)

    Papenfuß, Dietrich; Lüst, Dieter; Schleich, Wolfgang P.

    2003-09-01

    Over 40 renowned scientists from all around the world discuss the work and influence of Werner Heisenberg. The papers result from the symposium held by the Alexander von Humboldt-Stiftung on the occasion of the 100th anniversary of Heisenberg's birth, one of the most important physicists of the 20th century and cofounder of modern-day quantum mechanics. Taking atomic and laser physics as their starting point, the scientists illustrate the impact of Heisenberg's theories on astroparticle physics, high-energy physics and string theory right up to processing quantum information.

  11. [The evolution of the concept of archetypes in Jungian psychology].

    PubMed

    Pérez Urdaniz, A; Romero, E F

    1995-01-01

    The concept of archetype is basic in the Junguian conception of the human mind. Without archetypes the Junguian theory of the collective unconscions is absurd. Jung himself recognized that the concept of archetype had originated the worst misunderstandings of his theories. Within Junguian schools there is an archetypal school which has originated archetypal conceptions quite apart from the initial junguian ideas. In this paper the evolution of the concept of archetype is studied, and its implications for the practice of Junguian psychotherapy are considered.

  12. [The evolution of the concept of archetypes in Jungian psychology].

    PubMed

    Pérez Urdaniz, A; Romero, E F

    1995-01-01

    The concept of archetype is basic in the Junguian conception of the human mind. Without archetypes the Junguian theory of the collective unconscions is absurd. Jung himself recognized that the concept of archetype had originated the worst misunderstandings of his theories. Within Junguian schools there is an archetypal school which has originated archetypal conceptions quite apart from the initial junguian ideas. In this paper the evolution of the concept of archetype is studied, and its implications for the practice of Junguian psychotherapy are considered. PMID:8553923

  13. Brow archetype preferred by Korean women.

    PubMed

    Kim, Seong Kee; Cha, Seung Hyun; Hwang, Kun; Hwang, Se Won; Kim, Young Suk

    2014-07-01

    The aim of this study is to see which brow archetype is preferred by Korean women. The archetypes were chosen from a literature search, which contain detailed, replicable methods and have diagrams (Westmore, Lamas, Anastasia, Schreiber, and Hwang). A survey was conducted on 300 subjects (group A, 100 female medical students; group B, 100 women who had visited a plastic surgery clinic for periorbital rejuvenation; and group C, 100 women who visited the brow bar). They were asked whether they think there might be a method that yields an ideal brow archetype. In the cases where they said yes, they were asked to choose 1 of the illustrated 5 brow archetypes that they think is ideal. Among the 300 respondents, 232 (77.3%) thought there might be a method to yield an ideal brow archetype, whereas 68 (22.7%) answered they did not. The preference for the brow archetypes was different among the 5 archetypes (P = 0.0001, χ2). Anastasia was the most preferred (44.8%, brow starts on a perpendicular line drawn from the middle of the nostril, arches on a line drawn from the center of the nose through the center of the pupil, and ends on a line drawn from the edge of the corresponding nasal ala through the outer edge of the eye). Anastasia was followed by Lamas (22.0%). In group A, Anastasia (55.7%) was the most preferred, followed by Lamas (26.2%) and Westmore (13.1%). In group B, Anastasia (34.8%) was the most preferred, followed by Lamas (30.3%) and Westmore and Schreiber (both 13.5%). In group C, Anastasia (47.6%) was the most preferred, followed by Hwang (25.5%) and Westmore (11.0%). There was a significant difference (P < 0.001) among the 3 groups. There was a significant correlation between the preference of brow archetype and occupation (P = 0.0033). However, no significant differences were noted for the preference of brow archetype between the age groups of younger than 30 years and older than 30 years (P = 0.1374), level of education (P = 0.3403), marital status (P = 0

  14. Brow archetype preferred by Korean women.

    PubMed

    Kim, Seong Kee; Cha, Seung Hyun; Hwang, Kun; Hwang, Se Won; Kim, Young Suk

    2014-07-01

    The aim of this study is to see which brow archetype is preferred by Korean women. The archetypes were chosen from a literature search, which contain detailed, replicable methods and have diagrams (Westmore, Lamas, Anastasia, Schreiber, and Hwang). A survey was conducted on 300 subjects (group A, 100 female medical students; group B, 100 women who had visited a plastic surgery clinic for periorbital rejuvenation; and group C, 100 women who visited the brow bar). They were asked whether they think there might be a method that yields an ideal brow archetype. In the cases where they said yes, they were asked to choose 1 of the illustrated 5 brow archetypes that they think is ideal. Among the 300 respondents, 232 (77.3%) thought there might be a method to yield an ideal brow archetype, whereas 68 (22.7%) answered they did not. The preference for the brow archetypes was different among the 5 archetypes (P = 0.0001, χ2). Anastasia was the most preferred (44.8%, brow starts on a perpendicular line drawn from the middle of the nostril, arches on a line drawn from the center of the nose through the center of the pupil, and ends on a line drawn from the edge of the corresponding nasal ala through the outer edge of the eye). Anastasia was followed by Lamas (22.0%). In group A, Anastasia (55.7%) was the most preferred, followed by Lamas (26.2%) and Westmore (13.1%). In group B, Anastasia (34.8%) was the most preferred, followed by Lamas (30.3%) and Westmore and Schreiber (both 13.5%). In group C, Anastasia (47.6%) was the most preferred, followed by Hwang (25.5%) and Westmore (11.0%). There was a significant difference (P < 0.001) among the 3 groups. There was a significant correlation between the preference of brow archetype and occupation (P = 0.0033). However, no significant differences were noted for the preference of brow archetype between the age groups of younger than 30 years and older than 30 years (P = 0.1374), level of education (P = 0.3403), marital status (P = 0

  15. Adiabatic limits on Riemannian Heisenberg manifolds

    SciTech Connect

    Yakovlev, A A

    2008-02-28

    An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.

  16. The many faces of order-by-disorder in rare-earth pyrochlore magnets

    NASA Astrophysics Data System (ADS)

    Gingras, Michel J. P.

    Order-by-disorder (ObD) is a concept of central importance in the field of frustrated magnetism. Saddled with large accidental degeneracies, a subset of states, those that support the largest quantum and/or thermal fluctuations, may be selected to form true long-range order. More formally, one often begins describing a system in terms of some order parameter m with the low-energy description framed in terms of an effective action Γ (m) . In each ObD scenario, one starts from an artificial limit where there is an accidental degeneracy; that is the effective action at this point, Γ0 (m) , has an accidental symmetry. One may then view ObD phenomena as cases where the corrections to Γ0 (m) arise through some form of fluctuation corrections, may they be thermal, quantum or virtual, towards an enlarged higher energy Hilbert space. In the rare-earth pyrochlore oxides, of formula R2M2O7, the trivalent magnetic rare-earth ions R3+ (e.g R = Gd, Er, Yb; M = Ti, Sn is non-magnetic) reside on a three-dimensional pyrochlore lattice of corner-sharing tetrahedra. This architecture is prone to a high degree of magnetic frustration, with the R2M2 O7 pyrochlore materials having been found over the past twenty years to display a gamut of exotic phenomena. In this talk, I will discuss three such phenomena: (i) the intermediate partially-ordered multiple- k state between 0 . 7 K and 1K in the Gd2Ti2O7 Heisenberg antiferromagnet, (ii) the ordered ψ2 state selection in the XY Er2Ti2O7 antiferromagnet and (iii) the puzzling high sample sensitivity of the Yb2Ti2O7 ``quantum spin ice'' candidate. I will argue that in all three cases, some form of fluctuation corrections to their simplest Γ0 (m) description play a significant role in the state selection and experimentally observed behaviors.

  17. Numerical Archetypal Parameterization for Mesoscale Convective Systems

    NASA Astrophysics Data System (ADS)

    Yano, J. I.

    2015-12-01

    Vertical shear tends to organize atmospheric moist convection into multiscale coherent structures. Especially, the counter-gradient vertical transport of horizontal momentum by organized convection can enhance the wind shear and transport kinetic energy upscale. However, this process is not represented by traditional parameterizations. The present paper sets the archetypal dynamical models, originally formulated by the second author, into a parameterization context by utilizing a nonhydrostatic anelastic model with segmentally-constant approximation (NAM-SCA). Using a two-dimensional framework as a starting point, NAM-SCA spontaneously generates propagating tropical squall-lines in a sheared environment. A high numerical efficiency is achieved through a novel compression methodology. The numerically-generated archetypes produce vertical profiles of convective momentum transport that are consistent with the analytic archetype.

  18. Three-dimensional topological insulators on the pyrochlore lattice.

    PubMed

    Guo, H-M; Franz, M

    2009-11-13

    Electrons hopping on the sites of a three-dimensional pyrochlore lattice are shown to form topologically nontrivial insulating phases when the spin-orbit (SO) coupling and lattice distortions are present. Of 16 possible topological classes 9 are realized for various parameters in this model. Specifically, at half-filling an undistorted pyrochlore lattice with a SO term yields a "pristine" strong topological insulator with a Z(2) index (1;000). At quarter filling various strong and weak topological phases are obtained provided that both SO coupling and uniaxial lattice distortion are present. Our analysis suggests that many of the nonmagnetic insulating pyrochlores could be topological insulators.

  19. Neutron Scattering from Magnetically Frustrated Ruthenium Pyrochlores

    NASA Astrophysics Data System (ADS)

    Broholm, Collin

    2008-03-01

    Spin-1 ruthenium pyrochlores feature strong exchange interactions and deeply suppressed N'eel ordering. In addition a doping induced metallic phase has been demonstrated. I discuss neutron scattering experiments that explore the strongly frustrated quantum magnetism of Y2Ru2O7 [1] and Pr2-xBixRu2O7 [2]. In Y2Ru2O7 (θCW= --1100 K, TN=77 K) much of the magnetic spectral weight is concentrated in a 20 meV spectral peak above an 11 meV low temperature gap in the excitation spectrum. In Pr2-xBixRu2O7 magnetic order which occurs for Tpyrochlores. [1] J. van Duijn, N. Hur, J. W. Taylor, Y. Qiu, Q. Z. Huang, S.-W. Cheong, C. Broholm, and T. G. Perring, Submitted to Phys. Rev. B Rapid Communications, cond-mat 0707.2678v1 (2007). [2] J. van Duijn, K. H. Kim, N. Hur, D. Adroja, M. A. Adams, Q. Z. Huang, M. Jaime, S.-W. Cheong, C. Broholm, and T. G. Perring, Phys. Rev. Lett. 94, 177201 (2005).

  20. Effect of swift heavy ion irradiation in pyrochlores

    NASA Astrophysics Data System (ADS)

    Patel, M. K.; Vijayakumar, V.; Avasthi, D. K.; Kailas, S.; Pivin, J. C.; Grover, V.; Mandal, B. P.; Tyagi, A. K.

    2008-06-01

    A summary of the results on the radiation stability of pyrochlores (Gd2Zr2O7, Nd2Zr2O7, Gd2Ti2O7) in the electronic stopping regime is given. X-ray diffraction and Raman spectroscopy show a transformation from the ordered pyrochlores (Fd3m) to the anion deficient fluorite (Fm3m) structure in Gd2Zr2O7 or amorphization in Nd2Zr2O7. The track diameter, crystallite size and progression in structural modifications have been monitored. It is found that radiation stability of these pyrochlores depends on the energy to form cation antisites and delocalized anion vacancies. This in turn is correlated to the radius ratio of A-B cations. This criterion for evaluating radiation resistance of pyrochlores has important implications in the field of inert matrix fuels.

  1. Pyrochlore-type catalysts for the reforming of hydrocarbon fuels

    DOEpatents

    Berry, David A.; Shekhawat, Dushyant; Haynes, Daniel; Smith, Mark; Spivey, James J.

    2012-03-13

    A method of catalytically reforming a reactant gas mixture using a pyrochlore catalyst material comprised of one or more pyrochlores having the composition A.sub.2-w-xA'.sub.wA''.sub.xB.sub.2-y-zB'.sub.yB''.sub.zO.sub.7-.DELTA.. Distribution of catalytically active metals throughout the structure at the B site creates an active and well dispersed metal locked into place in the crystal structure. This greatly reduces the metal sintering that typically occurs on supported catalysts used in reforming reactions, and reduces deactivation by sulfur and carbon. Further, oxygen mobility may also be enhanced by elemental exchange of promoters at sites in the pyrochlore. The pyrochlore catalyst material may be utilized in catalytic reforming reactions for the conversion of hydrocarbon fuels into synthesis gas (H.sub.2+CO) for fuel cells, among other uses.

  2. The Teacher as an Archetype of Spirit

    ERIC Educational Resources Information Center

    Mayes, Clifford

    2002-01-01

    Many images of the teacher in the current literature on teaching and teacher reflectivity can be seen as aspects of the Jungian image of the teacher as an archetype of spirit. These images--the teacher as philosopher, prophet, Zen master, and priest--correspond to what I call dialogical, civic, ontological and incarnational spirituality,…

  3. Capturing dynamic cation hopping in cubic pyrochlores

    NASA Astrophysics Data System (ADS)

    Brooks Hinojosa, Beverly; Asthagiri, Aravind; Nino, Juan C.

    2011-08-01

    In direct contrast to recent reports, density functional theory predicts that the most stable structure of Bi2Ti2O7 pyrochlore is a cubic Fd3¯m space group by accounting for atomic displacements. The displaced Bi occupies the 96g(x,x,z) Wyckoff position with six equivalent sites, which create multiple local minima. Using nudged elastic band method, the transition states of Bi cation hopping between equivalent minima were investigated and an energy barrier between 0.11 and 0.21 eV was determined. Energy barriers associated with the motion of Bi between equivalent sites within the 96g Wyckoff position suggest the presence of dielectric relaxation in Bi2Ti2O7.

  4. Spin dynamics in geometrically frustrated antiferromagnetic pyrochlores

    NASA Astrophysics Data System (ADS)

    Gardner, J. S.; Ehlers, G.; Bramwell, S. T.; Gaulin, B. D.

    2004-03-01

    We have studied the spin dynamics of several antiferromagnetic pyrochlore oxides. These magnets are geometrically frustrated and only reach their ground states at temperatures much lower than that expected from mean field theory. Here we present data on the magnetic nature, especially the spin dynamics of Tb2Ti2O7, Gd2Ti2O7 and Y2Mo2O7. In these systems the ground states are found to be very different. Y2Mo2O7 freezes completely into a spin glass-like state, Tb2Ti2O7 is a cooperative paramagnetic and remains dynamic down to 15 mK and Gd2Ti2O7 enters a unique partially ordered state at {\\sim }1 K.

  5. Simulation of radiation damage in gadolinium pyrochlores

    NASA Astrophysics Data System (ADS)

    Todorov, Ilian T.; Purton, John A.; Allan, Neil L.; Dove, Martin T.

    2006-02-01

    We report molecular dynamics simulations of the production of radiation cascades in pyrochlores. We consider the apparently similar systems Gd2Ti2O7, Gd2Zr2O7 and Gd2Pb2O7, the first two of which have been put forward as potential materials for high-level radioactive waste storage. The effects of changing the mass of the 'primary knock-on' atom are also examined and we investigate whether the change in behaviour from Ti to Zr to Pb is largely due to the mass or the size difference between the elements. Problems associated with analysing the cascades and the damage created are discussed. There are clear differences between the three compounds. The simulations see no direct amorphization but rather a transition to the fluorite structure which is more pronounced for the Zr and Pb compounds than the Ti system. Underlying chemical trends are examined.

  6. Defect formation energy in pyrochlore: the effect of crystal size

    NASA Astrophysics Data System (ADS)

    Wang, Jianwei; Ewing, Rodney C.; Becker, Udo

    2014-09-01

    Defect formation energies of point defects of two pyrochlores Gd2Ti2O7 and Gd2Zr2O7 as a function of crystal size were calculated. Density functional theory with plane-wave basis sets and the projector-augmented wave method were used in the calculations. The results show that the defect formation energies of the two pyrochlores diverge as the size decreases to the nanometer range. For Gd2Ti2O7 pyrochlore, the defect formation energy is higher at nanometers with respect to that of the bulk, while it is lower for Gd2Zr2O7. The lowest defect formation energy for Gd2Zr2O7 is found at 15-20 Å. The different behaviors of the defect formation energies as a function of crystal size are caused by different structural adjustments around the defects as the size decreases. For both pyrochlore compositions at large sizes, the defect structures are similar to those of the bulk. As the size decreases, for Gd2Ti2O7, additional structure distortions appear at the surfaces, which cause the defect formation energy to increase. For Gd2Zr2O7, additional oxygen Frenkel pair defects are introduced, which reduce the defect formation energy. As the size further decreases, increased structure distortions occur at the surfaces, which cause the defect formation energy to increase. Based on a hypothesis that correlates the energetics of defect formation and radiation response for complex oxides, the calculated results suggest that at nanometer range Gd2Ti2O7 pyrochlore is expected to have a lower radiation tolerance, and those of Gd2Zr2O7 pyrochlore to have a higher radiation tolerance. The highest radiation tolerance for Gd2Zr2O7 pyrochlore is expected to be found at ˜2 nanometers.

  7. Integrable hierarchies of Heisenberg ferromagnet equation

    NASA Astrophysics Data System (ADS)

    Nugmanova, G.; Azimkhanova, A.

    2016-08-01

    In this paper we consider the coupled Kadomtsev-Petviashvili system. From compatibility conditions we obtain the form of matrix operators. After using a gauge transformation, obtained a new type of Lax representation for the hierarchy of Heisenberg ferromagnet equation, which is equivalent to the gauge coupled Kadomtsev-Petviashvili system.

  8. Heisenberg: Paralleling Scientific and Historical Methods

    NASA Astrophysics Data System (ADS)

    Cofield, Calla

    2007-04-01

    Werner Heisenberg is an important historical subject within the physics community partly because his actions as a human being are discussed nearly as often as his work as a physicist. But does the scientific community establish it's historical ideas with the same methods and standards as it's scientific conclusions? I interviewed Heisenberg's son, Jochen Heisenberg, a professor of physics at UNH. Despite a great amount of literature on Werner Heisenberg, only one historian has interviewed Jochen about his father and few have interviewed Werner's wife. Nature is mysterious and unpredictable, but it doesn't lie or distort like humans, and we believe it can give ``honest'' results. But are we keeping the same standards with history that we do with science? Are we holding historians to these standards and if not, is it up to scientists to not only be keepers of scientific understanding, but historical understanding as well? Shouldn't we record history by using the scientific method, by weighing the best sources of data differently than the less reliable, and are we right to be as stubborn about changing our views on history as we are about changing our views on nature?

  9. Naturalistic Misunderstanding of the Heisenberg Uncertainty Principle.

    ERIC Educational Resources Information Center

    McKerrow, K. Kelly; McKerrow, Joan E.

    1991-01-01

    The Heisenberg Uncertainty Principle, which concerns the effect of observation upon what is observed, is proper to the field of quantum physics, but has been mistakenly adopted and wrongly applied in the realm of naturalistic observation. Discusses the misuse of the principle in the current literature on naturalistic research. (DM)

  10. Quantum spin ice on the breathing pyrochlore lattice

    NASA Astrophysics Data System (ADS)

    Savary, Lucile; Wang, Xiaoqun; Kee, Hae-Young; Kim, Yong Baek; Yu, Yue; Chen, Gang

    2016-08-01

    The Coulombic quantum spin liquid in quantum spin ice is an exotic quantum phase of matter that emerges on the pyrochlore lattice and is currently actively searched for. Motivated by recent experiments on the Yb-based breathing pyrochlore material Ba3Yb2Zn5O11 , we theoretically study the phase diagram and magnetic properties of the relevant spin model. The latter takes the form of a quantum spin ice Hamiltonian on a breathing pyrochlore lattice, and we analyze the stability of the quantum spin liquid phase in the absence of the inversion symmetry which the lattice breaks explicitly at lattice sites. Using a gauge mean-field approach, we show that the quantum spin liquid occupies a finite region in parameter space. Moreover, there exists a direct quantum phase transition between the quantum spin liquid phase and featureless paramagnets, even though none of theses phases break any symmetry. At nonzero temperature, we show that breathing pyrochlores provide a much broader finite-temperature spin liquid regime than their regular counterparts. We discuss the implications of the results for current experiments and make predictions for future experiments on breathing pyrochlores.

  11. Bismuth iron titanate pyrochlores: Thermostability, structure and properties

    SciTech Connect

    Piir, I.V.; Koroleva, M.S.; Ryabkov, Yu.I.; Korolev, D.A.; Chezhina, N.V.; Semenov, V.G.; Panchuk, V.V.

    2013-08-15

    Iron containing bismuth titanates with pyrochlore structure Bi{sub 1.6}Fe{sub x}Ti{sub 2}O{sub 7−δ}, where 0.08≤x≤0.4, were obtained by ceramic procedure. The results of bough pycnometric density of the pyrochlores and of X-ray powder diffraction structure refinement points to the preference for iron atoms to occupy the Bi{sup 3+}-sites. Electric and magnetic properties were studied for single phase pyrochlores based on bismuth titanates. The magnetic ordering was studied by the methods of Mössbauer spectroscopy and magnetic susceptibility. - Graphical abstract: The ideal crystal structure of pyrochlore A{sub 2}B{sub 2}O{sub 6}O' (A—Bi{sup 3+}, Fe{sup 3+}; B—Ti{sup 4+}, Fe{sup 3+}). Highlights: • Bismuth titanate pyrochlores stable over a wide temperature range were obtained. • The distribution of Fe{sup 3+} over various sites was determined. • The obtained systems were characterized by magnetic susceptibility, Mössbauer spectroscopy and conductivity.

  12. Frustration under pressure: Exotic magnetism in new pyrochlore oxides

    SciTech Connect

    Wiebe, C. R.; Hallas, A. M.

    2015-04-01

    Pyrochlore structures, of chemical formula A{sub 2}B{sub 2}O{sub 7} (A and B are typically trivalent and tetravalent ions, respectively), have been the focus of much activity in the condensed matter community due to the ease of substitution of rare earth and transition metal ions upon the two interpenetrating corner-shared tetrahedral lattices. Over the last few decades, superconductivity, spin liquid states, spin ice states, glassy states in the absence of chemical disorder, and metal-insulator transitions have all been discovered in these materials. Geometric frustration plays a role in the relevant physics of all of these phenomena. In the search for new pyrochlore materials, it is the R{sub A}/R{sub B} cation radius ratio which determines the stability of the lattice over the defect fluorite structure in the lower limit. Under ambient pressure, the pyrochlores are stable for 1.36 ≤ R{sub A}/R{sub B} ≤ 1.71. However, using high pressure synthesis techniques (1-10 GPa of pressure), metastable pyrochlores exist up to R{sub A}/R{sub B} = 2.30. Many of these compounds are stable on a timescale of years after synthesis, and provide a means to greatly enhance exchange, and thus test theories of quantum magnetism and search for new phenomena. Within this article, we review new pyrochlore compounds synthesized via high pressure techniques and show how the ground states are extremely sensitive to chemical pressure.

  13. Arranging ISO 13606 archetypes into a knowledge base.

    PubMed

    Kopanitsa, Georgy

    2014-01-01

    To enable the efficient reuse of standard based medical data we propose to develop a higher level information model that will complement the archetype model of ISO 13606. This model will make use of the relationships that are specified in UML to connect medical archetypes into a knowledge base within a repository. UML connectors were analyzed for their ability to be applied in the implementation of a higher level model that will establish relationships between archetypes. An information model was developed using XML Schema notation. The model allows linking different archetypes of one repository into a knowledge base. Presently it supports several relationships and will be advanced in future. PMID:25160140

  14. Ab initio determination of spin Hamiltonians with anisotropic exchange interactions: The case of the pyrochlore ferromagnet Lu2V2O7

    NASA Astrophysics Data System (ADS)

    Riedl, Kira; Guterding, Daniel; Jeschke, Harald O.; Gingras, Michel J. P.; Valentí, Roser

    2016-07-01

    We present a general framework for deriving effective spin Hamiltonians of correlated magnetic systems based on a combination of relativistic ab initio density functional theory calculations, exact diagonalization of a generalized Hubbard Hamiltonian on finite clusters, and spin projections onto the low-energy subspace. A key motivation is to determine anisotropic bilinear exchange couplings in materials of interest. As an example, we apply this method to the pyrochlore Lu2V2O7 where the vanadium ions form a lattice of corner-sharing spin-1/2 tetrahedra. In this compound, anisotropic Dzyaloshinskii-Moriya interactions (DMIs) play an essential role in inducing a magnon Hall effect. We obtain quantitative estimates of the nearest-neighbor Heisenberg exchange, the DMI, and the symmetric part of the anisotropic exchange tensor. Finally, we compare our results with experimental ones on the Lu2V2O7 compound.

  15. Incorporation of uranium in pyrochlore oxides and pressure-induced phase transitions

    SciTech Connect

    Zhang, F.X.; Lang, M.; Tracy, C.; Ewing, R.C.; Gregg, D.J.; Lumpkin, G.R.

    2014-11-15

    Uranium-doped gadolinium zirconates with pyrochlore structure were studied at ambient and high-pressure conditions up to 40 GPa. The bonding environment of uranium in the structure was determined by x-ray photoelectron and Raman spectroscopies and x-ray diffraction. The uranium valence for samples prepared in air is mainly U{sup 6+}, but U{sup 4+} is present in pyrochlores fabricated in an argon atmosphere. Rietveld refinement of the XRD pattern suggests that uranium ions in pyrochlores are on the 16d site in 6-fold coordination with oxygen. At pressures greater than 22 GPa, the pyrochlore structure transformed to a cotunnite-type phase. The cotunnite high-pressure phase transformed to a defect fluorite structure on the release of pressure. - Graphical abstract: In U-bearing pyrochlore, U ions mainly occupy the 16d site and replace the smaller Zr{sup 4+}, part of the oxygen will occupy the 8b site, which is empty to most pyrochlores. At pressure of 22 GPa, the pyrochlore lattice is not stable and transforms to a cotunnite-type structure. The high-pressure structure is not stable and transform to a fluorite or back to the pyrochlore structure when pressure is released. - Highlights: • We found that U ions mainly occupy the smaller cation site in U-bearing pyrochlore. • Pyrochlore structure is not stable at pressure of more than 20 GPa. • The quenched sample has a pyrochlore or a disordered fluorite structure.

  16. The Homophilic Domain – An Immunological Archetype

    PubMed Central

    Kohler, Heinz; Bayry, Jagadeesh; Kaveri, Srinivas V.

    2016-01-01

    The homophilic potential emerges as an important biological principle to boost the potency of immunoglobulins. Since homophilic antibodies in human and mouse sera exist prior environmental exposure, they are part of the natural antibody repertoire. Nevertheless, hemophilic properties are also identified in induced antibody repertoire. The use of homophilicity of antibodies in the adaptive immunity signifies an archetypic antibody structure. The unique feature of homophilicity in the antibody repertoire also highlights an important mechanism to boost the antibody potency to protect against infection and atherosclerosis as well to treat cancer patients. PMID:27047493

  17. The Homophilic Domain - An Immunological Archetype.

    PubMed

    Kohler, Heinz; Bayry, Jagadeesh; Kaveri, Srinivas V

    2016-01-01

    The homophilic potential emerges as an important biological principle to boost the potency of immunoglobulins. Since homophilic antibodies in human and mouse sera exist prior environmental exposure, they are part of the natural antibody repertoire. Nevertheless, hemophilic properties are also identified in induced antibody repertoire. The use of homophilicity of antibodies in the adaptive immunity signifies an archetypic antibody structure. The unique feature of homophilicity in the antibody repertoire also highlights an important mechanism to boost the antibody potency to protect against infection and atherosclerosis as well to treat cancer patients.

  18. [Facial graft, archetype of microsurgical innovation?].

    PubMed

    Devauchelle, B; Testelin, S; Dakpe, S; Lengelé, B; Dubernard, J-M

    2010-10-01

    Is innovation breaking of the way of thinking, breaker of taboos, concretisation of chimeras or simple benefit of an ineluctable evolution? The surgical act should be considered as innovation itself? From the first facial allotransplantation, innovation is declined in various ways, which could constitute the different answers regarding the planning and management to prepare such surgery, the realisation of the transplantation and also the multiple developments in terms of science and medicine. It is exactly in that meaning that could be really mentioned the term archetypal.

  19. Two Archetypes of Motor Control Research

    PubMed Central

    Latash, Mark L.

    2010-01-01

    This reply to the Commentaries is focused on two archetypes of motor control research, one based on physics and physiology and the other based on control theory and ideas of neural computations. The former approach, represented by the equilibrium-point hypothesis, strives to discover the physical laws and salient physiological variables that make purposeful coordinated movements possible. The latter approach, represented by the ideas of internal models and optimal control, tries to apply methods of control developed for man-made inanimate systems to the human body. Specific issues related to control with subthreshold membrane depolarization, motor redundancy, and the idea of synergies are briefly discussed. PMID:21479107

  20. The Contextualization of Archetypes: Clinical Template Governance.

    PubMed

    Pedersen, Rune; Ulriksen, Gro-Hilde; Ellingsen, Gunnar

    2015-01-01

    This paper is a status report from a large-scale openEHR-based EPR project from the North Norway Regional Health Authority. It concerns the standardization of a regional ICT portfolio and the ongoing development of a new process oriented EPR systems encouraged by the unfolding of a national repository for openEHR archetypes. Subject of interest; the contextualization of clinical templates is governed over multiple national boundaries which is complex due to the dependency of clinical resources. From the outset of this, we are interested in how local, regional, and national organizers maneuver to standardize while applying OpenEHR technology. PMID:26262546

  1. OWL-based reasoning methods for validating archetypes.

    PubMed

    Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás

    2013-04-01

    Some modern Electronic Healthcare Record (EHR) architectures and standards are based on the dual model-based architecture, which defines two conceptual levels: reference model and archetype model. Such architectures represent EHR domain knowledge by means of archetypes, which are considered by many researchers to play a fundamental role for the achievement of semantic interoperability in healthcare. Consequently, formal methods for validating archetypes are necessary. In recent years, there has been an increasing interest in exploring how semantic web technologies in general, and ontologies in particular, can facilitate the representation and management of archetypes, including binding to terminologies, but no solution based on such technologies has been provided to date to validate archetypes. Our approach represents archetypes by means of OWL ontologies. This permits to combine the two levels of the dual model-based architecture in one modeling framework which can also integrate terminologies available in OWL format. The validation method consists of reasoning on those ontologies to find modeling errors in archetypes: incorrect restrictions over the reference model, non-conformant archetype specializations and inconsistent terminological bindings. The archetypes available in the repositories supported by the openEHR Foundation and the NHS Connecting for Health Program, which are the two largest publicly available ones, have been analyzed with our validation method. For such purpose, we have implemented a software tool called Archeck. Our results show that around 1/5 of archetype specializations contain modeling errors, the most common mistakes being related to coded terms and terminological bindings. The analysis of each repository reveals that different patterns of errors are found in both repositories. This result reinforces the need for making serious efforts in improving archetype design processes. PMID:23246613

  2. Magnetic order in the pyrochlore iridates

    NASA Astrophysics Data System (ADS)

    Disseler, Steven Michael Thomas

    This thesis is concerned with experimentally determining the magnetic and electronic states in a unique class of transition metal oxides known as the pyrochlore iridates, A2Ir2O 7 (A = Y or Rare earth). The extended nature of the 5d Ir orbitals in the iridates places these materials in a regime of intermediate electron correlation and large spin-orbit interaction such that this system may host several novel or topological states of matter which may be perturbed by incorporating different A-species. Additionally, the pyrochlore structure is geometrically frustrated and has been long been studied as a potential host of a number of exotic magnetic phenomenon. However, even after years of intense theoretical and experimental interest many fundamental questions still remain about the nature of the magnetic ground sates in this series which are of vital importance in understanding the roles of various interactions and potential of such novel phenomenon. The primary aim of this thesis is therefore to determine how magnetic order develops on the Ir sublattice in this series, particularly how it is perturbed through variation of the crystalline structure, magnetism of the A-site ions, and presence of mobile charges. This thesis is the first comprehensive experimental study of these effects which has utilized several complementary experimental probes of both bulk and local magnetism in a number of compounds. The techniques presented in this work include magnetotransport, bulk magnetization, elastic neutron scattering, and muon spin relaxation (muSR) measurements. All of the three compounds studied in this work (A = Y, Yb, and Nd) are shown to definitively exhibit long-range magnetic order on the Ir sublattice, which has previously only been inferred based on studies of other compounds. The compounds Y 2Ir2O7 and Yb2Ir2O 7 are correlated insulators at low temperature and are found to have identical configuration of the Ir moments, despite the presence of the large localized

  3. Chirality operators for Heisenberg spin systems

    SciTech Connect

    Subrahmanyam, V. )

    1994-09-01

    The ground state of closed Heisenberg spin chains with an odd number of sites has a chiral degeneracy, in addition to a twofold Kramers degeneracy. A nonzero chirality implies that the spins are not coplanar, and is a measure of handedness. The chirality operator, which can be treated as a spin-1/2 operator, is explicitly constructed in terms of the spin operators, and is given as commutator of permutation operators.

  4. Heisenberg necklace model in a magnetic field

    NASA Astrophysics Data System (ADS)

    Tsvelik, A. M.; Zaliznyak, I. A.

    2016-08-01

    We study the low-energy sector of the Heisenberg necklace model. Using the field-theory methods, we estimate how the coupling of the electronic spins with the paramagnetic Kondo spins affects the overall spin dynamics and evaluate its dependence on a magnetic field. We are motivated by the experimental realizations of the spin-1/2 Heisenberg chains in SrCuO2 and Sr2CuO3 cuprates, which remain one-dimensional Luttinger liquids down to temperatures much lower than the in-chain exchange coupling J . We consider the perturbation of the energy spectrum caused by the interaction γ with nuclear spins (I =3 /2 ) present on the same sites. We find that the resulting necklace model has a characteristic energy scale, Λ ˜J1 /3(γI ) 2 /3 , at which the coupling between (nuclear) spins of the necklace and the spins of the Heisenberg chain becomes strong. This energy scale is insensitive to a magnetic field B . For μBB >Λ we find two gapless bosonic modes that have different velocities, whose ratio at strong fields approaches a universal number, √{2 }+1 .

  5. SUGRA new inflation with Heisenberg symmetry

    SciTech Connect

    Antusch, Stefan; Cefalà, Francesco E-mail: stefan.antusch@unibas.ch

    2013-10-01

    We propose a realisation of ''new inflation'' in supergravity (SUGRA), where the flatness of the inflaton potential is protected by a Heisenberg symmetry. Inflation can be associated with a particle physics phase transition, with the inflaton being a (D-flat) direction of Higgs fields which break some symmetry at high energies, e.g. of GUT Higgs fields or of Higgs fields for flavour symmetry breaking. This is possible since compared to a shift symmetry, which is usually used to protect a flat inflaton potential, the Heisenberg symmetry is compatible with a (gauge) non-singlet inflaton field. In contrast to conventional new inflation models in SUGRA, where the predictions depend on unknown parameters of the Kaehler potential, the model with Heisenberg symmetry makes discrete predictions for the primordial perturbation parameters which depend only on the order n at which the inflaton appears in the effective superpotential. The predictions for the spectral index n{sub s} can be close to the best-fit value of the latest Planck 2013 results.

  6. Exploring Ethical Dilemmas Using the "Drifting Goals" Archetype

    ERIC Educational Resources Information Center

    Bardoel, E. Anne; Haslett, Tim

    2006-01-01

    This article demonstrates how the system archetype "drifting goals" can be used in the classroom to explore ethical dilemmas. System archetypes provide a framework that shifts the focus from seeing ethical dilemmas as stemming solely from the acts of individuals to exploring the systemic structures that are responsible for generic patterns of…

  7. Wounded Leader: An Archetypal Embodiment of Compassionate Transcendent Leadership

    ERIC Educational Resources Information Center

    Mears, Kathryn

    2009-01-01

    The purpose of this study was to seek to further the formation of the emerging transcendent leadership model by exploring the archetypal image identified as wounded leader. The wounded leader archetype is introduced as a leadership style of influence that fits well within the framework of the transcendent leadership model. This study…

  8. Identification of Nanoparticle Prototypes and Archetypes.

    PubMed

    Fernandez, Michael; Barnard, Amanda S

    2015-12-22

    High-throughput (HT) computational characterization of nanomaterials is poised to accelerate novel material breakthroughs. The number of possible nanomaterials is increasing exponentially along with their complexity, and so statistical and information technology will play a fundamental role in rationalizing nanomaterials HT data. We demonstrate that multivariate statistical analysis of heterogeneous ensembles can identify the truly significant nanoparticles and their most relevant properties. Virtual samples of diamond nanoparticles and graphene nanoflakes are characterized using clustering and archetypal analysis, where we find that saturated particles are defined by their geometry, while nonsaturated nanoparticles are defined by their carbon chemistry. At the complex hull of the nanostructure spaces, a combination of complex archetypes can efficiency describe a large number of members of the ensembles, whereas the regular shapes that are typically assumed to be representative can only describe a small set of the most regular morphologies. This approach provides a route toward the characterization of computationally intractable virtual nanomaterial spaces, which can aid nanomaterials discovery in the foreseen big data scenario. PMID:26575441

  9. Radiation-induced amorphization of rare-earth titanate pyrochlores

    NASA Astrophysics Data System (ADS)

    Lian, Jie; Chen, Jian; Wang, L. M.; Ewing, Rodney C.; Farmer, J. Matt; Boatner, Lynn A.; Helean, K. B.

    2003-10-01

    Single crystals of the entire series of A2Ti2O7 (A=Sm to Lu, and Y) pyrochlore compounds were irradiated by 1-MeV Kr+ ions at temperatures from 293 to 1073 K, and the microstructure evolution, as a function of increasing radiation fluence, was characterized using in situ transmission electron microscopy (TEM). The critical amorphization temperature, Tc, generally increases from ˜480 to ˜1120 K with increasing A-site cation size (e.g., 0.977 Å for Lu3+ to 1.079 Å for Sm3+). An abnormally high susceptibility to ion beam damage was found for Gd2Ti2O7 (with the highest Tc of ˜1120 K). Factors influencing the response of titanate pyrochlores to ion irradiation-induced amorphization are discussed in terms of cation radius ratio, defect formation, and the tendency to undergo an order-disorder transition to the defect-fluorite structure. The resistance of the pyrochlore structure to ion beam-induced amorphization is not only affected by the relative sizes of the A- and B-site cations, but also the cation electronic configuration and the structural disorder. Pyrochlore compositions that have larger structural deviations from the ideal fluorite structure, as evidenced by the smaller 48f oxygen positional parameter, x, are more sensitive to ion beam-induced amorphization.

  10. Are archetypes transmitted more by culture than biology? Questions arising from conceptualizations of the archetype.

    PubMed

    Roesler, Christian

    2012-04-01

    The archetype is one of the most important, if not the central concept of analytical psychology. Nevertheless from the beginning the concept was controversial. This paper attempts to review the debate around the term archetype and tries to point out some of the main problems the concept has in the light of contemporary knowledge especially in genetics and neurosciences. It becomes clear that for its use in the practice of Jungian psychotherapy the element of universality in the concept of archetypes is crucial. However, it must be concluded that there is still no firm scientific foundation for the claim that complex symbolic patterns (as for example the myth of the hero) can be transmitted in a way that every human individual has access to them. The paper attempts to show possible ways in which this transmission may be more successfully conceptualized. I would like to have Jung have the last word here. We find a hint in Jung's work where he opens up to ideas much like the ones I have developed here, and this is where Jung says: culture is part of man's nature.

  11. Are archetypes transmitted more by culture than biology? Questions arising from conceptualizations of the archetype.

    PubMed

    Roesler, Christian

    2012-04-01

    The archetype is one of the most important, if not the central concept of analytical psychology. Nevertheless from the beginning the concept was controversial. This paper attempts to review the debate around the term archetype and tries to point out some of the main problems the concept has in the light of contemporary knowledge especially in genetics and neurosciences. It becomes clear that for its use in the practice of Jungian psychotherapy the element of universality in the concept of archetypes is crucial. However, it must be concluded that there is still no firm scientific foundation for the claim that complex symbolic patterns (as for example the myth of the hero) can be transmitted in a way that every human individual has access to them. The paper attempts to show possible ways in which this transmission may be more successfully conceptualized. I would like to have Jung have the last word here. We find a hint in Jung's work where he opens up to ideas much like the ones I have developed here, and this is where Jung says: culture is part of man's nature. PMID:22444357

  12. Clinical data interoperability based on archetype transformation.

    PubMed

    Costa, Catalina Martínez; Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás

    2011-10-01

    The semantic interoperability between health information systems is a major challenge to improve the quality of clinical practice and patient safety. In recent years many projects have faced this problem and provided solutions based on specific standards and technologies in order to satisfy the needs of a particular scenario. Most of such solutions cannot be easily adapted to new scenarios, thus more global solutions are needed. In this work, we have focused on the semantic interoperability of electronic healthcare records standards based on the dual model architecture and we have developed a solution that has been applied to ISO 13606 and openEHR. The technological infrastructure combines reference models, archetypes and ontologies, with the support of Model-driven Engineering techniques. For this purpose, the interoperability infrastructure developed in previous work by our group has been reused and extended to cover the requirements of data transformation.

  13. Efficient propagation of archetype BK and JC polyomaviruses.

    PubMed

    Broekema, Nicole M; Imperiale, Michael J

    2012-01-20

    BKPyV and JCPyV are closely related, ubiquitous human pathogens that cause disease in immunocompromised patients. The DNA sequence of the regulatory regions distinguishes two forms of these viruses, designated archetype and rearranged. Although cell culture systems exist for rearranged BKPyV and JCPyV, currently there is no robust cell culture system to study the archetype viruses. Large T antigen (TAg) is a virally encoded protein required to initiate viral DNA synthesis. Because archetype virus produces undetectable levels of TAg, we hypothesized that TAg overexpression would stimulate archetype virus replication. Efficient propagation of the archetype forms of BKPyV and JCPyV was observed in 293TT cells, human embryonic kidney cells overexpressing SV40 TAg. Importantly, the archetypal structure of the regulatory region was maintained during viral growth. Significant replication was not observed for Merkel cell, KI, or WU polyomaviruses. 293TT cells provide a means of propagating archetype BKPyV and JCPyV for detailed study.

  14. Clinical coverage of an archetype repository over SNOMED-CT.

    PubMed

    Yu, Sheng; Berry, Damon; Bisbal, Jesus

    2012-06-01

    Clinical archetypes provide a means for health professionals to design what should be communicated as part of an Electronic Health Record (EHR). An ever-growing number of archetype definitions follow this health information modelling approach, and this international archetype resource will eventually cover a large number of clinical concepts. On the other hand, clinical terminology systems that can be referenced by archetypes also have a wide coverage over many types of health-care information. No existing work measures the clinical content coverage of archetypes using terminology systems as a metric. Archetype authors require guidance to identify under-covered clinical areas that may need to be the focus of further modelling effort according to this paradigm. This paper develops a first map of SNOMED-CT concepts covered by archetypes in a repository by creating a so-called terminological Shadow. This is achieved by mapping appropriate SNOMED-CT concepts from all nodes that contain archetype terms, finding the top two category levels of the mapped concepts in the SNOMED-CT hierarchy, and calculating the coverage of each category. A quantitative study of the results compares the coverage of different categories to identify relatively under-covered as well as well-covered areas. The results show that the coverage of the well-known National Health Service (NHS) Connecting for Health (CfH) archetype repository on all categories of SNOMED-CT is not equally balanced. Categories worth investigating emerged at different points on the coverage spectrum, including well-covered categories such as Attributes, Qualifier value, under-covered categories such as Microorganism, Kingdom animalia, and categories that are not covered at all such as Cardiovascular drug (product).

  15. Validating archetypes for the Multiple Sclerosis Functional Composite

    PubMed Central

    2014-01-01

    Background Numerous information models for electronic health records, such as openEHR archetypes are available. The quality of such clinical models is important to guarantee standardised semantics and to facilitate their interoperability. However, validation aspects are not regarded sufficiently yet. The objective of this report is to investigate the feasibility of archetype development and its community-based validation process, presuming that this review process is a practical way to ensure high-quality information models amending the formal reference model definitions. Methods A standard archetype development approach was applied on a case set of three clinical tests for multiple sclerosis assessment: After an analysis of the tests, the obtained data elements were organised and structured. The appropriate archetype class was selected and the data elements were implemented in an iterative refinement process. Clinical and information modelling experts validated the models in a structured review process. Results Four new archetypes were developed and publicly deployed in the openEHR Clinical Knowledge Manager, an online platform provided by the openEHR Foundation. Afterwards, these four archetypes were validated by domain experts in a team review. The review was a formalised process, organised in the Clinical Knowledge Manager. Both, development and review process turned out to be time-consuming tasks, mostly due to difficult selection processes between alternative modelling approaches. The archetype review was a straightforward team process with the goal to validate archetypes pragmatically. Conclusions The quality of medical information models is crucial to guarantee standardised semantic representation in order to improve interoperability. The validation process is a practical way to better harmonise models that diverge due to necessary flexibility left open by the underlying formal reference model definitions. This case study provides evidence that both

  16. Frustrated 3×3 Heisenberg antiferromagnets

    NASA Astrophysics Data System (ADS)

    Moustanis, P. N.

    2016-08-01

    The full energy spectrum and the exact thermodynamic results of the antiferromagnetic Heisenberg Hamiltonian of the 3×3 triangular and the frustrated square lattice with periodic boundary conditions and s=1/2 are obtained. To this end the method of hierarchy of algebras is employed. It was found that the ground state of the 3×3 frustrated square lattice is a Resonating Valence Bond (RVB) state. Thermodynamic properties, like the specific heat, magnetic susceptibility, the thermal average of the square of the total Sz and entropy, for these two lattices are presented.

  17. Heisenberg scaling in Gaussian quantum metrology

    NASA Astrophysics Data System (ADS)

    Friis, Nicolai; Skotiniotis, Michalis; Fuentes, Ivette; Dür, Wolfgang

    2015-08-01

    We address the issue of precisely estimating small parameters encoded in a general linear transformation of the modes of a bosonic quantum field. Such Bogoliubov transformations frequently appear in the context of quantum optics. We provide a set of instructions for computing the quantum Fisher information for arbitrary pure initial states. We show that the maximally achievable precision of estimation is inversely proportional to the squared average particle number and that such Heisenberg scaling requires nonclassical but not necessarily entangled states. Our method further allows us to quantify losses in precision arising from being able to monitor only finitely many modes, for which we identify a lower bound.

  18. Thermodynamic properties of Heisenberg magnetic systems

    NASA Astrophysics Data System (ADS)

    Qin, Wei; Wang, Huai-Yu; Long, Gui-Lu

    2014-03-01

    In this paper, we present a comprehensive investigation of the effects of the transverse correlation function (TCF) on the thermodynamic properties of Heisenberg antiferromagnetic (AFM) and ferromagnetic (FM) systems with cubic lattices. The TCF of an FM system is positive and increases with temperature, while that of an AFM system is negative and decreases with temperature. The TCF lowers internal energy, entropy and specific heat. It always raises the free energy of an FM system but raises that of an AFM system only above a specific temperature when the spin quantum number is S >= 1. Comparisons between the effects of the TCFs on the FM and AFM systems are made where possible.

  19. Discrete flavour symmetries from the Heisenberg group

    NASA Astrophysics Data System (ADS)

    Floratos, E. G.; Leontaris, G. K.

    2016-04-01

    Non-abelian discrete symmetries are of particular importance in model building. They are mainly invoked to explain the various fermion mass hierarchies and forbid dangerous superpotential terms. In string models they are usually associated to the geometry of the compactification manifold and more particularly to the magnetised branes in toroidal compactifications. Motivated by these facts, in this note we propose a unified framework to construct representations of finite discrete family groups based on the automorphisms of the discrete and finite Heisenberg group. We focus in particular, on the PSL2 (p) groups which contain the phenomenologically interesting cases.

  20. Spin-wave spectrum of the quantum ferromagnet on the pyrochlore lattice Lu2V2O7.

    PubMed

    Mena, M; Perry, R S; Perring, T G; Le, M D; Guerrero, S; Storni, M; Adroja, D T; Rüegg, Ch; McMorrow, D F

    2014-07-25

    Neutron inelastic scattering has been used to probe the spin dynamics of the quantum (S=1/2) ferromagnet on the pyrochlore lattice Lu(2)V(2)O(7). Well-defined spin waves are observed at all energies and wave vectors, allowing us to determine the parameters of the Hamiltonian of the system. The data are found to be in excellent overall agreement with a minimal model that includes a nearest-neighbor Heisenberg exchange J = 8.22(2) meV and a Dzyaloshinskii-Moriya interaction (DMI) D = 1.5(1) meV. The large DMI term revealed by our study is broadly consistent with the model originally used to explain the magnon Hall effect in this compound [Onose et al., Science 329, 297 (2010) and Ideue et al., Phys. Rev. B 85, 134411 (2012)]. However, our ratio of D/J = 0.18(1) is roughly half of their value, and is much larger than those found in other theoretical studies [Xiang et al., Phys. Rev. B 83, 174402 (2011) and Mook et al., Phys. Rev. B 89,134409 (2014)].

  1. Evolution of cooperation with similarity to an archetype.

    PubMed

    Houy, Nicolas

    2013-09-01

    We use the framework of Colman with a Prisoner's Dilemma game and an evolutionary agent-based algorithm in order to study the evolution of cooperation and discrimination. We assume that players can discriminate on the basis of the phenotypic distance to an archetype, linked itself with a given behaviour in the game. However, we do not impose that the archetype corresponds to a conditionally cooperative behaviour. We show that cooperation can become the norm and discrimination can evolve spontaneously with no other assumption. For some archetypes, cooperation can even evolve faster and with more intensity than in the similarity-based case studied in Colman et al., 2012.

  2. Evolution of cooperation with similarity to an archetype.

    PubMed

    Houy, Nicolas

    2013-09-01

    We use the framework of Colman with a Prisoner's Dilemma game and an evolutionary agent-based algorithm in order to study the evolution of cooperation and discrimination. We assume that players can discriminate on the basis of the phenotypic distance to an archetype, linked itself with a given behaviour in the game. However, we do not impose that the archetype corresponds to a conditionally cooperative behaviour. We show that cooperation can become the norm and discrimination can evolve spontaneously with no other assumption. For some archetypes, cooperation can even evolve faster and with more intensity than in the similarity-based case studied in Colman et al., 2012. PMID:23623950

  3. q-bosons and the Lie-deformed Heisenberg algebra

    NASA Astrophysics Data System (ADS)

    Pan, Hui-yun; Zhao, Zu Sen

    1998-02-01

    It is shown that the non-Hermitian realization of a Lie-deformed Heisenberg algebra given by Jannussis et al. is closely related with the q-Heisenberg-Weyl algebra of Biedenharn and Macfarlane with q being a phase ( q = eiθ, with θ real). The physical implications of this result are stressed.

  4. Science 101: What, Exactly, Is the Heisenberg Uncertainty Principle?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2016-01-01

    Bill Robertson is the author of the NSTA Press book series, "Stop Faking It! Finally Understanding Science So You Can Teach It." In this month's issue, Robertson describes and explains the Heisenberg Uncertainty Principle. The Heisenberg Uncertainty Principle was discussed on "The Big Bang Theory," the lead character in…

  5. Radiation damage effects in candidate titanates for Pu disposition: Pyrochlore

    NASA Astrophysics Data System (ADS)

    Strachan, D. M.; Scheele, R. D.; Buck, E. C.; Icenhower, J. P.; Kozelisky, A. E.; Sell, R. L.; Elovich, R. J.; Buchmiller, W. C.

    2005-10-01

    Laboratory experiments on titanate ceramics were performed to verify whether certain assumptions are valid regarding the swelling, chemical durability, and microcracking that might occur as 239Pu decays. Titanate ceramics are the material of choice for the immobilization of surplus weapons-grade Pu. The short-lived isotope 238Pu, was incorporated into the ceramic formulation to accelerate the effects of radiation-induced damage. We report on the effects of this damage on the density (volumetric swelling <6%), crystal structure of pyrochlore-bearing specimens (amorphous after about 2 × 1018 α/g), and dissolution (no change from the fully crystalline specimen). Even though the specimens became amorphous during the tests, there was no evidence for microcracking in the photomicrographs from the scanning electron microscope. Thus, although pyrochlore is susceptible to radiation-induced damage, the material remains chemically and physically viable as a material for immobilizing surplus weapons-grade Pu.

  6. Goethe's Archetype and the romantic concept of the self.

    PubMed

    Pratt, V; Brook, I

    1996-09-01

    This paper attempts to illuminate Goethe's concept of an archetype by setting it alongside the concept of the self that was being articulated at the same time, also by writers of the Romantic movement. The Romantic concept of the self expresses a new concept of the self as a 'core' plus an expression of the core: and it is the same 'core plus expression' idea that is embodied in the Goethean archetype. Goethe's archetype is not simply a 'plan'. It is a kind of agent at the heart of a thing, striving for self expression, and to this end driving the thing's development. Both Romantic self and archetype reflect the wider attempt to reinstate the concept of action in our understanding of things and happenings in general. The root idea of there being at the heart of a living thing an agent pursuing a goal remains in the modern concept of the organism.

  7. Archetypal dynamics, emergent situations, and the reality game.

    PubMed

    Sulis, William

    2010-07-01

    The classical approach to the modeling of reality is founded upon its objectification. Although successful dealing with inanimate matter, objectification has proven to be much less successful elsewhere, sometimes to the point of paradox. This paper discusses an approach to the modeling of reality based upon the concept of process as formulated within the framework of archetypal dynamics. Reality is conceptualized as an intermingling of information-transducing systems, together with the semantic frames that effectively describe and ascribe meaning to each system, along with particular formal representations of same which constitute the archetypes. Archetypal dynamics is the study of the relationships between systems, frames and their representations and the flow of information among these different entities. In this paper a specific formal representation of archetypal dynamics using tapestries is given, and a dynamics is founded upon this representation in the form of a combinatorial game called a reality game. Some simple examples are presented. PMID:20587299

  8. [Essential data set's archetypes for nursing care of endometriosis patients].

    PubMed

    Spigolon, Dandara Novakowski; Moro, Claudia Maria Cabral

    2012-12-01

    This study aimed to develop an Essential Data Set for Nursing Care of Patients with Endometriosis (CDEEPE), represented by archetypes. An exploratory applied research with specialists' participation that was carried out at Heath Informatics Laboratory of PUCPR, between February and November of 2010. It was divided in two stages: CDEEPE construction and evaluation including Nursing Process phases and Basic Human Needs, and archetypes development based on this data set. CDEEPE was evaluated by doctors and nurses with 95.9% of consensus and containing 51 data items. The archetype "Perception of Organs and Senses" was created to represents this data set. This study allowed identifying important information for nursing practices contributing to computerization and application of nursing process during care. The CDEEPE was the basis for archetype creation, that will make possible structured, organized, efficient, interoperable, and semantics records.

  9. [Essential data set's archetypes for nursing care of endometriosis patients].

    PubMed

    Spigolon, Dandara Novakowski; Moro, Claudia Maria Cabral

    2012-12-01

    This study aimed to develop an Essential Data Set for Nursing Care of Patients with Endometriosis (CDEEPE), represented by archetypes. An exploratory applied research with specialists' participation that was carried out at Heath Informatics Laboratory of PUCPR, between February and November of 2010. It was divided in two stages: CDEEPE construction and evaluation including Nursing Process phases and Basic Human Needs, and archetypes development based on this data set. CDEEPE was evaluated by doctors and nurses with 95.9% of consensus and containing 51 data items. The archetype "Perception of Organs and Senses" was created to represents this data set. This study allowed identifying important information for nursing practices contributing to computerization and application of nursing process during care. The CDEEPE was the basis for archetype creation, that will make possible structured, organized, efficient, interoperable, and semantics records. PMID:23596913

  10. Nursing Minimum Data Set Based on EHR Archetypes Approach.

    PubMed

    Spigolon, Dandara N; Moro, Cláudia M C

    2012-01-01

    The establishment of a Nursing Minimum Data Set (NMDS) can facilitate the use of health information systems. The adoption of these sets and represent them based on archetypes are a way of developing and support health systems. The objective of this paper is to describe the definition of a minimum data set for nursing in endometriosis represent with archetypes. The study was divided into two steps: Defining the Nursing Minimum Data Set to endometriosis, and Development archetypes related to the NMDS. The nursing data set to endometriosis was represented in the form of archetype, using the whole perception of the evaluation item, organs and senses. This form of representation is an important tool for semantic interoperability and knowledge representation for health information systems. PMID:24199126

  11. Representation and simulation for pyrochlore lattice via Monte Carlo technique

    NASA Astrophysics Data System (ADS)

    Passos, André Luis; de Albuquerque, Douglas F.; Filho, João Batista Santos

    2016-05-01

    This work presents a representation of the Kagome and pyrochlore lattices using Monte Carlo simulation as well as some results of the critical properties. These lattices are composed corner sharing triangles and tetrahedrons respectively. The simulation was performed employing the Cluster Wolf Algorithm for the spin updates through the standard ferromagnetic Ising Model. The determination of the critical temperature and exponents was based on the Histogram Technique and the Finite-Size Scaling Theory.

  12. New space vehicle archetypes for human planetary missions

    NASA Technical Reports Server (NTRS)

    Sherwood, Brent

    1991-01-01

    Contemporary, archetypal, crew-carrying spacecraft concepts developed for NASA are presented for: a lunar transportation system, two kinds of Mars landers, and five kinds of Mars transfer vehicles. These cover the range of propulsion technologies and mission modes of interest for the Space Exploration Initiative, and include both aerobraking and artificial gravity as appropriate. They comprise both upgrades of extant archetypes and completely new ones. Computer solid models, configurations and mass statements are presented for each.

  13. The role of surfaces, chemical interfaces, and disorder on plutonium incorporation in pyrochlores.

    PubMed

    Perriot, Romain; Dholabhai, Pratik P; Uberuaga, Blas P

    2016-08-17

    Pyrochlores, a class of complex oxides with formula A2B2O7, are one of the candidates for nuclear waste encapsulation, due to the natural occurrence of actinide-bearing pyrochlore minerals and laboratory observations of high radiation tolerance. In this work, we use atomistic simulations to determine the role of surfaces, chemical interfaces, and cation disorder on the plutonium immobilization properties of pyrochlores as a function of pyrochlore chemistry. We find that both Pu(3+) and Pu(4+) segregate to the surface for the four low-index pyrochlore surfaces considered, and that the segregation energy varies with the chemistry of the compound. We also find that pyrochlore/pyrochlore bicrystals A2B2O7/A2'B2'O7 can be used to immobilize Pu(3+) and Pu(4+) either in the same or separate phases of the compound, depending on the chemistry of the material. Finally, we find that Pu(4+) segregates to the disordered phase of an order/disorder bicrystal, driven by the occurrence of local oxygen-rich environments. However, Pu(3+) is weakly sensitive to the oxygen environment, and therefore only slightly favors the disordered phase. This behavior suggests that, at some concentration, Pu incorporation can destabilize the pyrochlore structure. Together, these results provide new insight into the ability of pyrochlore compounds to encapsulate Pu and suggest new considerations in the development of waste forms based on pyrochlores. In particular, the phase structure of a multi-phase pyrochlore composite can be used to independently getter decay products based on their valence and size. PMID:27480791

  14. Antiferromagnetic Heisenberg spin-1 chain: Magnetic susceptibility of the Haldane chain described using scaling

    NASA Astrophysics Data System (ADS)

    Souletie, Jean; Drillon, Marc; Rabu, Pierre; Pati, Swapan K.

    2004-08-01

    The phenomenological expression χT/(Ng2μB2/k)=C1nexp(-W1n/T)+C2nexp(-W2n/T) describes very accurately the temperature dependence of the magnetic susceptibility computed for antiferromagnetic rings of Heisenberg spins S=1 , whose size n is even and ranges from 6 to 20. This expression has been obtained through a strategy justified by scaling considerations together with finite size numerical calculations. For n large, the coefficients of the expression converge towards C1=0.125 , W1=0.451J , C2=0.564 , W2=1.793J ( J is the exchange constant), which are appropriate for describing the susceptibility of the spin-1 Haldane chain. The Curie constant, the paramagnetic Curie-Weiss temperature, the correlation length at T=0 and the Haldane gap are found to be closely related to these coefficients. With this expression, a very good description of the magnetic behavior of Y2BaNiO5 and of Ni(C2H8N2)2NO2ClO4 (NENP), the archetype of the Haldane gap systems, is achieved over the whole temperature range.

  15. Strongly correlated flat-band systems: The route from Heisenberg spins to Hubbard electrons

    NASA Astrophysics Data System (ADS)

    Derzhko, Oleg; Richter, Johannes; Maksymenko, Mykola

    2015-05-01

    On a large class of lattices (such as the sawtooth chain, the kagome and the pyrochlore lattices), the quantum Heisenberg and the repulsive Hubbard models may host a completely dispersionless (flat) energy band in the single-particle spectrum. The flat-band states can be viewed as completely localized within a finite volume (trap) of the lattice and allow for construction of many-particle states, roughly speaking, by occupying the traps with particles. If the flat-band happens to be the lowest-energy one, the manifold of such many-body states will often determine the ground-state and low-temperature physics of the models at hand even in the presence of strong interactions. The localized nature of these many-body states makes possible the mapping of this subset of eigenstates onto a corresponding classical hard-core system. As a result, the ground-state and low-temperature properties of the strongly correlated flat-band systems can be analyzed in detail using concepts and tools of classical statistical mechanics (e.g., classical lattice-gas approach or percolation approach), in contrast to more challenging quantum many-body techniques usually necessary to examine strongly correlated quantum systems. In this review, we recapitulate the basic features of the flat-band spin systems and briefly summarize earlier studies in the field. The main emphasis is made on recent developments which include results for both spin and electron flat-band models. In particular, for flat-band spin systems, we highlight field-driven phase transitions for frustrated quantum Heisenberg antiferromagnets at low temperatures, chiral flat-band states, as well as the effect of a slight dispersion of a previously strictly flat-band due to nonideal lattice geometry. For electronic systems, we discuss the universal low-temperature behavior of several flat-band Hubbard models, the emergence of ground-state ferromagnetism in the square-lattice Tasaki-Hubbard model and the related Pauli

  16. Heisenberg-Weyl Observables: Bloch vectors in phase space

    NASA Astrophysics Data System (ADS)

    Asadian, Ali; Erker, Paul; Huber, Marcus; Klöckl, Claude

    2016-07-01

    We introduce a Hermitian generalization of Pauli matrices to higher dimensions which is based on Heisenberg-Weyl operators. The complete set of Heisenberg-Weyl observables allows us to identify a real-valued Bloch vector for an arbitrary density operator in discrete phase space, with a smooth transition to infinite dimensions. Furthermore, we derive bounds on the sum of expectation values of any set of anticommuting observables. Such bounds can be used in entanglement detection and we show that Heisenberg-Weyl observables provide a first nontrivial example beyond the dichotomic case.

  17. Ground states, magnetization plateaus and bipartite entanglement of frustrated spin-1/2 Ising-Heisenberg and Heisenberg triangular tubes

    NASA Astrophysics Data System (ADS)

    Alécio, Raphael C.; Lyra, Marcelo L.; Strečka, Jozef

    2016-11-01

    The ground-state phase diagram, magnetization process and bipartite entanglement of the frustrated spin-1/2 Ising-Heisenberg and Heisenberg triangular tube (three-leg ladder) are investigated in a non-zero external magnetic field. The exact ground-state phase diagram of the spin-1/2 Ising-Heisenberg tube with Heisenberg intra-rung and Ising inter-rung couplings consists of six distinct gapped phases, which manifest themselves in a magnetization curve as intermediate plateaus at zero, one-third and two-thirds of the saturation magnetization. Four out of six available ground states exhibit quantum entanglement between two spins from the same triangular unit evidenced by a non-zero concurrence. Density-matrix renormalization group calculations are used in order to construct the ground-state phase diagram of the analogous but purely quantum spin-1/2 Heisenberg tube with Heisenberg intra- and inter-rung couplings, which consists of four gapped and three gapless phases. The Heisenberg tube shows a continuous change of the magnetization instead of a plateau at zero magnetization, while the intermediate one-third and two-thirds plateaus may be present or not in the zero-temperature magnetization curve.

  18. Archetypal-imaging and mirror-gazing.

    PubMed

    Caputo, Giovanni B

    2014-03-01

    Mirrors have been studied by cognitive psychology in order to understand self-recognition, self-identity, and self-consciousness. Moreover, the relevance of mirrors in spirituality, magic and arts may also suggest that mirrors can be symbols of unconscious contents. Carl G. Jung investigated mirrors in relation to the unconscious, particularly in Psychology and Alchemy. However, the relationship between the conscious behavior in front of a mirror and the unconscious meaning of mirrors has not been clarified. Recently, empirical research found that gazing at one's own face in the mirror for a few minutes, at a low illumination level, produces the perception of bodily dysmorphic illusions of strange-faces. Healthy observers usually describe huge distortions of their own faces, monstrous beings, prototypical faces, faces of relatives and deceased, and faces of animals. In the psychiatric population, some schizophrenics show a dramatic increase of strange-face illusions. They can also describe the perception of multiple-others that fill the mirror surface surrounding their strange-face. Schizophrenics are usually convinced that strange-face illusions are truly real and identify themselves with strange-face illusions, diversely from healthy individuals who never identify with them. On the contrary, most patients with major depression do not perceive strange-face illusions, or they perceive very faint changes of their immobile faces in the mirror, like death statues. Strange-face illusions may be the psychodynamic projection of the subject's unconscious archetypal contents into the mirror image. Therefore, strange-face illusions might provide both an ecological setting and an experimental technique for "imaging of the unconscious". Future researches have been proposed.

  19. Archetypal-imaging and mirror-gazing.

    PubMed

    Caputo, Giovanni B

    2014-03-01

    Mirrors have been studied by cognitive psychology in order to understand self-recognition, self-identity, and self-consciousness. Moreover, the relevance of mirrors in spirituality, magic and arts may also suggest that mirrors can be symbols of unconscious contents. Carl G. Jung investigated mirrors in relation to the unconscious, particularly in Psychology and Alchemy. However, the relationship between the conscious behavior in front of a mirror and the unconscious meaning of mirrors has not been clarified. Recently, empirical research found that gazing at one's own face in the mirror for a few minutes, at a low illumination level, produces the perception of bodily dysmorphic illusions of strange-faces. Healthy observers usually describe huge distortions of their own faces, monstrous beings, prototypical faces, faces of relatives and deceased, and faces of animals. In the psychiatric population, some schizophrenics show a dramatic increase of strange-face illusions. They can also describe the perception of multiple-others that fill the mirror surface surrounding their strange-face. Schizophrenics are usually convinced that strange-face illusions are truly real and identify themselves with strange-face illusions, diversely from healthy individuals who never identify with them. On the contrary, most patients with major depression do not perceive strange-face illusions, or they perceive very faint changes of their immobile faces in the mirror, like death statues. Strange-face illusions may be the psychodynamic projection of the subject's unconscious archetypal contents into the mirror image. Therefore, strange-face illusions might provide both an ecological setting and an experimental technique for "imaging of the unconscious". Future researches have been proposed. PMID:25379264

  20. Archetypal-Imaging and Mirror-Gazing

    PubMed Central

    Caputo, Giovanni B.

    2013-01-01

    Mirrors have been studied by cognitive psychology in order to understand self-recognition, self-identity, and self-consciousness. Moreover, the relevance of mirrors in spirituality, magic and arts may also suggest that mirrors can be symbols of unconscious contents. Carl G. Jung investigated mirrors in relation to the unconscious, particularly in Psychology and Alchemy. However, the relationship between the conscious behavior in front of a mirror and the unconscious meaning of mirrors has not been clarified. Recently, empirical research found that gazing at one’s own face in the mirror for a few minutes, at a low illumination level, produces the perception of bodily dysmorphic illusions of strange-faces. Healthy observers usually describe huge distortions of their own faces, monstrous beings, prototypical faces, faces of relatives and deceased, and faces of animals. In the psychiatric population, some schizophrenics show a dramatic increase of strange-face illusions. They can also describe the perception of multiple-others that fill the mirror surface surrounding their strange-face. Schizophrenics are usually convinced that strange-face illusions are truly real and identify themselves with strange-face illusions, diversely from healthy individuals who never identify with them. On the contrary, most patients with major depression do not perceive strange-face illusions, or they perceive very faint changes of their immobile faces in the mirror, like death statues. Strange-face illusions may be the psychodynamic projection of the subject’s unconscious archetypal contents into the mirror image. Therefore, strange-face illusions might provide both an ecological setting and an experimental technique for “imaging of the unconscious”. Future researches have been proposed. PMID:25379264

  1. Fourier optics from the perspective of the Heisenberg group

    NASA Astrophysics Data System (ADS)

    Raszillier, Hans; Schempp, Walter

    Introduction The quantization problem The Heisenberg group Description of the wave field Examples from quantum mechanics The phase space of geometrical optics Peculiarities of geometrical optics Phase discontinuities Systems with symmetry Summary and comments References

  2. Whittaker modules for the twisted Heisenberg-Virasoro algebra

    SciTech Connect

    Liu Dong; Wu Yuezhu; Zhu Linsheng

    2010-02-15

    We define Whittaker modules for the twisted Heisenberg-Virasoro algebra and obtain several results from the classical setting, including a classification of simple Whittaker modules by central characters.

  3. Heisenberg's Uncertainty Principle and Interpretive Research in Science Education.

    ERIC Educational Resources Information Center

    Roth, Wolff-Michael

    1993-01-01

    Heisenberg's uncertainty principle and the derivative notions of interdeterminacy, uncertainty, precision, and observer-observed interaction are discussed and their applications to social science research examined. Implications are drawn for research in science education. (PR)

  4. Primordial image and the archetypal design of art.

    PubMed

    Johnson, N B

    1991-07-01

    This paper extends Jung's work on the relationship of art to (postulated) archetypes of the collective unconscious. Archetypes of the collective unconscious, according to Jung, are revealed to ego consciousness only by way of images--images of a specific form. Jung suggests that archetypes, primordial images, combine two aspects in a single form and are therefore paradoxical. The wise old man and youth and hermaphrodites illustrate Jung's definition of a primordial image. My study of Jung's illustrations concludes that he is referring to what I term double-figures as the design form of primordial imagery. I elaborate upon the design form of double-figures, and illustrate my conception of archetypal imagery through comparative analysis of nine cases of double-figure imagery from selected prehistoric and contemporary societies. Double-figures, as archetypal primordial imagery of the collective unconscious, are spontaneously generated, autonomous, and known to a wide variety of societies. I distinguish between form and content in the study of primordial imagery, and conclude with a summary of the importance of Jung to the cross-cultural study of art.

  5. Primordial image and the archetypal design of art.

    PubMed

    Johnson, N B

    1991-07-01

    This paper extends Jung's work on the relationship of art to (postulated) archetypes of the collective unconscious. Archetypes of the collective unconscious, according to Jung, are revealed to ego consciousness only by way of images--images of a specific form. Jung suggests that archetypes, primordial images, combine two aspects in a single form and are therefore paradoxical. The wise old man and youth and hermaphrodites illustrate Jung's definition of a primordial image. My study of Jung's illustrations concludes that he is referring to what I term double-figures as the design form of primordial imagery. I elaborate upon the design form of double-figures, and illustrate my conception of archetypal imagery through comparative analysis of nine cases of double-figure imagery from selected prehistoric and contemporary societies. Double-figures, as archetypal primordial imagery of the collective unconscious, are spontaneously generated, autonomous, and known to a wide variety of societies. I distinguish between form and content in the study of primordial imagery, and conclude with a summary of the importance of Jung to the cross-cultural study of art. PMID:1938606

  6. Quasi-Linear Algebras and Integrability (the Heisenberg Picture)

    NASA Astrophysics Data System (ADS)

    Vinet, Luc; Zhedanov, Alexei

    2008-02-01

    We study Poisson and operator algebras with the ''quasi-linear property'' from the Heisenberg picture point of view. This means that there exists a set of one-parameter groups yielding an explicit expression of dynamical variables (operators) as functions of ''time'' t. We show that many algebras with nonlinear commutation relations such as the Askey-Wilson, q-Dolan-Grady and others satisfy this property. This provides one more (explicit Heisenberg evolution) interpretation of the corresponding integrable systems.

  7. Heisenberg Groups and their Automorphisms over Algebras with Central Involution

    NASA Astrophysics Data System (ADS)

    Johnson, Robert W.

    2015-08-01

    Heisenberg groups over algebras with central involution and their automorphism groups are constructed. The complex quaternion group algebra over a prime field is used as an example. Its subspaces provide finite models for each of the real and complex quadratic spaces with dimension 4 or less. A model for the representations of these Heisenberg groups and automorphism groups is constructed. A pseudo-differential operator enables a parallel treatment of spaces defined over finite and real fields.

  8. Mn4+ emission in pyrochlore oxides

    SciTech Connect

    Du, Mao-Hua

    2015-01-01

    For the existing Mn4+ activated red phosphors have relatively low emission energies (or long emission wavelengths) and are therefore inefficient for general lighting. Density functional calculations are performed to study Mn4+ emission in rare-earth hafnate, zirconate, and stannate pyrochlore oxides (RE2Hf2O7, RE2Zr2O7, and RE2Sn2O7). We show how the different sizes of the RE3+ cation in these pyrochlores affect the local structure of the distorted MnO6 octahedron, the Mn–O hybridization, and the Mn4+ emission energy. The Mn4+ emission energies of many pyrochlores are found to be higher than those currently known for Mn4+ doped oxides and should be closer to that of Y2O3:Eu3+ (the current commercial red phosphor for fluorescent lighting). The O–Mn–O bond angle distortion in a MnO6 octahedron is shown to play an important role in weakening Mn–O hybridization and consequently increasing the Mn4+ emission energy. Our result shows that searching for materials that allow significant O–Mn–O bond angle distortion in a MnO6 octahedron is an effective approach to find new Mn4+ activated red phosphors with potential to replace the relatively expensive Y2O3:Eu3+ phosphor.

  9. Archetype Development Process of Electronic Health Record of Minas Gerais.

    PubMed

    Abreu Maia, Thais; Fernandes De Muylder, Cristiana; Mendonça Queiroga, Rodrigo

    2015-01-01

    The Electronic Health Record (EHR) supports health systems and aims to reduce fragmentation, which will enable continuity of patient care. The paper's main objective is to define the steps, roles and artifacts for an archetype development process (ADP) for the EHR at the Brazilian National Health System (SUS) in the State of Minas Gerais (MG). This study was conducted using qualitative analysis based upon an applied case. It had an exploratory purpose metodologically defined in four stages: literature review; descriptive comparison; proposition of an archetype development process and proof of concept. The proof of concept showed that the proposed ADP ensures the archetype quality and supports the semantic interoperability in SUS to improve clinical safety and the continuity of patient care.

  10. Archetype, adaptation and the mammalian heart.

    PubMed

    Meijler, F L; Meijler, T D

    2011-03-01

    Forty years ago, we started our quest for 'The Holy Grail' of understanding ventricular rate control and rhythm in atrial fibrillation (AF). We therefore studied the morphology and function of a wide range of mammalian hearts. From mouse to whale, we found that all hearts show similar structural and functional characteristics. This suggests that the mammalian heart remained well conserved during evolution and in this aspect it differs from other organs and parts of the mammalian body. The archetype of the mammalian heart was apparently so successful that adaptation by natural selection (evolution) caused by varying habitat demands, as occurred in other organs and many other aspects of mammalian anatomy, bypassed the heart. The structure and function of the heart of placental mammals have thus been strikingly conserved throughout evolution. The changes in the mammalian heart that did take place were mostly adjustments (scaling), to compensate for variations in body size and shape. A remarkable scaling effect is, for instance, the difference in atrioventricular (AV) conduction time, which is vital for optimal cardiac function in all mammals, small and large. Scaling of AV conduction takes place in the AV node (AVN), but its substrate is unknown. This sheds new light on the vital role of the AVN in health and disease. The AVN is master and servant of the heart at the same time and is of salient importance for our understanding of supraventricular arrhythmias in humans, especially AF. In Information Technology a software infra-structure called 'enterprise service bus' (ESB) may provide understanding of the mammalian heart's conservation during evolution. The ESB is quite unspecific (and thus general) when compared with the specialised components it has to support. For instance, one of the functions of an ESB is the routing of messages between system nodes. This routing is independent and unaware of the content of the messages. The function of the heart is likewise

  11. Validating EHR documents: automatic schematron generation using archetypes.

    PubMed

    Pfeiffer, Klaus; Duftschmid, Georg; Rinner, Christoph

    2014-01-01

    The goal of this study was to examine whether Schematron schemas can be generated from archetypes. The openEHR Java reference API was used to transform an archetype into an object model, which was then extended with context elements. The model was processed and the constraints were transformed into corresponding Schematron assertions. A prototype of the generator for the reference model HL7 v3 CDA R2 was developed and successfully tested. Preconditions for its reusability with other reference models were set. Our results indicate that an automated generation of Schematron schemas is possible with some limitations.

  12. Interoperable Archetypes With a Three Folded Terminology Governance.

    PubMed

    Pederson, Rune; Ellingsen, Gunnar

    2015-01-01

    The use of openEHR archetypes increases the interoperability of clinical terminology, and in doing so improves upon the availability of clinical terminology for both primary and secondary purposes. Where clinical terminology is employed in the EPR system, research reports conflicting a results for the use of structuring and standardization as measurements of success. In order to elucidate this concept, this paper focuses on the effort to establish a national repository for openEHR based archetypes in Norway where clinical terminology could be included with benefit for interoperability three folded. PMID:26262236

  13. Validating EHR documents: automatic schematron generation using archetypes.

    PubMed

    Pfeiffer, Klaus; Duftschmid, Georg; Rinner, Christoph

    2014-01-01

    The goal of this study was to examine whether Schematron schemas can be generated from archetypes. The openEHR Java reference API was used to transform an archetype into an object model, which was then extended with context elements. The model was processed and the constraints were transformed into corresponding Schematron assertions. A prototype of the generator for the reference model HL7 v3 CDA R2 was developed and successfully tested. Preconditions for its reusability with other reference models were set. Our results indicate that an automated generation of Schematron schemas is possible with some limitations. PMID:24825691

  14. Nonlinear phonon interferometry at the Heisenberg limit

    NASA Astrophysics Data System (ADS)

    Cheung, Hil F. H.; Patil, Yogesh Sharad; Chang, Laura; Chakram, Srivatsan; Vengalattore, Mukund

    2016-05-01

    Interferometers operating at or close to quantum limits of precision have found wide application in tabletop searches for physics beyond the standard model, the study of fundamental forces and symmetries of nature and foundational tests of quantum mechanics. The limits imposed by quantum fluctuations and measurement backaction on conventional interferometers (δϕ 1 /√{ N}) have spurred the development of schemes to circumvent these limits through quantum interference, multiparticle interactions and entanglement. Here, we realize a prominent example of such schemes, the so-called SU(1,1) interferometer, in a fundamentally new platform in which the interfering arms are distinct flexural modes of a millimeter-scale mechanical resonator. We realize up to 15.4(3) dB of noise squeezing and demonstrate the Heisenberg scaling of interferometric sensitivity (δϕ 1 / N), corresponding to a 6-fold improvement in measurement precision over a conventional interferometer. We describe how our work extends the optomechanical toolbox and how it presents new avenues for studies of optomechanical sensing and studies of nonequilibrium dynamics of multimode optomechanical systems. This work was supported by the DARPA QuASAR program through a grant from the ARO, the ARO MURI on non-equilibrium manybody dynamics and an NSF INSPIRE award.

  15. Open timelike curves violate Heisenberg's uncertainty principle.

    PubMed

    Pienaar, J L; Ralph, T C; Myers, C R

    2013-02-01

    Toy models for quantum evolution in the presence of closed timelike curves have gained attention in the recent literature due to the strange effects they predict. The circuits that give rise to these effects appear quite abstract and contrived, as they require nontrivial interactions between the future and past that lead to infinitely recursive equations. We consider the special case in which there is no interaction inside the closed timelike curve, referred to as an open timelike curve (OTC), for which the only local effect is to increase the time elapsed by a clock carried by the system. Remarkably, circuits with access to OTCs are shown to violate Heisenberg's uncertainty principle, allowing perfect state discrimination and perfect cloning of coherent states. The model is extended to wave packets and smoothly recovers standard quantum mechanics in an appropriate physical limit. The analogy with general relativistic time dilation suggests that OTCs provide a novel alternative to existing proposals for the behavior of quantum systems under gravity.

  16. An analysis of the openehr archetype semantics based on a typed lambda theory.

    PubMed

    Tatsukawa, Akimichi; Shinohara, Emiko Y; Kawazoe, Yoshimasa; Imai, Takeshi; Ohe, Kazuhiko

    2013-01-01

    The openEHR has adopted the dual model architecture consisting of Reference Model and Archetype. The specification, however, lacks formal definitions of archetype semantics, so that its behaviors have remained ambiguous. The objective of this poster is to analyze semantics of the openEHR archetypes: its variance and mutability. We use a typed lambda calculus as an analyzing tool. As a result, we have reached the conclusion that archetypes should be 1) covariant and 2) immutable schema.

  17. An analysis of the openehr archetype semantics based on a typed lambda theory.

    PubMed

    Tatsukawa, Akimichi; Shinohara, Emiko Y; Kawazoe, Yoshimasa; Imai, Takeshi; Ohe, Kazuhiko

    2013-01-01

    The openEHR has adopted the dual model architecture consisting of Reference Model and Archetype. The specification, however, lacks formal definitions of archetype semantics, so that its behaviors have remained ambiguous. The objective of this poster is to analyze semantics of the openEHR archetypes: its variance and mutability. We use a typed lambda calculus as an analyzing tool. As a result, we have reached the conclusion that archetypes should be 1) covariant and 2) immutable schema. PMID:23920764

  18. Speciation of uranium in La2Zr2O7 pyrochlore by TRPLS

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Rajeswari, B.; Hon, N. S.; Kadam, R. M.; Natarajan, V.

    2015-06-01

    We discuss the speciation of uranium in lanthanum zirconate (La2Zr2O7 =LZO) pyrochlore ceramic prepared via a gel-combustion route. Uranium concentration in the pyrochlore was optimized to 2 mol%. XRD and SEM experiments were carried out to assess the phase and homogeneity of the prepared samples. Time resolved photoluminescence (TRPLS) investigations were carried out for understanding the species stabilized in the pyrochlore host. It was observed that, uranium exists as uranate ion (UO66-) in the zirconate host where it replaces the `Zr' ions at its regular site with surrounding defect centers created for charge compensation.

  19. Pulsed laser deposition and characterizations of pyrochlore iridate thin films

    NASA Astrophysics Data System (ADS)

    Starr, Matthew; Aviles-Acosta, Jaime; Xie, Yuantao; Zhu, Wenka; Li, Zhen; Chen, Aiping; Li, Nan; Tao, Chenggang; Jia, Quanxi; Heremans, J. J.; Zhang, S. X.

    Pyrochlore iridates have attracted growing interest in recent years because of their potential to realize novel topological phases. While most of the previous studies have focused on polycrystalline and single crystalline bulk samples, epitaxial thin films offer a unique platform for controllable tuning of material parameters such as oxygen stoichiometry and elastic strain to achieve new electronic states. In this talk, we will present the growth and characterizations of epitaxial thin films of pyrochlore Y2Ir2O7 and Bi2Ir2O7 that are predicted to host topologically non-trivial states. The iridate thin films were grown by pulsed laser deposition at different conditions, and a narrow window for epitaxial growth was determined. Characterizations of crystalline structures were performed using X-ray diffraction and transmission electron microscopy to establish a growth parameter-structure phase diagram. The compositions of thin films were determined by energy dispersive X-ray spectroscopy, and the surface morphologies were characterized using atomic force microscopy and scanning tunneling microscopy. Magneto-transport studies indicate a strong dependence of transport properties on the oxygen stoichiometry and the film thickness.

  20. Thin film growth using hetero embryo: demonstration on pyrochlore phase.

    PubMed

    Pillonnet, A; Le Bihan, V; Masenelli, B; Ledoux, G; Marty, O; Mélinon, P; Dujardin, C

    2010-05-01

    The paper reports the possible use of nanoparticles embedded in amorphous host as hetero embryos in order to grow complex crystalline phases as thin film. Demonstration is performed in the prototypical case of pyrochlore phase Gd(2)Ti(2)O(7) grown from Gd(2)O(3) nanoparticles embedded in TiO(2) matrix at low temperature. As embryos, two kinds of nanoparticles are compared: clusters deposited by low energy cluster beam deposition (LECBD) and nanostructured films elaborated by sol-gel process. The growth has been analyzed by X-ray diffraction and transmission electron microscopy. Furthermore, the nanoparticles have been doped with Eu(3+) luminescence probes in order to follow the nucleation mechanisms at the atomic scale. It is shown that the size, shape, and composition of hetero embryos and as well their interfaces are of paramount importance to enhance the formation of complex materials, such as pyrochlore. By this mean, the first step in classical nucleation science, controlling the height of the energetic barrier, is skipped and the synthesis conditions can be eased.

  1. Microscopic Origin of Heisenberg and Non-Heisenberg Exchange Interactions in Ferromagnetic bcc Fe.

    PubMed

    Kvashnin, Y O; Cardias, R; Szilva, A; Di Marco, I; Katsnelson, M I; Lichtenstein, A I; Nordström, L; Klautau, A B; Eriksson, O

    2016-05-27

    By means of first principles calculations, we investigate the nature of exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the basic electronic structure reveals a drastic difference between the 3d orbitals of E_{g} and T_{2g} symmetries. The latter ones define the shape of the Fermi surface, while the former ones form weakly interacting impurity levels. We demonstrate that, as a result of this, in Fe the T_{2g} orbitals participate in exchange interactions, which are only weakly dependent on the configuration of the spin moments and thus can be classified as Heisenberg-like. These couplings are shown to be driven by Fermi surface nesting. In contrast, for the E_{g} states, the Heisenberg picture breaks down since the corresponding contribution to the exchange interactions is shown to strongly depend on the reference state they are extracted from. Our analysis of the nearest-neighbor coupling indicates that the interactions among E_{g} states are mainly proportional to the corresponding hopping integral and thus can be attributed to be of double-exchange origin. By making a comparison to other magnetic transition metals, we put the results of bcc Fe into context and argue that iron has a unique behavior when it comes to magnetic exchange interactions. PMID:27284671

  2. Microscopic Origin of Heisenberg and Non-Heisenberg Exchange Interactions in Ferromagnetic bcc Fe

    NASA Astrophysics Data System (ADS)

    Kvashnin, Y. O.; Cardias, R.; Szilva, A.; Di Marco, I.; Katsnelson, M. I.; Lichtenstein, A. I.; Nordström, L.; Klautau, A. B.; Eriksson, O.

    2016-05-01

    By means of first principles calculations, we investigate the nature of exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the basic electronic structure reveals a drastic difference between the 3 d orbitals of Eg and T2 g symmetries. The latter ones define the shape of the Fermi surface, while the former ones form weakly interacting impurity levels. We demonstrate that, as a result of this, in Fe the T2 g orbitals participate in exchange interactions, which are only weakly dependent on the configuration of the spin moments and thus can be classified as Heisenberg-like. These couplings are shown to be driven by Fermi surface nesting. In contrast, for the Eg states, the Heisenberg picture breaks down since the corresponding contribution to the exchange interactions is shown to strongly depend on the reference state they are extracted from. Our analysis of the nearest-neighbor coupling indicates that the interactions among Eg states are mainly proportional to the corresponding hopping integral and thus can be attributed to be of double-exchange origin. By making a comparison to other magnetic transition metals, we put the results of bcc Fe into context and argue that iron has a unique behavior when it comes to magnetic exchange interactions.

  3. A Curriculum Framework Based on Archetypal Phenomena and Technologies.

    ERIC Educational Resources Information Center

    Zubrowski, Bernie

    2002-01-01

    Presents an alternative paradigm of curriculum development based on the theory of situated cognition. This approach starts with context rather than concept, gives greater weight to students' interpretative frameworks, and provides for a more holistic development. Presents a grade 1-8 framework that uses archetypal phenomena and technologies as the…

  4. The image schema and innate archetypes: theoretical and clinical implications.

    PubMed

    Merchant, John

    2016-02-01

    Based in contemporary neuroscience, Jean Knox's 2004 JAP paper 'From archetypes to reflective function' honed her position on image schemas, thereby introducing a model for archetypes which sees them as 'reliably repeated early developmental achievements' and not as genetically inherited, innate psychic structures. The image schema model is used to illustrate how the analyst worked with a patient who began life as an unwanted pregnancy, was adopted at birth and as an adult experienced profound synchronicities, paranormal/telepathic phenomena and visions. The classical approach to such phenomena would see the intense affectivity arising out of a ruptured symbiotic mother-infant relationship constellating certain archetypes which set up the patient's visions. This view is contrasted with Knox's model which sees the archetype an sich as a developmentally produced image schema underpinning the emergence of later imagery. The patient's visions can then be understood to arise from his psychoid body memory related to his traumatic conception and birth. The contemporary neuroscience which supports this view is outlined and a subsequent image schema explanation is presented. Clinically, the case material suggests that a pre-birth perspective needs to be explored in all analytic work. Other implications of Knox's image schema model are summarized. PMID:26785413

  5. The mutating preconscious archetype in present-day ecological conditions.

    PubMed

    Włoch, K

    1990-12-01

    Competition is an important force behind evolution in present-day ecological conditions, its intensity varying according to the organisms' expectations vis-à-vis resources available. On the other hand, the role of mutation in the evolutionary process can hardly be underestimated: Leading to the change of the preconsciously functioning archetype, mutation makes it impossible for the ego to realize its image. This is a consequence of the clash between the mutated, preconsciously functioning archetype and the system of ethical and moral norms functioning in the collective superego of a given population group. The type of mutation that results from the accelerated pace of evolution can be viewed as a continuity in the development of an organism's behavior. The preconsciously functioning archetype, resulting from these mutations, contains impulses and predispositions that differ markedly from the impulses and predispositions functioning in the genetically determined "pattern of behavior." In a situation where anxiety results from the inhibition of impulses and dispositions, hostility reactions are likely to occur. In its turn, reactive hostility can induce anxiety, thus creating a reaction cycle. Underlying this mechanism is the mutated, preconsciously functioning archetype, which itself is a result of the development of civilization in our contemporary world.

  6. Archetypal Theory and Women's Fiction: 1688-1975.

    ERIC Educational Resources Information Center

    Pratt, Annis

    The purpose of this paper is to trace a descriptive history of woman's psyche as manifested in English and American literature by and about women during the period from 1688 through 1975. The application of archetypal theory (the description of recurrent patterns in symbolic and narrative structures within a wide and complex field of material) to…

  7. The image schema and innate archetypes: theoretical and clinical implications.

    PubMed

    Merchant, John

    2016-02-01

    Based in contemporary neuroscience, Jean Knox's 2004 JAP paper 'From archetypes to reflective function' honed her position on image schemas, thereby introducing a model for archetypes which sees them as 'reliably repeated early developmental achievements' and not as genetically inherited, innate psychic structures. The image schema model is used to illustrate how the analyst worked with a patient who began life as an unwanted pregnancy, was adopted at birth and as an adult experienced profound synchronicities, paranormal/telepathic phenomena and visions. The classical approach to such phenomena would see the intense affectivity arising out of a ruptured symbiotic mother-infant relationship constellating certain archetypes which set up the patient's visions. This view is contrasted with Knox's model which sees the archetype an sich as a developmentally produced image schema underpinning the emergence of later imagery. The patient's visions can then be understood to arise from his psychoid body memory related to his traumatic conception and birth. The contemporary neuroscience which supports this view is outlined and a subsequent image schema explanation is presented. Clinically, the case material suggests that a pre-birth perspective needs to be explored in all analytic work. Other implications of Knox's image schema model are summarized.

  8. [Archetypal aspects of aging: from Eros to Thanatos].

    PubMed

    Pérez Urdániz, A; Bueno Carrera, G; Santos García, J M; Molina Ramos, R; Rubio Larrosa, V

    1999-01-01

    From a Junguian point of view, the different archetypal roles of the aging process, along the life cycle, are studied: eros, puer, logos, hero, persona, mascara, anima, animus, king, warrior, magician, lover, mother, virgin, afrodite, witch, self, senex, shadow, tanatos. PMID:10380154

  9. Archetype Model-Driven Development Framework for EHR Web System

    PubMed Central

    Kimura, Eizen; Ishihara, Ken

    2013-01-01

    Objectives This article describes the Web application framework for Electronic Health Records (EHRs) we have developed to reduce construction costs for EHR sytems. Methods The openEHR project has developed clinical model driven architecture for future-proof interoperable EHR systems. This project provides the specifications to standardize clinical domain model implementations, upon which the ISO/CEN 13606 standards are based. The reference implementation has been formally described in Eiffel. Moreover C# and Java implementations have been developed as reference. While scripting languages had been more popular because of their higher efficiency and faster development in recent years, they had not been involved in the openEHR implementations. From 2007, we have used the Ruby language and Ruby on Rails (RoR) as an agile development platform to implement EHR systems, which is in conformity with the openEHR specifications. Results We implemented almost all of the specifications, the Archetype Definition Language parser, and RoR scaffold generator from archetype. Although some problems have emerged, most of them have been resolved. Conclusions We have provided an agile EHR Web framework, which can build up Web systems from archetype models using RoR. The feasibility of the archetype model to provide semantic interoperability of EHRs has been demonstrated and we have verified that that it is suitable for the construction of EHR systems. PMID:24523991

  10. Archetypal Narratives in Career Counselling: A Chaos Theory Application

    ERIC Educational Resources Information Center

    Pryor, Robert G. L.; Bright, Jim E. H.

    2008-01-01

    This paper seeks to extend previous work on narrative career counselling by considering the role of plot within clients' narratives. Seven archetypal narratives derived from the work of Booker (2004) are introduced that represent systems of meaning to provide insight into how individuals interpret their experience. These plots can be understood…

  11. Sustainable clinical knowledge management: an archetype development life cycle.

    PubMed

    Madsen, Maria; Leslie, Heather; Hovenga, Evelyn J S; Heard, Sam

    2010-01-01

    This chapter gives an educational overview of: 1. The significance of having a formal ontology of health care data 2. How openEHR has used an ontological approach to designing an electronic health record 3. The phases of archetype development and key steps in the process 4. The openEHR architecture and integrated development environment.

  12. Opposite correlations between cation disordering and amorphization resistance in spinels versus pyrochlores

    SciTech Connect

    Uberuaga, Blas Pedro; Tang, Ming; Jiang, Chao; Valdez, James A.; Smith, Roger; Wang, Yongqiang; Sickafus, Kurt E.

    2015-10-29

    Understanding and predicting radiation damage evolution in complex materials is crucial for developing next-generation nuclear energy sources. Here, using a combination of ion beam irradiation, transmission electron microscopy and X-ray diffraction, we show that, contrary to the behaviour observed in pyrochlores, the amorphization resistance of spinel compounds correlates directly with the energy to disorder the structure. Using a combination of atomistic simulation techniques, we ascribe this behaviour to structural defects on the cation sublattice that are present in spinel but not in pyrochlore. Specifically, because of these structural defects, there are kinetic pathways for the relaxation of disorder in spinel that are absent in pyrochlore. This leads to a direct correlation between amorphization resistance and disordering energetics in spinel, the opposite of that observed in pyrochlores. Furthermore, these results provide new insight into the origins of amorphization resistance in complex oxides beyond fluorite derivatives.

  13. Opposite correlations between cation disordering and amorphization resistance in spinels versus pyrochlores

    PubMed Central

    Uberuaga, Blas Pedro; Tang, Ming; Jiang, Chao; Valdez, James A.; Smith, Roger; Wang, Yongqiang; Sickafus, Kurt E.

    2015-01-01

    Understanding and predicting radiation damage evolution in complex materials is crucial for developing next-generation nuclear energy sources. Here, using a combination of ion beam irradiation, transmission electron microscopy and X-ray diffraction, we show that, contrary to the behaviour observed in pyrochlores, the amorphization resistance of spinel compounds correlates directly with the energy to disorder the structure. Using a combination of atomistic simulation techniques, we ascribe this behaviour to structural defects on the cation sublattice that are present in spinel but not in pyrochlore. Specifically, because of these structural defects, there are kinetic pathways for the relaxation of disorder in spinel that are absent in pyrochlore. This leads to a direct correlation between amorphization resistance and disordering energetics in spinel, the opposite of that observed in pyrochlores. These results provide new insight into the origins of amorphization resistance in complex oxides beyond fluorite derivatives. PMID:26510750

  14. Opposite correlations between cation disordering and amorphization resistance in spinels versus pyrochlores

    DOE PAGESBeta

    Uberuaga, Blas Pedro; Tang, Ming; Jiang, Chao; Valdez, James A.; Smith, Roger; Wang, Yongqiang; Sickafus, Kurt E.

    2015-10-29

    Understanding and predicting radiation damage evolution in complex materials is crucial for developing next-generation nuclear energy sources. Here, using a combination of ion beam irradiation, transmission electron microscopy and X-ray diffraction, we show that, contrary to the behaviour observed in pyrochlores, the amorphization resistance of spinel compounds correlates directly with the energy to disorder the structure. Using a combination of atomistic simulation techniques, we ascribe this behaviour to structural defects on the cation sublattice that are present in spinel but not in pyrochlore. Specifically, because of these structural defects, there are kinetic pathways for the relaxation of disorder in spinelmore » that are absent in pyrochlore. This leads to a direct correlation between amorphization resistance and disordering energetics in spinel, the opposite of that observed in pyrochlores. Furthermore, these results provide new insight into the origins of amorphization resistance in complex oxides beyond fluorite derivatives.« less

  15. Atomic disorder in Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore

    SciTech Connect

    Zhang, F. X.; Lang, M.; Ewing, R. C.

    2015-05-11

    Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore with different degrees of cation disorder were synthesized by isothermal annealing at various temperatures (1100–1550 °C), and the related changes in the structure were investigated by ambient and high pressure x-ray diffraction (XRD) measurements. Unit cell parameters increase almost linearly with increasing treatment temperature. The degree of cation order in pyrochlore also increases with the increase of temperature, but saturates at ∼60%. The compressibility of the pyrochlore structures decreases when the degree of cation order increases. High pressure XRD measurements also indicate that the phase stability of Gd{sub 2}Zr{sub 2}O{sub 7} is not very sensitive to the degree of atomic disorder in the pyrochlore structure.

  16. Optimization of pyrochlore catalysts for the dry reforming of methane

    NASA Astrophysics Data System (ADS)

    Polo Garzon, Felipe

    The conversion of methane into syngas (a mixture of CO and H2), which can be further converted into a variety of chemicals and particularly liquid fuels, is of growing importance given recent increases in methane production world-wide. Furthermore, since using CO2 as the co-feed offers many environmental advantages, dry reforming of methane (DRM, CH4 + CO2 [special character omitted] 2CO + 2H 2) has received renewed attention. In recent years, experimentalists have shown that the Rh-substituted lanthanum zirconate pyrochlore (LRhZ) material is catalytically active for DRM, exhibits long-term thermal stability and resists deactivation; however, previous to this doctoral work, a detailed understanding of the reaction mechanism on pyrochlore catalyst surfaces was still scarce, making it difficult to optimize this material. In this work, initial computational efforts employing density functional theory (DFT) showed the plane (111) of the LRhZ crystal structure as the one catalytically active for DRM. In addition, the primary reaction pathway was identified, along with two rate determining steps (RDSs), the CH2 oxygenation step and the CHO dehydrogenation step, which lie on the CH 4 dehydrogenation/oxygenation path. The mechanistic understanding of DRM over LRhZ was further developed using steady-state isotopic transient kinetic analysis (SSITKA). Reversible adsorption of CO2 on the surface was observed, along with short surface residence times (< 0.6 s) at 650 and 800 °C, and increasing turnover frequencies with temperature. Comparisons between isotopic responses supported the DFT-derived reaction mechanism. Furthermore, isotopic transient kinetics confirmed that all metal atoms (Rh, Zr and La) on the surface are involved in the reaction mechanism, as previously pointed by DFT calculations. A DFT-based microkinetic model that predicts the reaction performance at different conditions was built. The model was validated against experimental data, showing remarkable

  17. Approaching the Heisenberg Limit Without Single-Particle Detection

    NASA Astrophysics Data System (ADS)

    Bentsen, Gregory; Davis, Emily; Schleier-Smith, Monika

    2016-05-01

    Achieving Heisenberg-limited measurements with ensembles of more than a few particles remains a major outstanding challenge. The problem is two-fold: one must not only prepare a sufficiently sensitive state, but also be able to detect it. While it is commonly assumed that Heisenberg-limited measurement demands single-particle-resolved detection, we propose an alternative approach that bypasses this requirement. We show that the ``one-axis twisting'' interaction, well known for generating spin squeezing in atomic ensembles, can also amplify the output signal of an entanglement-enhanced interferometer to facilitate readout. Even in the presence of dissipation, the protocol significantly relaxes the detection resolution required for spectroscopy beyond the standard quantum limit, and achieves near-Heisenberg-limited precision in a √{ N}-times shorter evolution than is required to reach the GHZ state. AFOSR, NSF.

  18. Thermodynamic stability of actinide pyrochlore minerals in deep geologic repository environments

    SciTech Connect

    WANG,YIFENG; XU,HUIFANG

    2000-03-14

    Crystalline phases of pyrochlore (e.g., CaPuTi{sub 2}O{sub 7}, CaUTi{sub 2}O{sub 7}) have been proposed as a durable ceramic waste form for disposal of high level radioactive wastes including surplus weapons-usable plutonium. In this paper, the authors use a linear free energy relationship to predict the Gibbs free energies of formation of pyrochlore phases (CaMTi{sub 2}O{sub 7}). The Pu-pyrochlore phase is predicted to be stable with respect to PuO{sub 2}, CaTiO{sub 3}, and TiO{sub 2} at room temperatures. Pu-pyrochlore is expected to be stable in a geologic repository where silica and carbonate components are absent or limited. The authors suggest that a repository in a salt formation be an ideal environment for disposal of high level, pyrochlore-based ceramic wastes. In such environment, adding CaO as a backfill will make pyrochlore minerals thermodynamically stable and therefore effectively prevent actinide release from these mineral phases.

  19. Natural occurrence and stability of pyrochlore in carbonatites, related hydrothermal systems, and weathering environments

    SciTech Connect

    Lumpkin, G.R.; Mariano, A.N.

    1996-08-01

    Stoichiometric and non-stoichiometric (defect) pyrochlores crystallize during the magmatic and late magmatic-hydrothermal phases of carbonatite emplacement (T > 450--550 C, P < 2 kb). Defect pyrochlores can also form at low temperatures in laterite horizons during weathering. After crystallization, pyrochlore is subject to alteration by hydrothermal fluids (T {approximately} 550--200 C) and ground water. Alteration occurs primarily by ion exchange of low valence A-site cations together with O, F, and OH ions. The high valence cations Th and U are generally immobile; however, the authors have documented one example of hydrothermal alteration involving loss of U together with cation exchange at the B-site in samples from Mountain Pass, California. During laterite accumulation, the cation exchange rate of pyrochlore greatly exceeds the rate of matrix dissolution. The exceptional durability of pyrochlore in natural environments is related to the stability of the B-site framework cations. In carbonatites, defect pyrochlores may contain significant amounts of Si (up to 7.6 wt% SiO{sub 2}) which is negatively correlated with Nb.

  20. Integrable higher order deformations of Heisenberg supermagnetic model

    SciTech Connect

    Guo Jiafeng; Yan Zhaowen; Wang Shikun; Wu Ke; Zhao Weizhong

    2009-11-15

    The Heisenberg supermagnet model is an integrable supersymmetric system and has a close relationship with the strong electron correlated Hubbard model. In this paper, we investigate the integrable higher order deformations of Heisenberg supermagnet models with two different constraints: (i) S{sup 2}=3S-2I for S is an element of USPL(2/1)/S(U(2)xU(1)) and (ii) S{sup 2}=S for S is an element of USPL(2/1)/S(L(1/1)xU(1)). In terms of the gauge transformation, their corresponding gauge equivalent counterparts are derived.

  1. Lipschitz control of geodesics in the Heisenberg group.

    SciTech Connect

    Berry, Robert Dan

    2010-12-01

    Monge first posed his (L{sup 1}) optimal mass transfer problem: to find a mapping of one distribution into another, minimizing total distance of transporting mass, in 1781. It remained unsolved in R{sup n} until the late 1990's. This result has since been extended to Riemannian manifolds. In both cases, optimal mass transfer relies upon a key lemma providing a Lipschitz control on the directions of geodesics. We will discuss the Lipschitz control of geodesics in the (subRiemannian) Heisenberg group. This provides an important step towards a potential theoretic proof of Monge's problem in the Heisenberg group.

  2. Gapless chiral spin liquid in a kagome Heisenberg model

    NASA Astrophysics Data System (ADS)

    Bieri, Samuel; Messio, Laura; Bernu, Bernard; Lhuillier, Claire

    2015-08-01

    Motivated by recent experiments on the Heisenberg S =1 /2 quantum spin liquid candidate material kapellasite, we classify all possible chiral (time-reversal symmetry breaking) spin liquids with fermionic spinons on the kagome lattice. We obtain the phase diagram for the physically relevant extended Heisenberg model, comparing the energies of a wide range of microscopic variational wave functions. We propose that, at low temperature, kapellasite exhibits a gapless chiral spin liquid phase with spinon Fermi surfaces. This two-dimensional state inherits many properties of the nearby one-dimensional phase of decoupled antiferromagnetic spin chains, but also shows some remarkable differences. We discuss the spin structure factors and other physical properties.

  3. The topological basis expression of Heisenberg spin chain

    NASA Astrophysics Data System (ADS)

    Hu, Taotao; Ren, Hang; Xue, Kang

    2013-11-01

    In this paper, it is shown that the Heisenberg XY, XXZ, XXX, and Ising model all can be constructed from the Braid group algebra generator and the Temperley-Lieb algebra generator. And a new set of topological basis expression is presented. Through acting on the different subspaces, we get the new nontrivial six-dimensional and four-dimensional Braid group matrix representations and Temperley-Lieb matrix representations. The eigenstates of Heisenberg model can be described by the combination of the set of topological bases. It is worth mentioning that the ground state is closely related to parameter q which is the meaningful topological parameter.

  4. Heisenberg-scaled magnetometer with dipolar spin-1 condensates

    NASA Astrophysics Data System (ADS)

    Xing, Haijun; Wang, Anbang; Tan, Qing-Shou; Zhang, Wenxian; Yi, Su

    2016-04-01

    We propose a scheme to realize a Heisenberg-scaled magnetometer using dipolar spin-1 condensates. The input state of magnetometer is prepared by slowly sweeping a transverse magnetic field to zero, which yields a highly entangled spin state of N atoms. We show that this process is protected by a parity symmetry such that the state preparation time is within the reach of the current experiment. We also propose a parity measurement with a Stern-Gerlach apparatus which is shown to approach the optimal measurement in the large atom number limit. Finally, we show that the phase estimation sensitivity of the proposed scheme roughly follows the Heisenberg scaling.

  5. Methane oxidative coupling over nonstoichiometric bismuth -tin pyrochlore catalysts

    SciTech Connect

    Mims, C.A.; Hall, R.B.; Lewandowski, J.T.

    1995-05-01

    A series of expanded pyrochlore oxides Bi{sub 2}Sn{sub 2{minus}x}Bi{sub x}O{sub 7{minus}x/2} (O{le} x {le} 0.86) was synthesized and the influence of their composition on their performance as methane coupling catalysts was examined. A trend to higher selectivity and lower activity accompanies increases in x. However, analysis of the kinetic data by a simple procedure which separates the catalyst activity and selectivity shows that all the catalysts have similar intrinsic surface selectivities, independent of composition. The trend in observed selectivity is an indirect effect of variations in activity. The similarity in surface selectivity is attributed to the formation of a bismuth-oxide-rich surface layer in all materials upon heating to reaction temperatures. 47 refs., 10 figs., 1 tab.

  6. Displacive disorder in three high-k bismuth oxide pyrochlores

    SciTech Connect

    Melot, B.; Rodriguez, E.; Proffen, Th.; Hayward, M.A.; Seshadri, R. . E-mail: seshadri@mrl.ucsb.edu

    2006-05-25

    We use time-of-flight neutron powder diffraction to examine static displacive disorder in three different pyrochlore A{sub 2}B{sub 2}O{sub 6}O' compounds with Bi on the A site. The compounds (Bi{sub 1.5}Zn{sub 0.5})(Nb{sub 1.5}Zn{sub 0.5})O{sub 6}O' (BZN) (Bi{sub 1.5}Zn{sub 0.5})(Ta{sub 1.5}Zn{sub 0.5})O{sub 6}O' (BZT), and (Bi{sub 1.5}Zn{sub 0.5})(Sb{sub 1.5}Zn{sub 0.5})O{sub 6}O' (BZS), are of interest - particularly BZN - for their high dielectric constants in the absence of any phase transition from the cubic high temperature phase. The local structures of the three compounds is characterized by displacive disorder from the ideal pyrochlore positions for both the A and O' sites, with the precise nature of the disorder being quite similar. However the extent of displacive disorder is different, despite the B-O networks being nearly identical in the three compounds. The reported dielectric constants of the three compounds are related to the extent of local displacement, and BZN, with the largest extent of local atomic displacement of A and O', is also reported to have the largest dielectric constant at 1 MHz. The dielectric constants are also related to the magnitudes of the thermal parameters of the different ions. The strongest correlation is found to involve the thermal parameter on the B site (Nb, Ta, or Sb)

  7. The archetypal senex: an exploration of old age.

    PubMed

    Hubback, J

    1996-01-01

    This paper contains three sections. The first consists of a circumambulation of some of the themes suggested by Jung's work on the last of the developmental archetypes, offering examples of descriptions culled from poetry and from contemporary Jungian writers. The second section goes into more detail about Jung himself in old age, the senex archetype and its connection with the child and the puer. It deals with losses in old age, and responses and reactions to them: wise acceptance, the stimulation of late creativity, and fury at the frustration of still remaining potentials. The paper attempts to warn against the idealization when someone in the senex stage of life is seen as only the wise old person, and argues for the healthy side of the energetic assertions frequently manifested in the late years of life, which are similar to those of infants and small children. Clinical material is included.

  8. The archetypal senex: an exploration of old age.

    PubMed

    Hubback, J

    1996-01-01

    This paper contains three sections. The first consists of a circumambulation of some of the themes suggested by Jung's work on the last of the developmental archetypes, offering examples of descriptions culled from poetry and from contemporary Jungian writers. The second section goes into more detail about Jung himself in old age, the senex archetype and its connection with the child and the puer. It deals with losses in old age, and responses and reactions to them: wise acceptance, the stimulation of late creativity, and fury at the frustration of still remaining potentials. The paper attempts to warn against the idealization when someone in the senex stage of life is seen as only the wise old person, and argues for the healthy side of the energetic assertions frequently manifested in the late years of life, which are similar to those of infants and small children. Clinical material is included. PMID:8851253

  9. Are archetypes transmitted or emergent? A response to Christian Roesler.

    PubMed

    Martin-Vallas, François

    2013-04-01

    In this paper the author argues that Jung's concept of archetype should not be reduced to an univocal definition. Jung himself proposed many definitions of this concept, some of them being partially or totally contradictory to others. A univocal and logical way of thinking can lead us to refute and reject part of those definitions, but a complex way of thinking, as proposed by Edgar Morin or Roy Bhaskar for example, can allow us to consider that those apparent contradictions in Jung's definitions of archetype reflect the complexity of the psychic reality. The main argument of the author is that Jung was missing the epistemological concept of emergence (which appeared in science at the time of his death) and that he tried to express it with the epistemological concepts of his time. PMID:23550577

  10. Using archetypes to design services for high users of healthcare.

    PubMed

    Vaillancourt, Samuel; Shahin, Ilan; Aggarwal, Payal; Pomedli, Steve; Hayden, Leigh; Pus, Laura; Bhattacharyya, Onil

    2014-01-01

    A subset of people with complex health and social needs account for the majority of healthcare costs in Ontario. There is broad agreement that better solutions for these patients could lead to better health outcomes and lower costs, but we have few tools to design services around their diverse needs. Predictive modelling may help determine numbers of high users, but design methods such as user archetypes may offer important ways of understanding how to meet their needs. We studied a range of patient profiles and interviews with frequent emergency department users to develop four archetypes of patients with complex needs to orient the service design process. These can be refined and adapted for use within initiatives like Health Links to help provide more appropriate cost-effective care. PMID:25880862

  11. Are archetypes transmitted or emergent? A response to Christian Roesler.

    PubMed

    Martin-Vallas, François

    2013-04-01

    In this paper the author argues that Jung's concept of archetype should not be reduced to an univocal definition. Jung himself proposed many definitions of this concept, some of them being partially or totally contradictory to others. A univocal and logical way of thinking can lead us to refute and reject part of those definitions, but a complex way of thinking, as proposed by Edgar Morin or Roy Bhaskar for example, can allow us to consider that those apparent contradictions in Jung's definitions of archetype reflect the complexity of the psychic reality. The main argument of the author is that Jung was missing the epistemological concept of emergence (which appeared in science at the time of his death) and that he tried to express it with the epistemological concepts of his time.

  12. Biogeochemical and Hydrological Heterogeneity and Emergent Archetypical Catchment Response Patterns

    NASA Astrophysics Data System (ADS)

    Jawitz, J. W.; Gall, H. E.; Rao, P. S.

    2014-12-01

    What can stream hydrologic and biogeochemical signals tell us about interactions among spatially heterogeneous hydrological and biogeochemical processes at the catchment-scale? We seek to understand how the spatial structure of solute sources coupled with both stationary and nonstationary hydroclimatic drivers affect observed archetypes of concentration-discharge (C-Q) patterns. These response patterns are the spatially integrated expressions of the spatiotemporal structure of solutes exported from managed catchments, and can provide insight into likely ecological consequences of receiving water bodies (e.g., wetlands, rivers, lakes, and coastal waters). We investigated the following broad questions: (1) How does the spatial correlation between the structure of flow-generating areas and biogeochemical source areas across a catchment evolve under stochastic hydro-climatic forcing? (2) What are the feasible hydrologic and biogeochemical responses that lead to the emergence of archetypical C-Q patterns? and; (3) What implications do these coupled dynamics have for catchment monitoring and implementation of management practices? We categorize the observed temporal signals into three archetypical C-Q patterns: dilution; accretion, and constant concentration. We applied a parsimonious stochastic model of heterogeneous catchments, which act as hydrologic and biogeochemical filters, to examine the relationship between spatial heterogeneity and temporal history of solute export signals. The core concept of the modeling framework is considering the type and degree of spatial correlation between solute source zones and flow generating zones, and activation of different portions of the catchments during rainfall events. Our overarching hypothesis is that each archetype C-Q pattern can be generated by explicitly linking landscape-scale hydrologic responses and spatial distributions of solute source properties within a catchment. We compared observed multidecadal data to

  13. Systoles on Heisenberg groups with Carnot-Caratheodory metrics

    SciTech Connect

    Dontsov, V V

    2001-04-30

    The systolic properties of the nilmanifolds N{sup 2n+1} associated with the higher Heisenberg groups H{sub 2n+1} are studied. Effective estimates of the systolic constants {sigma}(N{sup 2n+1}) in the Carnot-Caratheodory geometry, as functions of the parameters defining a uniform lattice on H{sub 2n+1}, are obtained.

  14. Thermodynamics of the Heisenberg ferromagnet in an applied magnetic field.

    NASA Technical Reports Server (NTRS)

    Flax, L.

    1972-01-01

    The anisotropic-Heisenberg-ferromagnet formalism developed previously is examined to include an applied magnetic field for the isotropic case in the random-phase approximation. Thermodynamic quantities such as magnetization, susceptibility, and the derivative of magnetization with respect to temperature are studied near the Curie point.

  15. Identifying behaviour patterns of construction safety using system archetypes.

    PubMed

    Guo, Brian H W; Yiu, Tak Wing; González, Vicente A

    2015-07-01

    Construction safety management involves complex issues (e.g., different trades, multi-organizational project structure, constantly changing work environment, and transient workforce). Systems thinking is widely considered as an effective approach to understanding and managing the complexity. This paper aims to better understand dynamic complexity of construction safety management by exploring archetypes of construction safety. To achieve this, this paper adopted the ground theory method (GTM) and 22 interviews were conducted with participants in various positions (government safety inspector, client, health and safety manager, safety consultant, safety auditor, and safety researcher). Eight archetypes were emerged from the collected data: (1) safety regulations, (2) incentive programs, (3) procurement and safety, (4) safety management in small businesses (5) production and safety, (6) workers' conflicting goals, (7) blame on workers, and (8) reactive and proactive learning. These archetypes capture the interactions between a wide range of factors within various hierarchical levels and subsystems. As a free-standing tool, they advance the understanding of dynamic complexity of construction safety management and provide systemic insights into dealing with the complexity. They also can facilitate system dynamics modelling of construction safety process.

  16. Identifying behaviour patterns of construction safety using system archetypes.

    PubMed

    Guo, Brian H W; Yiu, Tak Wing; González, Vicente A

    2015-07-01

    Construction safety management involves complex issues (e.g., different trades, multi-organizational project structure, constantly changing work environment, and transient workforce). Systems thinking is widely considered as an effective approach to understanding and managing the complexity. This paper aims to better understand dynamic complexity of construction safety management by exploring archetypes of construction safety. To achieve this, this paper adopted the ground theory method (GTM) and 22 interviews were conducted with participants in various positions (government safety inspector, client, health and safety manager, safety consultant, safety auditor, and safety researcher). Eight archetypes were emerged from the collected data: (1) safety regulations, (2) incentive programs, (3) procurement and safety, (4) safety management in small businesses (5) production and safety, (6) workers' conflicting goals, (7) blame on workers, and (8) reactive and proactive learning. These archetypes capture the interactions between a wide range of factors within various hierarchical levels and subsystems. As a free-standing tool, they advance the understanding of dynamic complexity of construction safety management and provide systemic insights into dealing with the complexity. They also can facilitate system dynamics modelling of construction safety process. PMID:25909389

  17. Synthesis, characterization, and catalytic activity of Rh-based lanthanum zirconate pyrochlores for higher alcohol synthesis

    SciTech Connect

    Abdelsayed, Victor; Shekhawat, Dushyant; Poston, James A; Spivey, James J

    2013-05-01

    Two lanthanum zirconate pyrochlores (La{sub 2}Zr{sub 2}O{sub 7}; LZ) were prepared by Pechini method and tested for higher alcohols selectivity. In one, Rh was substituted into the pyrochlore lattice (LRZ, 1.7 wt%) while for the second, Rh was supported on an unsubstituted La{sub 2}Zr{sub 2}O{sub 7} (R/LZ, 1.8 wt%). X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR) results show that the surface reducibility depends on whether the Rh is in (or supported on) the LZ pyrochlore. Rhodium in the LRZ is more reducible than rhodium supported on the R/LZ pyrochlore, likely due to the presence of a perovskite phase (LaRhO{sub 3}; identified by XRD), in which rhodium is more reducible. The formation of the perovskite accompanies that of the pyrochlore. CO hydrogenation results show higher ethanol selectivity for R/LZ than LRZ, possibly due to the strong interaction between Rh and LZ on the R/LZ, forming atomically close Rh{sup +}/Rh{sup 0} sites, which have been suggested to favor ethanol production.

  18. Arranging ISO 13606 archetypes into a knowledge base using UML connectors.

    PubMed

    Kopanitsa, Georgy

    2014-01-01

    To enable the efficient reuse of standard based medical data we propose to develop a higher-level information model that will complement the archetype model of ISO 13606. This model will make use of the relationships that are specified in UML to connect medical archetypes into a knowledge base within a repository. UML connectors were analysed for their ability to be applied in the implementation of a higher-level model that will establish relationships between archetypes. An information model was developed using XML Schema notation. The model allows linking different archetypes of one repository into a knowledge base. Presently it supports several relationships and will be advanced in future.

  19. Recurrent motifs as resonant attractor states in the narrative field: a testable model of archetype.

    PubMed

    Goodwyn, Erik

    2013-06-01

    At the most basic level, archetypes represented Jung's attempt to explain the phenomenon of recurrent myths and folktale motifs (Jung 1956, 1959, para. 99). But the archetype remains controversial as an explanation of recurrent motifs, as the existence of recurrent motifs does not prove that archetypes exist. Thus, the challenge for contemporary archetype theory is not merely to demonstrate that recurrent motifs exist, since that is not disputed, but to demonstrate that archetypes exist and cause recurrent motifs. The present paper proposes a new model which is unlike others in that it postulates how the archetype creates resonant motifs. This model necessarily clarifies and adapts some of Jung's seminal ideas on archetype in order to provide a working framework grounded in contemporary practice and methodologies. For the first time, a model of archetype is proposed that can be validated on empirical, rather than theoretical grounds. This is achieved by linking the archetype to the hard data of recurrent motifs rather than academic trends in other fields.

  20. Arranging ISO 13606 archetypes into a knowledge base using UML connectors.

    PubMed

    Kopanitsa, Georgy

    2014-01-01

    To enable the efficient reuse of standard based medical data we propose to develop a higher-level information model that will complement the archetype model of ISO 13606. This model will make use of the relationships that are specified in UML to connect medical archetypes into a knowledge base within a repository. UML connectors were analysed for their ability to be applied in the implementation of a higher-level model that will establish relationships between archetypes. An information model was developed using XML Schema notation. The model allows linking different archetypes of one repository into a knowledge base. Presently it supports several relationships and will be advanced in future. PMID:24743069

  1. A narratological methodology for identifying archetypal story patterns in autobiographical narratives.

    PubMed

    Roesler, Christian

    2006-09-01

    Based on Jung's definition of archetype the concept 'archetypal story pattern' is developed as well as a research method drawing on narrative analysis and biographical research to identify these archetypal story patterns in life stories. Jung pointed out that personal myths, archetypal patterns found, e.g., in mythology, can govern the life course of individuals unconsciously. In the Theory of Narrative Identity comparable concepts have been mentioned but were never fully developed. In my research I try to combine Jung's concept of the archetype with the elaborated methodology of narrative analysis. Archetypes can manifest as narratives and the identity construction of a person via narrating the life story can be influenced or even totally structured by archetypal stories which give a specific form as well as a specific meaning to the person's identity. The method of extracting an underlying archetypal pattern from an autobiographical narrative is demonstrated. The results of the research on 20 autobiographical interviews and the inherent archetypal patterns are summarized. The major aim of this paper is to describe in detail the application of a well established method of the social sciences on a key concept of Jungian psychology to show that these concepts can be integrated into recent research frameworks of academic sciences. On the other hand it shows that Jungian concepts can be investigated through established and well defined research methods in empirical research settings.

  2. A narratological methodology for identifying archetypal story patterns in autobiographical narratives.

    PubMed

    Roesler, Christian

    2006-09-01

    Based on Jung's definition of archetype the concept 'archetypal story pattern' is developed as well as a research method drawing on narrative analysis and biographical research to identify these archetypal story patterns in life stories. Jung pointed out that personal myths, archetypal patterns found, e.g., in mythology, can govern the life course of individuals unconsciously. In the Theory of Narrative Identity comparable concepts have been mentioned but were never fully developed. In my research I try to combine Jung's concept of the archetype with the elaborated methodology of narrative analysis. Archetypes can manifest as narratives and the identity construction of a person via narrating the life story can be influenced or even totally structured by archetypal stories which give a specific form as well as a specific meaning to the person's identity. The method of extracting an underlying archetypal pattern from an autobiographical narrative is demonstrated. The results of the research on 20 autobiographical interviews and the inherent archetypal patterns are summarized. The major aim of this paper is to describe in detail the application of a well established method of the social sciences on a key concept of Jungian psychology to show that these concepts can be integrated into recent research frameworks of academic sciences. On the other hand it shows that Jungian concepts can be investigated through established and well defined research methods in empirical research settings. PMID:16918800

  3. Recurrent motifs as resonant attractor states in the narrative field: a testable model of archetype.

    PubMed

    Goodwyn, Erik

    2013-06-01

    At the most basic level, archetypes represented Jung's attempt to explain the phenomenon of recurrent myths and folktale motifs (Jung 1956, 1959, para. 99). But the archetype remains controversial as an explanation of recurrent motifs, as the existence of recurrent motifs does not prove that archetypes exist. Thus, the challenge for contemporary archetype theory is not merely to demonstrate that recurrent motifs exist, since that is not disputed, but to demonstrate that archetypes exist and cause recurrent motifs. The present paper proposes a new model which is unlike others in that it postulates how the archetype creates resonant motifs. This model necessarily clarifies and adapts some of Jung's seminal ideas on archetype in order to provide a working framework grounded in contemporary practice and methodologies. For the first time, a model of archetype is proposed that can be validated on empirical, rather than theoretical grounds. This is achieved by linking the archetype to the hard data of recurrent motifs rather than academic trends in other fields. PMID:23750942

  4. Order by virtual crystal field fluctuations in pyrochlore XY antiferromagnets

    NASA Astrophysics Data System (ADS)

    Rau, Jeffrey G.; Petit, Sylvain; Gingras, Michel J. P.

    2016-05-01

    Conclusive evidence of order by disorder is scarce in real materials. Perhaps one of the strongest cases presented has been for the pyrochlore XY antiferromagnet Er2Ti2O7 , with the ground state selection proceeding by order by disorder induced through the effects of quantum fluctuations. This identification assumes the smallness of the effect of virtual crystal field fluctuations that could provide an alternative route to picking the ground state. Here we show that this order by virtual crystal field fluctuations is not only significant, but competitive with the effects of quantum fluctuations. Further, we argue that higher-multipolar interactions that are generically present in rare-earth magnets can dramatically enhance this effect. From a simplified bilinear-biquadratic model of these multipolar interactions, we show how the virtual crystal field fluctuations manifest in Er2Ti2O7 using a combination of strong-coupling perturbation theory and the random-phase approximation. We find that the experimentally observed ψ2 state is indeed selected and the experimentally measured excitation gap can be reproduced when the bilinear and biquadratic couplings are comparable while maintaining agreement with the entire experimental spin-wave excitation spectrum. Finally, we comment on possible tests of this scenario and discuss implications for other order-by-disorder candidates in rare-earth magnets.

  5. Magnetic order in the double pyrochlore Tb₂Ru₂O₇.

    PubMed

    Chang, L J; Prager, M; Persson, J; Walter, J; Jansen, E; Chen, Y Y; Gardner, J S

    2010-02-24

    Polycrystalline Tb(2)Ru(2)O(7) has been studied using dc susceptibility, specific heat and neutron scattering techniques. The high temperature paramagnetic state is dominated by the single ion character of Tb(3 + ) and very similar to that of the well-studied spin liquid Tb(2)Ti(2)O(7). However, both the Ru(4 + ) and Tb(3 + ) sublattices order, at about 110 K and 3.5 K, respectively. Although the Tb sublattice does not fully order until 3.5 K, it is polarized in the presence of the internal field generated by the Ru(4 + ) sublattice and possesses a significant moment at 7 K. Magnetic entropy measurements suggest that four levels exist in the first 30 K and inelastic neutron scattering investigations revealed two more levels at 10 and 14 meV. As the magnetic sublattices order, the excitations are perturbed from that measured in the paramagnetic state. These data are compared to data for other terbium based and double pyrochlores.

  6. Probing disorder in isometric pyrochlore and related complex oxides.

    PubMed

    Shamblin, Jacob; Feygenson, Mikhail; Neuefeind, Joerg; Tracy, Cameron L; Zhang, Fuxiang; Finkeldei, Sarah; Bosbach, Dirk; Zhou, Haidong; Ewing, Rodney C; Lang, Maik

    2016-05-01

    There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under extreme conditions. Despite the importance of the disordering process there exists only a limited understanding of the role of local ordering on the energy landscape. We have used neutron total scattering to show that disordered fluorite (induced intrinsically by composition/stoichiometry or at far-from-equilibrium conditions produced by high-energy radiation) consists of a local orthorhombic structural unit that is repeated by a pseudo-translational symmetry, such that orthorhombic and isometric arrays coexist at different length scales. We also show that inversion in isometric spinel occurs by a similar process. This insight provides a new basis for understanding order-to-disorder transformations important for applications such as plutonium immobilization, fast ion conduction, and thermal barrier coatings. PMID:26928636

  7. Probing disorder in isometric pyrochlore and related complex oxides

    NASA Astrophysics Data System (ADS)

    Shamblin, Jacob; Feygenson, Mikhail; Neuefeind, Joerg; Tracy, Cameron L.; Zhang, Fuxiang; Finkeldei, Sarah; Bosbach, Dirk; Zhou, Haidong; Ewing, Rodney C.; Lang, Maik

    2016-05-01

    There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under extreme conditions. Despite the importance of the disordering process there exists only a limited understanding of the role of local ordering on the energy landscape. We have used neutron total scattering to show that disordered fluorite (induced intrinsically by composition/stoichiometry or at far-from-equilibrium conditions produced by high-energy radiation) consists of a local orthorhombic structural unit that is repeated by a pseudo-translational symmetry, such that orthorhombic and isometric arrays coexist at different length scales. We also show that inversion in isometric spinel occurs by a similar process. This insight provides a new basis for understanding order-to-disorder transformations important for applications such as plutonium immobilization, fast ion conduction, and thermal barrier coatings.

  8. Bismuth pyrochlore thin films for dielectric energy storage

    SciTech Connect

    Michael, Elizabeth K. Trolier-McKinstry, Susan

    2015-08-07

    Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate were fabricated using chemical solution deposition. This family of materials exhibited moderate relative permittivities between 55 ± 2 and 145 ± 5 for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 ± 0.0001. Increases in the concentration of the tantalum end member increased the dielectric breakdown strength. For example, at 10 kHz, the room temperature breakdown strength of bismuth zinc niobate was 5.1 MV/cm, while that of bismuth zinc tantalate was 6.1 MV/cm. This combination of a high breakdown strength and a moderate permittivity led to a high discharged energy storage density for all film compositions. For example, at a measurement frequency of 10 kHz, bismuth zinc niobate exhibited a maximum recoverable energy storage density of 60.8 ± 2.0 J/cm{sup 3}, while bismuth zinc tantalate exhibited a recoverable energy storage density of 60.7 ± 2.0 J/cm{sup 3}. Intermediate compositions of bismuth zinc niobate tantalate offered higher energy storage densities; at 10 mol. % tantalum, the maximum recoverable energy storage density was ∼66.9 ± 2.4 J/cm{sup 3}.

  9. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    DOE PAGESBeta

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-02-29

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. As a result, the epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystallinemore » Ir nanocrystals.« less

  10. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    NASA Astrophysics Data System (ADS)

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-02-01

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. The epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystalline Ir nanocrystals.

  11. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    PubMed Central

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-01-01

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. The epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystalline Ir nanocrystals. PMID:26923862

  12. Insights into the radiation response of pyrochlores from calculations of threshold displacement events

    NASA Astrophysics Data System (ADS)

    Devanathan, R.; Weber, W. J.

    2005-10-01

    We have used molecular-dynamics simulations to examine the displacement threshold energy (Ed) surface for cations and anions in Gd2Ti2O7 and Gd2Zr2O7 pyrochlores. In both pyrochlores, the Ed surface is highly anisotropic and it requires less energy to displace anions than cations. Both anion and cation Ed values are higher in the titanate compared to the zirconate. Titanium displacement energies are in excess of 170 eV for all directions examined, because cation exchange is less energetically favorable in Gd2Ti2O7 compared to Gd2Zr2O7. These high-energy Ti displacements result in the formation of defect clusters that may prevent efficient defect recovery. This provides an explanation for the difference in susceptibility to amorphization between titanate and zirconate pyrochlores.

  13. Electronic excitation induced amorphization in titanate pyrochlores: an ab initio molecular dynamics study

    DOE PAGESBeta

    Xiao, Haiyan Y.; Weber, William J.; Zhang, Yanwen; Zu, X. T.; Li, Sean

    2015-02-09

    In this study, the response of titanate pyrochlores (A2Ti2O7, A = Y, Gd and Sm) to electronic excitation is investigated utilizing an ab initio molecular dynamics method. All the titanate pyrochlores are found to undergo a crystalline-to-amorphous structural transition under a low concentration of electronic excitations. The transition temperature at which structural amorphization starts to occur depends on the concentration of electronic excitations. During the structural transition, O2-like molecules are formed, and this anion disorder further drives cation disorder that leads to an amorphous state. This study provides new insights into the mechanisms of amorphization in titanate pyrochlores under laser,more » electron and ion irradiations.« less

  14. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films.

    PubMed

    Gallagher, J C; Esser, B D; Morrow, R; Dunsiger, S R; Williams, R E A; Woodward, P M; McComb, D W; Yang, F Y

    2016-02-29

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. The epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystalline Ir nanocrystals.

  15. Approaching the Heisenberg Limit without Single-Particle Detection.

    PubMed

    Davis, Emily; Bentsen, Gregory; Schleier-Smith, Monika

    2016-02-01

    We propose an approach to quantum phase estimation that can attain precision near the Heisenberg limit without requiring single-particle-resolved state detection. We show that the "one-axis twisting" interaction, well known for generating spin squeezing in atomic ensembles, can also amplify the output signal of an entanglement-enhanced interferometer to facilitate readout. Applying this interaction-based readout to oversqueezed, non-Gaussian states yields a Heisenberg scaling in phase sensitivity, which persists in the presence of detection noise as large as the quantum projection noise of an unentangled ensemble. Even in dissipative implementations-e.g., employing light-mediated interactions in an optical cavity or Rydberg dressing-the method significantly relaxes the detection resolution required for spectroscopy beyond the standard quantum limit. PMID:26894711

  16. Space Group Symmetry Fractionalization in a Chiral Kagome Heisenberg Antiferromagnet.

    PubMed

    Zaletel, Michael P; Zhu, Zhenyue; Lu, Yuan-Ming; Vishwanath, Ashvin; White, Steven R

    2016-05-13

    The anyonic excitations of a spin liquid can feature fractional quantum numbers under space group symmetries. Detecting these fractional quantum numbers, which are analogs of the fractional charge of Laughlin quasiparticles, may prove easier than the direct observation of anyonic braiding and statistics. Motivated by the recent numerical discovery of spin-liquid phases in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern of space group symmetry fractionalization in the kagome lattice SO(3)-symmetric chiral spin liquid. We provide a method to detect these fractional quantum numbers in finite-size numerics which is simple to implement in the density matrix renormalization group. Applying these developments to the chiral spin liquid phase of a kagome Heisenberg model, we find perfect agreement between our theoretical prediction and numerical observations. PMID:27232041

  17. Heisenberg picture approach to the stability of quantum Markov systems

    SciTech Connect

    Pan, Yu E-mail: zibo.miao@anu.edu.au; Miao, Zibo E-mail: zibo.miao@anu.edu.au; Amini, Hadis; Gough, John; Ugrinovskii, Valery; James, Matthew R.

    2014-06-15

    Quantum Markovian systems, modeled as unitary dilations in the quantum stochastic calculus of Hudson and Parthasarathy, have become standard in current quantum technological applications. This paper investigates the stability theory of such systems. Lyapunov-type conditions in the Heisenberg picture are derived in order to stabilize the evolution of system operators as well as the underlying dynamics of the quantum states. In particular, using the quantum Markov semigroup associated with this quantum stochastic differential equation, we derive sufficient conditions for the existence and stability of a unique and faithful invariant quantum state. Furthermore, this paper proves the quantum invariance principle, which extends the LaSalle invariance principle to quantum systems in the Heisenberg picture. These results are formulated in terms of algebraic constraints suitable for engineering quantum systems that are used in coherent feedback networks.

  18. q-graded Heisenberg algebras and deformed supersymmetries

    SciTech Connect

    Ben Geloun, Joseph; Hounkonnou, Mahouton Norbert

    2010-02-15

    The notion of q-grading on the enveloping algebra generated by products of q-deformed Heisenberg algebras is introduced for q complex number in the unit disk. Within this formulation, we consider the extension of the notion of supersymmetry in the enveloping algebra. We recover the ordinary Z{sub 2} grading or Grassmann parity for associative superalgebra and a modified version of the usual supersymmetry. As a specific problem, we focus on the interesting limit q{yields}-1 for which the Arik and Coon deformation [J. Math. Phys. 17, 524 (1976)] of the Heisenberg algebra allows one to map fermionic modes to bosonic ones in a modified sense. Different algebraic consequences are discussed.

  19. Far-from-equilibrium spin transport in Heisenberg quantum magnets.

    PubMed

    Hild, Sebastian; Fukuhara, Takeshi; Schauß, Peter; Zeiher, Johannes; Knap, Michael; Demler, Eugene; Bloch, Immanuel; Gross, Christian

    2014-10-01

    We study experimentally the far-from-equilibrium dynamics in ferromagnetic Heisenberg quantum magnets realized with ultracold atoms in an optical lattice. After controlled imprinting of a spin spiral pattern with an adjustable wave vector, we measure the decay of the initial spin correlations through single-site resolved detection. On the experimentally accessible time scale of several exchange times, we find a profound dependence of the decay rate on the wave vector. In one-dimensional systems, we observe diffusionlike spin transport with a dimensionless diffusion coefficient of 0.22(1). We show how this behavior emerges from the microscopic properties of the closed quantum system. In contrast to the one-dimensional case, our transport measurements for two-dimensional Heisenberg systems indicate anomalous superdiffusion. PMID:25325657

  20. Spin dynamics simulations for a nanoscale Heisenberg antiferromagnet

    NASA Astrophysics Data System (ADS)

    Hou, Zhuofei; Landau, D. P.; Brown, G.; Stocks, G. M.

    2010-03-01

    Thermoinduced magnetization(TiM) is a novel response which was predicted to occur in nanoscale antiferromagnetic materials. Extensive Monte Carlo simulations footnotetextG. Brown, A. Janotti, M. Eisenbach, and G. M. Stocks, Phys.Rev.B 72, 140405(2005) have shown that TiM is an intrinsic property of the antiferromagnetic classical Heisenberg model below the Neel temperature. To obtain a fundamental understanding of TiM, spin dynamics(SD) simulations are performed to study the spin wave behavior, which seems to be the cause of TiM. A classical Heisenberg model with an antiferromagnetic nearest-neighbor exchange interaction and uniaxial single-site anisotropy is studied. Simple-cubic lattices with free boundary conditions are used. We employed the fast spin dynamics algorithms with fourth-order Suzuki-Trotter decompositions of the exponential operator. Additional small excitation peaks due to surface effects are found in transverse S(q,w).

  1. The role of phase space geometry in Heisenberg's uncertainty relation

    NASA Astrophysics Data System (ADS)

    Anastopoulos, Charis; Savvidou, Ntina

    2003-11-01

    Aiming towards a geometric description of quantum theory, we study the coherent states-induced metric on the phase space, which provides a geometric formulation of the Heisenberg uncertainty relations (both the position-momentum and the time-energy ones). The metric also distinguishes the original uncertainty relations of Heisenberg from the ones that are obtained from non-commutativity of operators. Conversely, the uncertainty relations can be written in terms of this metric only, hence they can be formulated for any physical system, including ones with non-trivial phase space. Moreover, the metric is a key ingredient of the probability structure of continuous-time histories on phase space. This fact allows a simple new proof the impossibility of the physical manifestation of the quantum Zeno and anti-Zeno paradoxes. Finally, we construct the coherent states for a spinless relativistic particle, as a non-trivial example by which we demonstrate our results.

  2. Heisenberg-limited sensitivity with decoherence-enhanced measurements.

    PubMed

    Braun, Daniel; Martin, John

    2011-01-01

    Quantum-enhanced measurements use quantum mechanical effects to enhance the sensitivity of the measurement of classical quantities, such as the length of an optical cavity. The major goal is to beat the standard quantum limit (SQL), that is, an uncertainty of order , where N is the number of quantum resources (for example, the number of photons or atoms used), and to achieve a scaling 1/N, known as the Heisenberg limit. So far very few experiments have demonstrated an improvement over the SQL. The required quantum states are generally highly entangled, difficult to produce, and very prone to decoherence. Here, we show that Heisenberg-limited measurements can be achieved without the use of entangled states by coupling the quantum resources to a common environment that can be measured at least in part. The method is robust under decoherence, and in fact the parameter dependence of collective decoherence itself can be used to reach a 1/N scaling.

  3. Archetype based search in an IHE XDS environment.

    PubMed

    Rinner, Christoph; Kohler, Michael; Hübner-Bloder, Gudrun; Saboor, Samrend; Ammenwerth, Elske; Duftschmid, Georg

    2012-01-01

    To prevent information overload of physicians when accessing EHRs we introduce a method to extend the IHE XDS profile metadata-based search towards a content-based search. Detailed queries are created based on predefined information needs mapped to ISO/EN 13606 Archetypes. They are aggregated to a metadata-based query to retrieve all relevant documents, which are then analyzed for the desired contents. The results are presented in a tabular form. The content-based search in IHE-XDS could be implemented efficiently and was found helpful by the evaluating physicians.

  4. Archetype based search in an IHE XDS environment.

    PubMed

    Rinner, Christoph; Kohler, Michael; Hübner-Bloder, Gudrun; Saboor, Samrend; Ammenwerth, Elske; Duftschmid, Georg

    2012-01-01

    To prevent information overload of physicians when accessing EHRs we introduce a method to extend the IHE XDS profile metadata-based search towards a content-based search. Detailed queries are created based on predefined information needs mapped to ISO/EN 13606 Archetypes. They are aggregated to a metadata-based query to retrieve all relevant documents, which are then analyzed for the desired contents. The results are presented in a tabular form. The content-based search in IHE-XDS could be implemented efficiently and was found helpful by the evaluating physicians. PMID:22874268

  5. Spatially frustrated S = 1 Heisenberg antiferromagnet with single ion anisotropy

    NASA Astrophysics Data System (ADS)

    Pires, A. S. T.

    2016-10-01

    Using the SU(3) Schwinger boson formalism, I study the S = 1 square lattice Heisenberg antiferromagnet, at zero temperature, with spatially anisotropic nearest-neighbor couplings frustrated by a next-nearest neighbor interaction and single ion anisotropy. The phase diagram at zero temperature is presented. My calculations show two magnetically ordered phases separated by a quantum-disordered region for all values of the anisotropy.

  6. Decay of transverse correlations in quantum Heisenberg models

    SciTech Connect

    Björnberg, Jakob E. E-mail: daniel@ueltschi.org; Ueltschi, Daniel E-mail: daniel@ueltschi.org

    2015-04-15

    We study a class of quantum spin systems that include the S=1/2 Heisenberg and XY-models and prove that two-point correlations exhibit exponential decay in the presence of a transverse magnetic field. The field is not necessarily constant, it may be random, and it points in the same direction. Our proof is entirely probabilistic and it relies on a random loop representations of the correlation functions, on stochastic domination and on first-passage percolation.

  7. Type-I integrable quantum impurities in the Heisenberg model

    NASA Astrophysics Data System (ADS)

    Doikou, Anastasia

    2013-12-01

    Type-I quantum impurities are investigated in the context of the integrable Heisenberg model. This type of defects is associated to the (q)-harmonic oscillator algebra. The transmission matrices associated to this particular type of defects are computed via the Bethe ansatz methodology for the XXX model, as well as for the critical and non-critical XXZ spin chain. In the attractive regime of the critical XXZ spin chain the transmission amplitudes for the breathers are also identified.

  8. Single-ion anisotropy in the gadolinium pyrochlores studied by electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Glazkov, V. N.; Zhitomirsky, M. E.; Smirnov, A. I.; Krug von Nidda, H.-A.; Loidl, A.; Marin, C.; Sanchez, J.-P.

    2005-07-01

    The electron paramagnetic resonance is used to measure the single-ion anisotropy of Gd3+ ions in the pyrochlore structure of (Y1-xGdx)2Ti2O7 . A rather strong easy-plane-type anisotropy is found. The anisotropy constant D is comparable to the exchange integral J in the prototype Gd2Ti2O7 , D≃0.75J , and exceeds the dipolar energy scale. Physical implications of an easy-plane anisotropy for a pyrochlore antiferromagnet are considered. We calculate the magnetization curves at T=0 and discuss phase transitions in a magnetic field.

  9. Global phase diagram of a doped Kitaev-Heisenberg model

    SciTech Connect

    Okamoto, Satoshi

    2013-01-01

    The global phase diagram of a doped Kitaev-Heisenberg model is studied using an $SU(2)$ slave-boson mean-field method. Near the Kitaev limit, $p$-wave superconducting states which break the time-reversal symmetry are stabilized as reported by You {\\it et al.} [Phys. Rev. B {\\bf 86}, 085145 (2012)] irrespective of the sign of the Kitaev interaction. By further doping, a $d$-wave superconducting state appears when the Kitaev interaction is antiferromagnetic, while another $p$-wave superconducting state appears when the Kitaev interaction is ferromagnetic. This $p$-wave superconducting state does not break the time-reversal symmetry as reported by Hyart {\\it et al.} [Phys. Rev. B {\\bf 85}, 140510 (2012)], and such a superconducting state also appears when the antiferromagnetic Kitaev interaction and the ferromagnetic Heisenberg interaction compete. This work, thus, demonstrates the clear difference between the antiferromagnetic Kitaev model and the ferromagnetic Kitaev model when carriers are doped while these models are equivalent in the undoped limit, and how novel superconducting states emerge when the Kitaev interaction and the Heisenberg interaction compete.

  10. Birth/Death/Rebirth: Pairing Young Adult and Classic Novels To Teach Situational Archetypes.

    ERIC Educational Resources Information Center

    Sanderson, Christine

    2001-01-01

    Notes that the use of Young Adult literature to introduce the complex literary concept of the archetype is ideally suited to teachers of gifted students in high school classrooms. Discusses how once students understand the concept of archetypes in literature, they can begin to make deeper connections among all of the literary works that they read.…

  11. Principle of organization: a dynamic-systems view of the archetype-as-such.

    PubMed

    McDowell, M J

    2001-10-01

    The personality is a dynamic system. Like all other dynamic systems, it must be self-organized. In this paper I focus upon the archetype-as-such, that is, upon the essential core around which both an archetypical image and a complex are organized. I argue that an archetype-as-such is a pre-existing principle of organization. Within the personality that principle manifests itself as a psychological vortex (a complex) into which we are drawn. The vortex is impersonal. We mediate it through myths and rituals or through consciousness. In this paper I show that Jung's intuition about the archetype-as-such is supported by recent science. I evaluate other concepts of the archetype. My concept is different from that proposed recently by Saunders and Skar. My concept allows each archetype-as-such to be defined precisely in mathematical terms. It suggests a new interpretation of mythology. It also addresses our spiritual experience of an archetype. Because the archetypes-as-such are fundamental to the personality, the better we understand them the better we understand our patients. The paper is grounded with clinical examples.

  12. A reappraisal of classical archetype theory and its implications for theory and practice.

    PubMed

    Merchant, John

    2009-06-01

    This paper begins with an overview of contemporary approaches to archetype theory and notes the radical nature of certain deductions. Some argue that there is no 'archetype-as-such' as a pre-existing entity at the core of a complex driving its formation whilst the findings of current neuroscience are calling into question one very thing on which the classical theory is built--innatism. Knox's argument for image schemas raises the question as to the extent to which archetypes can be conceived in any preformationist sense. The question is then posed--to what extent can Jung's classical theory of archetypes be read in light of these current models? The case examples Jung uses to evidence the existence of archetypes, his explications of synchronicity and his own Philemon experience are then reappraised. The conclusion is drawn that it is difficult to evidence the existence of autonomous archetypes unrelated to personal affective experience. Not only would this be expected by emergent/developmental models of archetype but it can explain many of Jung's disjunctive statements about archetype constellation; the difficulties in separating personal and collective psychic content and Jung's apparent Lamarckianism. The implications of these models for theory, clinical practice and analyst training are then offered for discussion.

  13. Male Archetypes as Resources for Homosexual Identity Development in Gay Men.

    ERIC Educational Resources Information Center

    McFarland, William P.; McMahon, Timothy R.

    1999-01-01

    The male archetypes of king, lover, magician, and warrior provide important and timeless insights into mature masculine qualities. Homosexual identity development models describe tasks that confront gay men as they move through the identity development process. Proposes that by understanding the metaphor of male archetypes, gay men will discover…

  14. Punishment and Forgiveness: A Phenomenological Analysis of Archetypal Leadership Patterns and the Implications for Educational Practice

    ERIC Educational Resources Information Center

    Abramson, Neil Remington; Senyshyn, Yaroslav

    2009-01-01

    Archetypal psychology suggests the possibility of a punishment archetype representing the unconscious preferences of human beings as a species about what constitutes appropriate ways for leaders (students, teachers and educational leaders) to correct followers who do harm to others. Mythological analysis compared God's process of punishment, in…

  15. "In the Labyrinth of the Image": An Archetypal Approach to Drama in Education.

    ERIC Educational Resources Information Center

    Haine, Gano

    1985-01-01

    This article delineates an archetypal approach to drama in education. Participation in drama draws on both conscious and unconscious imaginative capabilities and involves teacher and student in the bedrock of human reaction. Drama could provide us with valuable information concerning archetypes as they unfold in the lives of our children. (MT)

  16. Reclaiming the Maiden: Use of Archetypes in a 6-Week Women's Empowerment Group

    ERIC Educational Resources Information Center

    Singh, Anneliese; Hofsess, Christy D.

    2011-01-01

    The purpose of this article is to describe a 6-week, semi-structured group counseling experience for university women students (undergraduate and graduate) from diverse backgrounds exploring archetypes and using group empowerment skills. Theoretical perspectives on women's empowerment groups and the use of archetypes in counseling are discussed as…

  17. Qualitative Research as a Hero's Journey: Six Archetypes to Draw on

    ERIC Educational Resources Information Center

    Villate, Vanessa M.

    2012-01-01

    Is the research process similar to a hero's journey? Just as a hero draws on different archetypes during the journey, a researcher moves through phases and must draw upon different strengths. In this article, the six archetypes that Pearson (1998) links to the hero's journey are described. Then, each phase of a qualitative research study is…

  18. Eco-Heroes and Eco-Villains: An Archetypal Analysis of Environmental Film, 1950-2010

    ERIC Educational Resources Information Center

    Roberts, Candice D.; Stein, Susan

    2015-01-01

    Archetypes are characters recognizable by media consumers that operate at a subconscious level and often elicit strong emotional responses. Popular Hollywood films addressing issues of the environment offer hero and villain figures that demonstrate strong archetypal characteristics. Surrounding the intricate characters, many of these films also…

  19. A reappraisal of classical archetype theory and its implications for theory and practice.

    PubMed

    Merchant, John

    2009-06-01

    This paper begins with an overview of contemporary approaches to archetype theory and notes the radical nature of certain deductions. Some argue that there is no 'archetype-as-such' as a pre-existing entity at the core of a complex driving its formation whilst the findings of current neuroscience are calling into question one very thing on which the classical theory is built--innatism. Knox's argument for image schemas raises the question as to the extent to which archetypes can be conceived in any preformationist sense. The question is then posed--to what extent can Jung's classical theory of archetypes be read in light of these current models? The case examples Jung uses to evidence the existence of archetypes, his explications of synchronicity and his own Philemon experience are then reappraised. The conclusion is drawn that it is difficult to evidence the existence of autonomous archetypes unrelated to personal affective experience. Not only would this be expected by emergent/developmental models of archetype but it can explain many of Jung's disjunctive statements about archetype constellation; the difficulties in separating personal and collective psychic content and Jung's apparent Lamarckianism. The implications of these models for theory, clinical practice and analyst training are then offered for discussion. PMID:19531124

  20. Innovative Robot Archetypes for In-Space Construction and Maintenance

    NASA Technical Reports Server (NTRS)

    Rehnmark, Fredrik; Ambrose, Robert O.; Kennedy, Brett; Diftler, Myron; Mehling Joshua; Brigwater, Lyndon; Radford, Nicolaus; Goza, S. Michael; Culbert, Christopher

    2005-01-01

    The space environment presents unique challenges and opportunities in the assembly, inspection and maintenance of orbital and transit spaceflight systems. While conventional Extra-Vehicular Activity (EVA) technology, out of necessity, addresses each of the challenges, relatively few of the opportunities have been exploited due to crew safety and reliability considerations. Extra-Vehicular Robotics (EVR) is one of the least-explored design spaces but offers many exciting innovations transcending the crane-like Space Shuttle and International Space Station Remote Manipulator System (RMS) robots used for berthing, coarse positioning and stabilization. Microgravity environments can support new robotic archetypes with locomotion and manipulation capabilities analogous to undersea creatures. Such diversification could enable the next generation of space science platforms and vehicles that are too large and fragile to launch and deploy as self-contained payloads. Sinuous manipulators for minimally invasive inspection and repair in confined spaces, soft-stepping climbers with expansive leg reach envelopes and free-flying nanosatellite cameras can access EVA worksites generally not accessible to humans in spacesuits. These and other novel robotic archetypes are presented along with functionality concepts

  1. A Process for the Representation of openEHR ADL Archetypes in OWL Ontologies.

    PubMed

    Porn, Alex Mateus; Peres, Leticia Mara; Didonet Del Fabro, Marcos

    2015-01-01

    ADL is a formal language to express archetypes, independent of standards or domain. However, its specification is not precise enough in relation to the specialization and semantic of archetypes, presenting difficulties in implementation and a few available tools. Archetypes may be implemented using other languages such as XML or OWL, increasing integration with Semantic Web tools. Exchanging and transforming data can be better implemented with semantics oriented models, for example using OWL which is a language to define and instantiate Web ontologies defined by W3C. OWL permits defining significant, detailed, precise and consistent distinctions among classes, properties and relations by the user, ensuring the consistency of knowledge than using ADL techniques. This paper presents a process of an openEHR ADL archetypes representation in OWL ontologies. This process consists of ADL archetypes conversion in OWL ontologies and validation of OWL resultant ontologies using the mutation test. PMID:26262167

  2. A Process for the Representation of openEHR ADL Archetypes in OWL Ontologies.

    PubMed

    Porn, Alex Mateus; Peres, Leticia Mara; Didonet Del Fabro, Marcos

    2015-01-01

    ADL is a formal language to express archetypes, independent of standards or domain. However, its specification is not precise enough in relation to the specialization and semantic of archetypes, presenting difficulties in implementation and a few available tools. Archetypes may be implemented using other languages such as XML or OWL, increasing integration with Semantic Web tools. Exchanging and transforming data can be better implemented with semantics oriented models, for example using OWL which is a language to define and instantiate Web ontologies defined by W3C. OWL permits defining significant, detailed, precise and consistent distinctions among classes, properties and relations by the user, ensuring the consistency of knowledge than using ADL techniques. This paper presents a process of an openEHR ADL archetypes representation in OWL ontologies. This process consists of ADL archetypes conversion in OWL ontologies and validation of OWL resultant ontologies using the mutation test.

  3. Archetype-based electronic health records: a literature review and evaluation of their applicability to health data interoperability and access.

    PubMed

    Wollersheim, Dennis; Sari, Anny; Rahayu, Wenny

    2009-01-01

    Health Information Managers (HIMs) are responsible for overseeing health information. The change management necessary during the transition to electronic health records (EHR) is substantial, and ongoing. Archetype-based EHRs are a core health information system component which solve many of the problems that arise during this period of change. Archetypes are models of clinical content, and they have many beneficial properties. They are interoperable, both between settings and through time. They are more amenable to change than conventional paradigms, and their design is congruent with clinical practice. This paper is an overview of the current archetype literature relevant to Health Information Managers. The literature was sourced in the English language sections of ScienceDirect, IEEE Explore, Pubmed, Google Scholar, ACM Digital library and other databases on the usage of archetypes for electronic health record storage, looking at the current areas of archetype research, appropriate usage, and future research. We also used reference lists from the cited papers, papers referenced by the openEHR website, and the recommendations from experts in the area. Criteria for inclusion were (a) if studies covered archetype research and (b) were either studies of archetype use, archetype system design, or archetype effectiveness. The 47 papers included show a wide and increasing worldwide archetype usage, in a variety of medical domains. Most of the papers noted that archetypes are an appropriate solution for future-proof and interoperable medical data storage. We conclude that archetypes are a suitable solution for the complex problem of electronic health record storage and interoperability.

  4. Insights into dynamic processes of cations in pyrochlores and other complex oxides

    SciTech Connect

    Uberuaga, Blas Pedro; Perriot, Romain

    2015-08-26

    Complex oxides are critical components of many key technologies, from solid oxide fuel cells and superionics to inert matrix fuels and nuclear waste forms. In many cases, understanding mass transport is important for predicting performance and, thus, extensive effort has been devoted to understanding mass transport in these materials. However, most work has focused on the behavior of oxygen while cation transport has received relatively little attention, even though cation diffusion is responsible for many phenomena, including sintering, radiation damage evolution, and deformation processes. Here, we use accelerated molecular dynamics simulations to examine the kinetics of cation defects in one class of complex oxides, A₂B₂O₇ pyrochlore. In some pyrochlore chemistries, B cation defects are kinetically unstable, transforming to A cation defects and antisites at rates faster than they can diffuse. When this occurs, transport of B cations occurs through defect processes on the A sublattice. Further, these A cation defects, either interstitials or vacancies, can interact with antisite disorder, reordering the material locally, though this process is much more efficient for interstitials than vacancies. Whether this behavior occurs in a given pyrochlore depends on the A and B chemistry. Pyrochlores with a smaller ratio of cation radii exhibit this complex behavior, while those with larger ratios exhibit direct migration of B interstitials. Similar behavior has been reported in other complex oxides such as spinels and perovskites, suggesting that this coupling of transport between the A and B cation sublattices, while not universal, occurs in many complex oxide.

  5. Magnetic and charge transport properties of the Na-based Os oxide pyrochlore

    SciTech Connect

    Shi, Y.G.; Belik, A.A.; Tachibana, M.; Tanaka, M.; Katsuya, Y.; Kobayashi, K.; Yamaura, K.; Takayama-Muromachi, E.

    2009-04-15

    The Na-based osmium oxide pyrochlore was synthesized for the first time by an ion-exchange method using KOs{sub 2}O{sub 6} as a host. The composition was identified as Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O by electron probe micro-analysis, thermogravimetric analysis, and structural analysis using synchrotron X-ray diffraction. Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O crystallizes in a regular pyrochlore structure with some defects (space group: Fd-3m, a=10.16851(1) A). Electrical resistivity, heat capacity, and magnetization measurements clearly showed absence of superconductivity down to 2 K, being in large contrast to what was found for the beta-type pyrochlore superconductor AOs{sub 2}O{sub 6} (A=Cs, Rb, and K). The Sommerfeld coefficient is 22 mJ K{sup -2} mol{sup -1}, being the smallest among AOs{sub 2}O{sub 6}. A magnetic anomaly at {approx}57 K and associated magneto-resistance (+3.7% at 2 K in 70 kOe) were found. - Graphical abstract: Crystal structure of the Na-based Os oxide pyrochlore Na{sub 1.4}Os{sub 2}O{sub 6}.H{sub 2}O.

  6. Curium-doped stannate pyrochlore: Durability under radiation and leaching in water

    NASA Astrophysics Data System (ADS)

    Yudintsev, S. V.; Tomilin, S. V.; Livshits, T. S.; Lizin, A. A.; Goryatchev, I. A.

    2016-07-01

    The radiation resistance of the phase (Gd,Cm)2Sn2O7 with a pyrochlore-type structure containing 3.0 wt % 244Cm was studied. It was established that amorphization occurs at a dose of 1019 α-decay/g (1.52 displacements per atom), which is 2-5 times higher than that needed for amorphization of titanate and titanate-zirconate pyrochlore phases with a similar structure. The heating of the amorphous ceramics restores the structure of the pyrochlore. The restoration process begins in the temperature interval of 600-700°C. This allows us to estimate the critical amorphization temperature as 650°C. On the 14th day, the rate of Cm leaching from the initial sample in water at 90°C is 10-1; Gd, 10-2; and Sn, 10-3 g/(m2 day). After amorphization the leaching rate increases by an order of magnitude (Cm) and two orders of magnitude (Gd), but it does not change for Sn. Compared to the zirconate and titanate-zirconate phases, stannate pyrochlore is markedly less resistant in water and cannot be regarded as a matrix for the immobilization of REE-actinide fraction wastes.

  7. Nature of the chemical bond and prediction of radiation tolerance in pyrochlore and defect fluorite compounds

    SciTech Connect

    Lumpkin, Gregory R. Pruneda, Miguel; Rios, Susana; Smith, Katherine L.; Trachenko, Kostya; Whittle, Karl R.; Zaluzec, Nestor J.

    2007-04-15

    The radiation tolerance of synthetic pyrochlore and defect fluorite compounds has been studied using ion irradiation. We show that the results can be quantified in terms of the critical temperature for amorphization, structural parameters, classical Pauling electronegativity difference, and disorder energies. Our results demonstrate that radiation tolerance is correlated with a change in the structure from pyrochlore to defect fluorite, a smaller unit cell dimension, and lower cation-anion disorder energy. Radiation tolerance is promoted by an increase in the Pauling cation-anion electronegativity difference or, in other words, an increase in the ionicity of the chemical bonds. A further analysis of the data indicates that, of the two possible cation sites in ideal pyrochlore, the smaller B-site cation appears to play the major role in bonding. This result is supported by ab initio calculations of the structure and bonding, showing a correlation between the Mulliken overlap populations of the B-site cation and the critical temperature. - Graphical abstract: Three-dimensional representation of the predicted critical amorphization temperature in pyrochlores.

  8. Calculation of the expected zero-field muon relaxation rate in the geometrically frustrated rare earth pyrochlore Gd(2)Sn(2)O(7) antiferromagnet.

    PubMed

    McClarty, P A; Cosman, J N; Del Maestro, A G; Gingras, M J P

    2011-04-27

    The magnetic insulator Gd(2)Sn(2)O(7) is one of many geometrically frustrated magnetic materials known to exhibit a nonzero muon spin polarization relaxation rate, λ(T), down to the lowest temperature (T) studied. Such behaviour is typically interpreted as signalling the presence of persistent spin dynamics (PSD) of the host material. In the case of Gd(2)Sn(2)O(7), such PSD comes as a surprise since magnetic specific heat measurements suggest conventional gapped magnons, which would naively lead to an exponentially vanishing λ(T) as T → 0. In contrast to most materials that display PSD, the ordered phase of Gd(2)Sn(2)O(7) is well characterized and both the nature and the magnitude of the interactions have been inferred from the magnetic structure and the temperature dependence of the magnetic specific heat. Based on this understanding, the temperature dependence of the muon spin polarization relaxation through the scattering of spin waves (magnons) is calculated. The result explicitly shows that, despite the unusual extensive number of weakly dispersive (gapped) excitations characterizing Gd(2)Sn(2)O(7), a remnant of the zero modes of the parent frustrated pyrochlore Heisenberg antiferromagnet, the temperature dependence of the calculated λ(T) differs dramatically from the experimental one. Indeed, the calculation conforms to the naive expectation of an exponential collapse of λ(T) at temperatures below ∼ 0.7 K. This result, for the first time, illustrates crisply and quantitatively the paradox that presents itself with the pervasive occurrence of PSD in highly frustrated magnetic systems as evinced by muon spin relaxation measurements.

  9. A curriculum framework based on archetypal phenomena and technologies

    NASA Astrophysics Data System (ADS)

    Zubrowski, Bernie

    2002-07-01

    The current crop of published curriculum materials for elementary and middle school makes various claims about their relevancy to the student and their alignment with national standards. Although it may appear that they show improvement in their pedagogical practices and use of recent research, it is argued that they still are founded on questionable assumptions about student learning. The general approach of these curriculum programs is examined in relationship to issues such as the context of learning, the relationship between domain general and domain specific knowledge, and the essential role that aesthetics and personal frameworks play in conceptual change. An alternative paradigm of curriculum development is presented based on the theory of situated cognition. This approach starts with context rather than concept, gives greater weight to students' interpretative frameworks, and provides for a more holistic development. A grade 1-8 framework is presented having archetypal phenomena and technologies as the focus of investigations.

  10. [The importance of the mother archetype in our day's Hungary].

    PubMed

    Süle, Ferenc

    2015-01-01

    The worsening demographic situation in our mother country as in Europe too call for the investigation of family life and the feminine role. We began the analysis of the developing problem with the investigation of the spirit of the age in which it appears. We examine the importance of the family life and the woman's role in the foundation of the future. We point out that in the archaic pattern of family life, the mother archetype functions as energy generator from the point of the family and the society. The children make it possible and necessary for the parents to live over again the whole process of human development. Through empathy they make possible the spontaneous corrective examination of the parents own deep psychological relational patterns. These make it certain that family life works psychologically as the source of energy, and workshop.

  11. [The importance of the mother archetype in our day's Hungary].

    PubMed

    Süle, Ferenc

    2015-01-01

    The worsening demographic situation in our mother country as in Europe too call for the investigation of family life and the feminine role. We began the analysis of the developing problem with the investigation of the spirit of the age in which it appears. We examine the importance of the family life and the woman's role in the foundation of the future. We point out that in the archaic pattern of family life, the mother archetype functions as energy generator from the point of the family and the society. The children make it possible and necessary for the parents to live over again the whole process of human development. Through empathy they make possible the spontaneous corrective examination of the parents own deep psychological relational patterns. These make it certain that family life works psychologically as the source of energy, and workshop. PMID:26771695

  12. The Archetype-enabled EHR system ZK-ARCHE - integrating the ISO/EN 13606 standard and IHE XDS profile.

    PubMed

    Kohler, Michael; Rinner, Christoph; Hübner-Bloder, Gudrun; Saboor, Samrend; Ammenwerth, Elske; Duftschmid, Georg

    2011-01-01

    The EHR system ZK-ARCHE automatically generates forms from ISO/EN 13606 archetypes. For this purpose the archetypes are augmented with components of the reference model to achieve so-called "comprehensive archetypes". Data collected via the forms are stored in a list which associates each value with the path of the corresponding comprehensive archetype node coded as W3C XPath. From this list archetype-conformant EHR extracts can be created. The system is embedded with the IHE XDS profile to allow direct data exchange in an environment of distributed data storage.

  13. Q-operators for the open Heisenberg spin chain

    NASA Astrophysics Data System (ADS)

    Frassek, Rouven; Szécsényi, István M.

    2015-12-01

    We construct Q-operators for the open spin-1/2 XXX Heisenberg spin chain with diagonal boundary matrices. The Q-operators are defined as traces over an infinite-dimensional auxiliary space involving novel types of reflection operators derived from the boundary Yang-Baxter equation. We argue that the Q-operators defined in this way are polynomials in the spectral parameter and show that they commute with transfer matrix. Finally, we prove that the Q-operators satisfy Baxter's TQ-equation and derive the explicit form of their eigenvalues in terms of the Bethe roots.

  14. Spin transport of weakly disordered Heisenberg chain at infinite temperature

    NASA Astrophysics Data System (ADS)

    Khait, Ilia; Gazit, Snir; Yao, Norman Y.; Auerbach, Assa

    2016-06-01

    We study the disordered Heisenberg spin chain, which exhibits many-body localization at strong disorder, in the weak to moderate disorder regime. A continued fraction calculation of dynamical correlations is devised, using a variational extrapolation of recurrents. Good convergence for the infinite chain limit is shown. We find that the local spin correlations decay at long times as C ˜t-β , whereas the conductivity exhibits a low-frequency power law σ ˜ωα . The exponents depict subdiffusive behavior β <1 /2 ,α >0 at all finite disorders and convergence to the scaling result α +2 β =1 at large disorders.

  15. Spin transport in a one-dimensional anisotropic Heisenberg model.

    PubMed

    Znidarič, Marko

    2011-06-01

    We analytically and numerically study spin transport in a one-dimensional Heisenberg model in linear-response regime at infinite temperature. It is shown that as the anisotropy parameter Δ is varied spin transport changes from ballistic for Δ<1 to anomalous at the isotropic point Δ=1, to diffusive for finite Δ>1, ending up as a perfect isolator in the Ising limit of infinite Δ. Using perturbation theory for large Δ a quantitative prediction is made for the dependence of diffusion constant on Δ. PMID:21702588

  16. Quantification of quantum discord in a antiferromagnetic Heisenberg compound

    SciTech Connect

    Singh, H. Chakraborty, T. Mitra, C.

    2014-04-24

    An experimental quantification of concurrence and quantum discord from heat capacity (C{sub p}) measurement performed over a solid state system has been reported. In this work, thermodynamic measurements were performed on copper nitrate (CN, Cu(NO{sub 3}){sub 2}⋅2.5H{sub 2}O) single crystals which is an alternating antiferromagnet Heisenberg spin 1/2 system. CN being a weak dimerized antiferromagnet is an ideal system to investigate correlations between spins. The theoretical expressions were used to obtain concurrence and quantum discord curves as a function of temperature from heat capacity data of a real macroscopic system, CN.

  17. Facilitating secondary use of medical data by using openEHR archetypes.

    PubMed

    Kohl, Christian D; Garde, Sebastian; Knaup, Petra

    2010-01-01

    Clinical trials are of high importance for medical progress. But even though more and more clinical data is available in electronic patient records (EPRs) and more and more electronic data capture (EDC) systems are used in trials, there is still a gap which makes EPR / EDC interoperability difficult and hampers secondary use of medical routine data. The openEHR architecture for Electronic Health Records is based on a two level modeling approach which makes use of 'archetypes'. We want to analyze whether archetypes can help to bridge this gap by building an integrated EPR / EDC system based on openEHR archetypes. We used the 'openEHR Reference Framework and Application' (Opereffa) and existing archetypes for medical data. Furthermore, we developed dedicated archetypes to document study meta data. We developed a first prototype implementation of an archetype based integrated EPR / EDC system. Next steps will be the evaluation of an extended prototype in a real clinical trial scenario. Opereffa was a good starting point for our work. OpenEHR archetypes proved useful for secondary use of health data.

  18. The developmental/emergent model of archetype, its implications and its application to shamanism.

    PubMed

    Merchant, John

    2006-02-01

    This paper addresses the ongoing debate in the JAP to do with archetype theory and supports an emergent/developmental model which sees archetypal imagery as an emergent phenomenon arising out of neural bio-structures laid down in early infant life as a result of developmental experience. This model is supported by the current findings of those developmental biologists who adhere to Developmental Systems Theory. The themes of Developmental Systems Theory are examined and corroborative parallels are drawn with the model. A number of implications follows: the model has substantial explanatory power and leads to a new perspective on innatism; it implies an archetype-environment nexus; it collapses the nature-nurture debate in relation to archetype theory; it collapses the 'sacred heritage' approach to archetypes and it removes the conceptual division between the collective and personal unconscious. This developmental/emergent perspective is then applied to the shaman archetype, using ethnographic records of the Sakha (Yakut) Siberian tribe. The material supports the hypothesis that the shamanic complex is laid down in early infancy by a combination of events which cause emotional ruptures in the mother-infant dyad. Siberian shamanism is then understood to arise out of developmental experience and not from the constellation of an autochthonous archetype.

  19. The archetype-genome exemplar in molecular dynamics and continuum mechanics

    NASA Astrophysics Data System (ADS)

    Greene, M. Steven; Li, Ying; Chen, Wei; Liu, Wing Kam

    2014-04-01

    We argue that mechanics and physics of solids rely on a fundamental exemplar: the apparent properties of a system depend on the building blocks that comprise it. Building blocks are referred to as archetypes and apparent system properties as the system genome. Three entities are of importance: the archetype properties, the conformation of archetypes, and the properties of interactions activated by that conformation. The combination of these entities into the system genome is called assembly. To show the utility of the archetype-genome exemplar, this work presents the mathematical ingredients and computational implementation of theories in solid mechanics that are (1) molecular and (2) continuum manifestations of the assembly process. Both coarse-grained molecular dynamics (CGMD) and the archetype-blending continuum (ABC) theories are formulated then applied to polymer nanocomposites (PNCs) to demonstrate the impact the components of the assembly triplet have on a material genome. CGMD simulations demonstrate the sensitivity of nanocomposite viscosities and diffusion coefficients to polymer chain types (archetype), polymer-nanoparticle interaction potentials (interaction), and the structural configuration (conformation) of dispersed nanoparticles. ABC simulations show the contributions of bulk polymer (archetype) properties, occluded region of bound rubber (interaction) properties, and microstructural binary images (conformation) to predictions of linear damping properties, the Payne effect, and localization/size effects in the same class of PNC material. The paper is light on mathematics. Instead, the focus is on the usefulness of the archetype-genome exemplar to predict system behavior inaccessible to classical theories by transitioning mechanics away from heuristic laws to mechanism-based ones. There are two core contributions of this research: (1) presentation of a fundamental axiom—the archetype-genome exemplar—to guide theory development in computational

  20. Darboux transformation and exact solutions of the integrable Heisenberg ferromagnetic equation with self-consistent potentials

    NASA Astrophysics Data System (ADS)

    Yersultanova, Z. S.; Zhassybayeva, M.; Yesmakhanova, K.; Nugmanova, G.; Myrzakulov, R.

    2016-10-01

    Integrable Heisenberg ferromagnetic equations are an important subclass of integrable systems. The M-XCIX equation is one of a generalizations of the Heisenberg ferromagnetic equation and are integrable. In this paper, the Darboux transformation of the M-XCIX equation is constructed. Using the DT, a 1-soliton solution of the M-XCIX equation is presented.

  1. Towards plug-and-play integration of archetypes into legacy electronic health record systems: the ArchiMed experience

    PubMed Central

    2013-01-01

    Background The dual model approach represents a promising solution for achieving semantically interoperable standardized electronic health record (EHR) exchange. Its acceptance, however, will depend on the effort required for integrating archetypes into legacy EHR systems. Methods We propose a corresponding approach that: (a) automatically generates entry forms in legacy EHR systems from archetypes; and (b) allows the immediate export of EHR documents that are recorded via the generated forms and stored in the EHR systems’ internal format as standardized and archetype-compliant EHR extracts. As a prerequisite for applying our approach, we define a set of basic requirements for the EHR systems. Results We tested our approach with an EHR system called ArchiMed and were able to successfully integrate 15 archetypes from a test set of 27. For 12 archetypes, the form generation failed owing to a particular type of complex structure (multiple repeating subnodes), which was prescribed by the archetypes but not supported by ArchiMed’s data model. Conclusions Our experiences show that archetypes should be customized based on the planned application scenario before their integration. This would allow problematic structures to be dissolved and irrelevant optional archetype nodes to be removed. For customization of archetypes, openEHR templates or specialized archetypes may be employed. Gaps in the data types or terminological features supported by an EHR system will often not preclude integration of the relevant archetypes. More work needs to be done on the usability of the generated forms. PMID:23339403

  2. Bismuth pyrochlore-based thin films for dielectric energy storage

    NASA Astrophysics Data System (ADS)

    Michael, Elizabeth K.

    The drive towards the miniaturization of electronic devices has created a need for dielectric materials with large energy storage densities. These materials, which are used in capacitors, are a critical component in many electrical systems. Here, the development of dielectric energy storage materials for pulsed power applications, which require materials with the ability to accumulate a large amount of energy and then deliver it to the system rapidly, is explored. The amount of electrostatic energy that can be stored by a material is a function of the induced polarization and the dielectric breakdown strength of the material. An ideal energy storage dielectric would possess a high relative permittivity, high dielectric breakdown strength, and low loss tangent under high applied electric fields. The bismuth pyrochlores are a compositionally tunable family of materials that meet these requirements. Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate, were fabricated using a novel solution chemistry based upon the Pechini method. This solution preparation is advantageous because it avoids the use of teratogenic solvents, such as 2-methoxyethanol. Crystalline films fabricated using this solution chemistry had very small grains that were approximately 27 nm in lateral size and 35 nm through the film thickness. Impedance measurements found that the resistivity of the grain boundaries was two orders of magnitude higher than the resistivity of the grain interior. The presence of many resistive grain boundaries impeded conduction through the films, resulting in high breakdown strengths for these materials. In addition to high breakdown strengths, this family of materials exhibited moderate relative permittivities of between 55 +/- 2 and 145 +/- 5, for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 +/- 0.0001. Increases in the concentration of the tantalum

  3. Quantum correlations and coherence in spin-1 Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Malvezzi, A. L.; Karpat, G.; ćakmak, B.; Fanchini, F. F.; Debarba, T.; Vianna, R. O.

    2016-05-01

    We explore quantum and classical correlations along with coherence in the ground states of spin-1 Heisenberg chains, namely the one-dimensional XXZ model and the one-dimensional bilinear biquadratic model, with the techniques of density matrix renormalization group theory. Exploiting the tools of quantum information theory, that is, by studying quantum discord, quantum mutual information, and three recently introduced coherence measures in the reduced density matrix of two nearest neighbor spins in the bulk, we investigate the quantum phase transitions and special symmetry points in these models. We point out the relative strengths and weaknesses of correlation and coherence measures as figures of merit to witness the quantum phase transitions and symmetry points in the considered spin-1 Heisenberg chains. In particular, we demonstrate that, as none of the studied measures can detect the infinite-order Kosterlitz-Thouless transition in the XXZ model, they appear to be able to signal the existence of the same type of transition in the biliear biquadratic model. However, we argue that what is actually detected by the measures here is the SU(3) symmetry point of the model rather than the infinite-order quantum phase transition. Moreover, we show in the XXZ model that examining even single site coherence can be sufficient to spotlight the second-order phase transition and the SU(2) symmetry point.

  4. Transmission electron microscopic study of pyrochlore to defect-fluorite transition in rare-earth pyrohafnates

    SciTech Connect

    Karthik, Chinnathambi; Anderson, Thomas J.; Gout, Delphine; Ubic, Rick

    2012-10-15

    A structural transition in rare earth pyrohafnates, Ln{sub 2}Hf{sub 2}O{sub 7} (Ln=Y, La, Pr, Nd, Tb, Dy, Yb and Lu), has been identified. Neutron diffraction showed that the structure transforms from well-ordered pyrochloric to fully fluoritic through the lanthanide series from La to Lu with a corresponding increase in the position parameter x of the 48f (Fd3{sup Macron }m) oxygen site from 0.330 to 0.375. As evidenced by the selected area electron diffraction, La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} exhibited a well-ordered pyrocholoric structure with the presence of intense superlattice spots, which became weak and diffuse (in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}) before disappearing completely as the series progressed towards the Lu end. High resolution electron microscopic studies showed the breakdown of the pyrochlore ordering in the form of antiphase domains resulting in diffused smoke-like superlattice spots in the case of Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. - Graphical abstract: Transmission electron microscopic studies showed the ordered pyrochlore to defect fluorite transition in rare-earth pyrohafnates to occur via the formation of anti-phase domains to start with. Highlights: Black-Right-Pointing-Pointer Pyrochlore to fluorite structural transition in rare earth pyrohafnates. Black-Right-Pointing-Pointer La{sub 2}Hf{sub 2}O{sub 7}, Pr{sub 2}Hf{sub 2}O{sub 7} and Nd{sub 2}Hf{sub 2}O{sub 7} showed well ordered pyrochlore structure. Black-Right-Pointing-Pointer Short range ordering in Dy{sub 2}Hf{sub 2}O{sub 7} and Tb{sub 2}Hf{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Break down of pyrochlore ordering due to antiphase boundaries. Black-Right-Pointing-Pointer Rest of the series showed fluoritic structure.

  5. Symbol/Meaning paired-associate recall: an "archetypal memory" advantage?

    PubMed

    Sotirova-Kohli, Milena; Opwis, Klaus; Roesler, Christian; Smith, Steven M; Rosen, David H; Vaid, Jyotsna; Djonov, Valentin

    2013-12-01

    The theory of the archetypes and the hypothesis of the collective unconscious are two of the central characteristics of analytical psychology. These provoke, however, varying reactions among academic psychologists. Empirical studies which test these hypotheses are rare. Rosen, Smith, Huston and Gonzales proposed a cognitive psychological experimental paradigm to investigate the nature of archetypes and the collective unconscious as archetypal (evolutionary) memory. In this article we report the results of a cross-cultural replication of Rosen et al. conducted in the German-speaking part of Switzerland. In short, this experiment corroborated previous findings by Rosen et al., based on English speakers, and demonstrated a recall advantage for archetypal symbol meaning pairs vs. other symbol/meaning pairings. The fact that the same pattern of results was observed across two different cultures and languages makes it less likely that they are attributable to a specific cultural or linguistic context. PMID:25379255

  6. Symbol/Meaning Paired-Associate Recall: An “Archetypal Memory” Advantage?

    PubMed Central

    Sotirova-Kohli, Milena; Opwis, Klaus; Roesler, Christian; Smith, Steven M.; Rosen, David H.; Vaid, Jyotsna; Djonov, Valentin

    2013-01-01

    The theory of the archetypes and the hypothesis of the collective unconscious are two of the central characteristics of analytical psychology. These provoke, however, varying reactions among academic psychologists. Empirical studies which test these hypotheses are rare. Rosen, Smith, Huston and Gonzales proposed a cognitive psychological experimental paradigm to investigate the nature of archetypes and the collective unconscious as archetypal (evolutionary) memory. In this article we report the results of a cross-cultural replication of Rosen et al. conducted in the German-speaking part of Switzerland. In short, this experiment corroborated previous findings by Rosen et al., based on English speakers, and demonstrated a recall advantage for archetypal symbol meaning pairs vs. other symbol/meaning pairings. The fact that the same pattern of results was observed across two different cultures and languages makes it less likely that they are attributable to a specific cultural or linguistic context. PMID:25379255

  7. A model-driven approach for representing clinical archetypes for Semantic Web environments.

    PubMed

    Martínez-Costa, Catalina; Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás; Maldonado, José Alberto

    2009-02-01

    The life-long clinical information of any person supported by electronic means configures his Electronic Health Record (EHR). This information is usually distributed among several independent and heterogeneous systems that may be syntactically or semantically incompatible. There are currently different standards for representing and exchanging EHR information among different systems. In advanced EHR approaches, clinical information is represented by means of archetypes. Most of these approaches use the Archetype Definition Language (ADL) to specify archetypes. However, ADL has some drawbacks when attempting to perform semantic activities in Semantic Web environments. In this work, Semantic Web technologies are used to specify clinical archetypes for advanced EHR architectures. The advantages of using the Ontology Web Language (OWL) instead of ADL are described and discussed in this work. Moreover, a solution combining Semantic Web and Model-driven Engineering technologies is proposed to transform ADL into OWL for the CEN EN13606 EHR architecture.

  8. Semantic Interoperable Electronic Patient Records: The Unfolding of Consensus based Archetypes.

    PubMed

    Pedersen, Rune; Wynn, Rolf; Ellingsen, Gunnar

    2015-01-01

    This paper is a status report from a large-scale openEHR-based EPR project from the North Norway Regional Health Authority encouraged by the unfolding of a national repository for openEHR archetypes. Clinicians need to engage in, and be responsible for the production of archetypes. The consensus processes have so far been challenged by a low number of active clinicians, a lack of critical specialties to reach consensus, and a cumbersome review process (3 or 4 review rounds) for each archetype. The goal is to have several clinicians from each specialty as a backup if one is hampered to participate. Archetypes and their importance for structured data and sharing of information has to become more visible for the clinicians through more sharpened information practice. PMID:25991124

  9. Case Study: Applying OpenEHR Archetypes to a Clinical Data Repository in a Chinese Hospital.

    PubMed

    Min, Lingtong; Wang, Li; Lu, Xudong; Duan, Huilong

    2015-01-01

    openEHR is a flexible and scalable modeling methodology for clinical information and has been widely adopted in Europe and Australia. Due to the reasons of differences in clinical process and management, there are few research projects involving openEHR in China. To investigate the feasibility of openEHR methodology for clinical information modelling in China, this paper carries out a case study to apply openEHR archetypes to Clinical Data Repository (CDR) in a Chinese hospital. The results show that a set of 26 archetypes are found to cover all the concepts used in the CDR. Of all these, 9 (34.6%) are reused without change, 10 are modified and/or extended, and 7 are newly defined. The reasons for modification, extension and newly definition have been discussed, including granularity of archetype, metadata-level versus data-level modelling, and the representation of relationships between archetypes. PMID:26262040

  10. Validation of the openEHR archetype library by using OWL reasoning.

    PubMed

    Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás

    2011-01-01

    Electronic Health Record architectures based on the dual model architecture use archetypes for representing clinical knowledge. Therefore, ensuring their correctness and consistency is a fundamental research goal. In this work, we explore how an approach based on OWL technologies can be used for such purpose. This method has been applied to the openEHR archetype repository, which is the largest available one nowadays. The results of this validation are also reported in this study.

  11. Fractionalized charge excitations in a spin liquid on partially filled pyrochlore lattices.

    PubMed

    Chen, Gang; Kee, Hae-Young; Kim, Yong Baek

    2014-11-01

    We study the Mott transition from a metal to cluster Mott insulators in the 1/4- and 1/8-filled pyrochlore lattice systems [corrected]. It is shown that such Mott transitions can arise due to charge localization in clusters or in tetrahedron units, driven by the nearest-neighbor repulsive interaction. The resulting cluster Mott insulator is a quantum spin liquid with a spinon Fermi surface, but at the same time a novel fractionalized charge liquid with charge excitations carrying half the electron charge. There exist two emergent U(1) gauge fields or "photons" that mediate interactions between spinons and charge excitations, and between fractionalized charge excitations themselves, respectively. In particular, it is suggested that the emergent photons associated with the fractionalized charge excitations can be measured in x-ray scattering experiments. Various other experimental signatures of the exotic cluster Mott insulator are discussed in light of candidate materials with partially filled bands on the pyrochlore lattice.

  12. All-in-all-out magnetic domain wall conduction in a pyrochlore iridate heterointerface

    NASA Astrophysics Data System (ADS)

    Fujita, T. C.; Uchida, M.; Kozuka, Y.; Sano, W.; Tsukazaki, A.; Arima, T.; Kawasaki, M.

    2016-02-01

    Pyrochlore oxides possessing "all-in-all-out" spin ordering have attracted burgeoning interest as a rich ground of emergent states. This ordering has two distinct types of magnetic domains (all-in-all-out or all-out-all-in) with broken time-reversal symmetry, and a nontrivial metallic surface state has been theoretically demonstrated to appear at their domain wall. Here, we report on the observation of this metallic conduction at the single all-in-all-out/all-out-all-in magnetic domain wall formed at the heterointerface of two pyrochlore iridates. By utilizing the different magnetoresponses of them with different lanthanide ions, the domain wall is controllably inserted at the heterointerface, the surface state being detected as an anomalous conduction enhancement with a ferroic hysteresis. Our establishment paves the way for further investigation and manipulation of this new type of surface transport.

  13. Candidate Quantum Spin Liquid in the Ce3+ Pyrochlore Stannate Ce2Sn2O7.

    PubMed

    Sibille, Romain; Lhotel, Elsa; Pomjakushin, Vladimir; Baines, Chris; Fennell, Tom; Kenzelmann, Michel

    2015-08-28

    We report the low-temperature magnetic properties of Ce2Sn2O7, a rare-earth pyrochlore. Our susceptibility and magnetization measurements show that due to the thermal isolation of a Kramers doublet ground state, Ce2Sn2O7 has Ising-like magnetic moments of ∼1.18  μ_{B}. The magnetic moments are confined to the local trigonal axes, as in a spin ice, but the exchange interactions are antiferromagnetic. Below 1 K, the system enters a regime with antiferromagnetic correlations. In contrast to predictions for classical ⟨111⟩-Ising spins on the pyrochlore lattice, there is no sign of long-range ordering down to 0.02 K. Our results suggest that Ce2Sn2O7 features an antiferromagnetic liquid ground state with strong quantum fluctuations. PMID:26371677

  14. First-principles insights into f magnetism: A case study on some magnetic pyrochlores

    NASA Astrophysics Data System (ADS)

    Deilynazar, Najmeh; Khorasani, Elham; Alaei, Mojtaba; Javad Hashemifar, S.

    2015-11-01

    First-principles calculations are performed to investigate f magnetism in A2Ti2O7 (A=Eu, Gd, Tb, Dy, Ho, Er, Yb) magnetic pyrochlore oxides. The Hubbard U parameter and the relativistic spin orbit correction are applied for a more accurate description of the electronic structure of the systems. It is argued that the main obstacle for the first-principles study of these systems is the multi-minima solutions of their electronic configuration. Among the studied pyrochlores, Gd2Ti2O7 shows the least multi-minima problem. The crystal electric field theory is applied for phenomenological comparison of the calculated spin and orbital moments with the experimental data.

  15. Exotic topological states near a quantum metal-insulator transition in pyrochlore iridates

    NASA Astrophysics Data System (ADS)

    Tian, Zhaoming

    Pyrochlore iridates have attracted great interest as prime candidates that may host topologically nontrivial states, spin ice ordering and quantum spin liquid states, in particular through the interplay between different degrees of freedom, such as local moments and mobile electrons. Based on our extensive study using our high quality single crystals, we will discuss such examples, i.e. chiral spin liquid in a quadratic band touching state, Weyl semimetallic state and chiral domain wall transport nearby a quantum insulator-semimetal transition in pyrochlore iridates. This work is based on the collaboration with Nakatsuji Satoru, Kohama Yoshimitsu, Tomita Takahiro, Kindo Koichi, Jun J. Ishikawa, Balents Leon, Ishizuka Hiroaki, Timothy H. Hsieh. ZM. Tian was supported by JSPS Postdoctoral Fellowship (No.P1402).

  16. Archetype JC virus efficiently propagates in kidney-derived cells stably expressing HIV-1 Tat.

    PubMed

    Nukuzuma, Souichi; Kameoka, Masanori; Sugiura, Shigeki; Nakamichi, Kazuo; Nukuzuma, Chiyoko; Miyoshi, Isao; Takegami, Tsutomu

    2009-11-01

    Pathogenic JCV with rearranged regulatory regions (PML-type) causes PML, a demyelinating disease, in the brains of immunocompromised patients. On the other hand, archetype JCV persistently infecting the kidney is thought to be converted to PML-type virus during JCV replication in the infected host under immunosuppressed conditions. In addition, Tat protein, encoded by HIV-1, markedly enhances the expression of a reporter gene under control of the JCV late promoter. In order to examine the influence of Tat on JCV propagation, we used kidney-derived COS-7 cells, which only permit archetype JCV, and established COS-tat cells, which express HIV-1 Tat stably. We found that the extent of archetype JCV propagation in COS-tat cells is significantly greater than in COS-7 cells. On the other hand, COS-7 cells express SV40 T antigen, which is a strong stimulator of archetype JCV replication. The expression of SV40 T antigen was enhanced by HIV-1 Tat slightly according to real-time RT-PCR, this was not closely related to JCV replication in COS-tat cells. The efficiency of JCV propagation depended on the extent of expression of functional Tat. To our knowledge, this is the first report of increased production of archetype JCV in a culture system using cell lines stably expressing HIV-1 Tat. We propose here that COS-tat cells are a useful tool for studying the role of Tat in archetype JCV replication in the development of PML.

  17. Functional comparison of PML-type and archetype strains of JC virus.

    PubMed

    Sock, E; Renner, K; Feist, D; Leger, H; Wegner, M

    1996-03-01

    Isolates of the human polyomavirus JC can be grouped as either PML-type or archetype strains primarily on the basis of divergence in their regulatory regions. Only PML-type viruses have so far been found to be associated with the human demyelinating disease progressive multifocal leukoencephalopathy. Here we have compared the functional properties of archetype and PML-type regulatory regions with regard to DNA replication and viral gene expression. No significant differences could be detected between archetype and PML-type regions in their ability to direct episomal DNA replication in the presence of JC virus T antigen. When viral gene expression was examined, early- and late-gene promoters from all PML-type strains exhibited a significantly higher activity in glial than in nonglial cells. Surprisingly, archetype strain promoters were also preferentially active in glial cells, although this effect was less pronounced than in PML-type strains. Furthermore, all promoters from archetype strains reacted to the presence of viral T antigen or the glial transcription factor Tst-1/Oct6 in a manner similar to the promoters of the PML-type viral strain Mad-1. Interestingly, T antigen and Tst-1/Oct6 were found to function in a species-specific and cell-type-specific manner, respectively. We concluded from our experiments that the differences in the regulatory regions cannot account for the different biology of archetype and PML-type viral strains.

  18. Insights into dynamic processes of cations in pyrochlores and other complex oxides

    DOE PAGESBeta

    Uberuaga, Blas Pedro; Perriot, Romain

    2015-08-26

    Complex oxides are critical components of many key technologies, from solid oxide fuel cells and superionics to inert matrix fuels and nuclear waste forms. In many cases, understanding mass transport is important for predicting performance and, thus, extensive effort has been devoted to understanding mass transport in these materials. However, most work has focused on the behavior of oxygen while cation transport has received relatively little attention, even though cation diffusion is responsible for many phenomena, including sintering, radiation damage evolution, and deformation processes. Here, we use accelerated molecular dynamics simulations to examine the kinetics of cation defects in onemore » class of complex oxides, A₂B₂O₇ pyrochlore. In some pyrochlore chemistries, B cation defects are kinetically unstable, transforming to A cation defects and antisites at rates faster than they can diffuse. When this occurs, transport of B cations occurs through defect processes on the A sublattice. Further, these A cation defects, either interstitials or vacancies, can interact with antisite disorder, reordering the material locally, though this process is much more efficient for interstitials than vacancies. Whether this behavior occurs in a given pyrochlore depends on the A and B chemistry. Pyrochlores with a smaller ratio of cation radii exhibit this complex behavior, while those with larger ratios exhibit direct migration of B interstitials. Similar behavior has been reported in other complex oxides such as spinels and perovskites, suggesting that this coupling of transport between the A and B cation sublattices, while not universal, occurs in many complex oxide.« less

  19. Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

    SciTech Connect

    Han, Sang-Wook; Gardner, Jason S.; Booth, Corwin H.

    2004-06-14

    Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb{sub 2}Ti{sub 2}O{sub 7}. However, previous structural studies indicated that Tb{sub 2}Ti{sub 2}O{sub 7} is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb{sub 2}Ti{sub 2}O{sub 7} is well ordered with no structural transitions between 4.5 and 600 K. In particular, mean-squared displacements (u{sup 2}'s) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L{sub III} and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb{sub 2}Ti{sub 2}O{sub 7} has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures.

  20. Characterization of the heavy metal pyrochlore lattice superconductor CaIr2.

    PubMed

    Haldolaarachchige, Neel; Gibson, Quinn; Schoop, Leslie M; Luo, Huixia; Cava, R J

    2015-05-13

    We report the electronic properties of the cubic laves phase superconductor CaIr2(Tc = 5.8 K), in which the Ir atoms have a pyrochlore lattice. The estimated superconducting parameters obtained from magnetization and specific heat measurements indicate that CaIr2 is a weakly coupled BCS superconductor. Electronic band structure calculations show that the Ir d-states are dominant at the Fermi level, creating a complex Fermi surface that is impacted substantially by spin-orbit coupling.

  1. Coulomb Liquid Phases of Bosonic Cluster Mott Insulators on a Pyrochlore Lattice.

    PubMed

    Lv, Jian-Ping; Chen, Gang; Deng, Youjin; Meng, Zi Yang

    2015-07-17

    Employing large-scale quantum Monte Carlo simulations, we reveal the full phase diagram of the extended Hubbard model of hard-core bosons on the pyrochlore lattice with partial fillings. When the intersite repulsion is dominant, the system is in a cluster Mott insulator phase with an integer number of bosons localized inside the tetrahedral units of the pyrochlore lattice. We show that the full phase diagram contains three cluster Mott insulator phases with 1/4, 1/2, and 3/4 boson fillings, respectively. We further demonstrate that all three cluster Mott insulators are Coulomb liquid phases and its low-energy property is described by the emergent compact U(1) quantum electrodynamics. In addition to measuring the specific heat and entropy of the cluster Mott insulators, we investigate the correlation function of the emergent electric field and verify it is consistent with the compact U(1) quantum electrodynamics description. Our result sheds light on the magnetic properties of various pyrochlore systems, as well as the charge physics of the cluster magnets.

  2. Thermal recrystallization of alpha-recoil damaged minerals of the pyrochlore structure type

    SciTech Connect

    Lumpkin, G.R.; Ewing, R.C.; Foltyn, E.M.

    1985-10-01

    Thermal recrystallization effects (heat of recrystallization and identification of phases formed), have been determined for naturally occurring members of the pyrochlore group which have received alpha doses of up to 4 X 10{sup 16} alphas/mg. The heats of recrystallization, E{sub t}, range from 125 to 210 J/g. Release of energy decreases as a function of crystallinity (estimated on the basis of the intensity of x-ray diffraction maxima), with the fully-metamict samples approaching 210 J/g. Lower measured values (40-125 J/g) are the result of alteration of the pyrochlores. Other metamict, complex oxides with stoichiometries of ABO{sub 4} and AB{sub 2}O{sub 6} have lower heats of recrystallization (40-85 J/g), and are easily distinguished from pyrochlore group minerals. Activation energies of recrystallization, E{sub a}, range between values of 0.29 to 0.97 eV, less than those measured for Pu-doped, synthetic zirconolites.

  3. Multistage symmetry breaking in the breathing pyrochlore lattice Li(Ga ,In )Cr 4O8

    NASA Astrophysics Data System (ADS)

    Lee, S.; Do, S.-H.; Lee, W.-J.; Choi, Y. S.; Lee, M.; Choi, E. S.; Reyes, A. P.; Kuhns, P. L.; Ozarowski, A.; Choi, K.-Y.

    2016-05-01

    We present magnetic susceptibility, dielectric constant, high-frequency electron spin resonance, 7Li nuclear magnetic resonance, and zero-field muon spin relaxation measurements of LiACr4O8 (A =Ga , In), towards realizing a breathing pyrochlore lattice. Unlike the uniform pyrochlore ZnCr2O4 lattice, both the In and the Ga compounds feature two-stage symmetry breaking: a magnetostructural phase transition with subsequent antiferromagnetic ordering. We find a disparate symmetry breaking process between the In and the Ga compounds, having different degrees of bond alternation. Our data reveal that the Ga compound with moderate bond alternation shows the concomitant structural and magnetic transition at TS=15.2 K, followed by the magnetic ordering at Tm=12.9 K. In contrast, the In compound with strong bond alternation undergoes a thermal crossover at T*≈20.1 K from a tetramer singlet to a dimer singlet or a correlated paramagnet with a separate weak magnetostructural transition at TS=17.6 K and the second antiferromagnetic ordering at Tm=13.7 K. This suggests that the magnetic phases and correlations of the breathing pyrochlore lattice can be determined from the competition between bond alternation and spin-lattice coupling, thus stabilizing long-range magnetic ordering against a nonmagnetic singlet.

  4. Coulomb Liquid Phases of Bosonic Cluster Mott Insulators on a Pyrochlore Lattice.

    PubMed

    Lv, Jian-Ping; Chen, Gang; Deng, Youjin; Meng, Zi Yang

    2015-07-17

    Employing large-scale quantum Monte Carlo simulations, we reveal the full phase diagram of the extended Hubbard model of hard-core bosons on the pyrochlore lattice with partial fillings. When the intersite repulsion is dominant, the system is in a cluster Mott insulator phase with an integer number of bosons localized inside the tetrahedral units of the pyrochlore lattice. We show that the full phase diagram contains three cluster Mott insulator phases with 1/4, 1/2, and 3/4 boson fillings, respectively. We further demonstrate that all three cluster Mott insulators are Coulomb liquid phases and its low-energy property is described by the emergent compact U(1) quantum electrodynamics. In addition to measuring the specific heat and entropy of the cluster Mott insulators, we investigate the correlation function of the emergent electric field and verify it is consistent with the compact U(1) quantum electrodynamics description. Our result sheds light on the magnetic properties of various pyrochlore systems, as well as the charge physics of the cluster magnets. PMID:26230823

  5. Effects of Doping on Thermal Conductivity of Pyrochlore Oxides for Advanced Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

    2006-01-01

    Pyrochlore oxides of general composition, A2B2O7, where A is a 3(+) cation (La to Lu) and B is a 4(+) cation (Zr, Hf, Ti, etc.) have high melting point, relatively high coefficient of thermal expansion, and low thermal conductivity which make them suitable for applications as high-temperature thermal barrier coatings. The effect of doping at the A site on the thermal conductivity of a pyrochlore oxide La2Zr2O7, has been investigated. Oxide powders of various compositions La2Zr2O7, La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 were synthesized by the citric acid sol-gel method. These powders were hot pressed into discs and used for thermal conductivity measurements using a steady-state laser heat flux test technique. The rare earth oxide doped pyrochlores La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 had lower thermal conductivity than the un-doped La2Zr2O7. The Gd2O3 and Yb2O3 co-doped composition showed the lowest thermal conductivity.

  6. Recent μSR Studies of Insulating Rare-Earth Pyrochlore Magnets

    NASA Astrophysics Data System (ADS)

    Dalmas de Réotier, Pierre; Maisuradze, Alexander; Yaouanc, Alain

    2016-09-01

    We review recent muon spin rotation and relaxation (μSR) studies performed on insulating magnetic systems crystallizing in the pyrochlore structure and for which the only magnetic species are rare-earth ions. Different points are discussed: attempts to measure directly the magnetic charge of the monopoles in classical spin-ice systems, the frequency shift of Tb2Ti2O7 at 20 mK which is at variance with expectation for a quantum spin-ice system, and the detection of unexpected short-range magnetic correlations in the magnetically ordered state of Yb2Ti2O7, Yb2Sn2O7, and Er2Ti2O7. An explanation for the ubiquitous persistent spin dynamics is given in terms of spin loops. Their description requires to go beyond mean-field, i.e., at least Gaussian fluctuations have to be taken into account. While in the magnetically ordered state a spontaneous field is detected for some systems, such as Nd2Sn2O7, it is absent for others, such as Yb2Sn2O7. A theoretical work suggests this feature to be related to the magnetic structure adopted by the magnetic moments. A μSR work on praseodymium-based pyrochlore compounds is also discussed. Normal rare-earth spinel systems for which the magnetic ions form a network of corner sharing regular tetrahedra as in the pyrochlores are finally mentioned.

  7. Theoretical investigation of structural, energetic and electronic properties of titanate pyrochlores

    NASA Astrophysics Data System (ADS)

    Xiao, H. Y.; Wang, L. M.; Zu, X. T.; Lian, Jie; Ewing, Rodney C.

    2007-08-01

    Ab initio total energy calculations using the plane-wave pseudopotential method based on density functional theory were carried out to investigate the structural, energetic and electronic properties of A2Ti2O7 (A = La, Gd and Yb) pyrochlores. It turned out that the formation energies of antisite defects are not linearly dependent on the ratio of the cation radii, and, for the three compositions, the cation antisite formation energy is largest for Gd2Ti2O7 pyrochlore. It was indicated that Gd2Ti2O7 compound is the least likely to form defect fluorite structure, which gives rise to the least resistance to radiation-induced amorphization. DOS analysis showed that stronger interaction exists in the Gd2Ti2O7 compound, and its electronic structure is very different from that of La2Ti2O7 and Yb2Ti2O7. Our calculations suggested that the electronic structure of the A cation and bond type should be taken into account when explaining the response behavior of A2Ti2O7 (A = La, Gd, Yb) pyrochlores to ion irradiation-induced amorphization.

  8. Emergence of magnetic order in ultra-thin pyrochlore iridate films

    NASA Astrophysics Data System (ADS)

    Cheema, Suraj; Serrao, Claudy; Mundy, Julia; Patankar, Shreyas; Birgeneau, Robert; Orenstein, Joseph; Salahuddin, Sayeef; Ramesh, Ramamoorthy

    We report on thickness-dependent magnetotransport in (111) - oriented Pb2Ir2O7-x (Pb227) epitaxial thin films. For thicknesses greater than 4 nm, the magnetoresistance (MR) of metallic Pb227 is positive, linear and non-saturated up to 14 T. Meanwhile at 4 nm, the conduction turns nonmetallic and the MR becomes negative and asymmetric upon field-cooling; such traits are reminiscent of all-in-all-out (AIAO) magnetic order in the insulating pyrochlore iridates. Hysteretic low-field MR dips and trained-untrained resistivity bifurcations suggest the presence of magnetic conducting domain walls within the chiral AIAO spin structure. Beyond just AIAO order, angular-dependent MR indicates a magnetic phase space hosting 2-in-2-out (2I2O) spin ice order. Such anomalous magnetotransport calls for re-evaluation of the pyrochlore iridate phase diagram, as epitaxially strained Pb227 exhibits traits reminiscent of both the insulating magnetic and metallic spin-liquid members. Furthermore, these results open avenues for realizing topological phase predictions in (111) - oriented pyrochlore slabs of kagome-triangular iridate heterostructures. This work is supported by the Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC02-05CH11231.

  9. Anomalous lattice parameter increase in alkali earth aluminium substituted tungsten defect pyrochlores

    SciTech Connect

    Thorogood, Gordon J. Kennedy, Brendan J.; Peterson, Vanessa K.; Elcombe, Margaret M.; Kearley, Gordon J.; Hanna, John V.; Luca, Vittorio

    2009-03-15

    The structures of the defect pyrochlores AAl{sub 0.33}W{sub 1.67}O{sub 6} where A=K, Rb or Cs have been investigated using X-ray and neutron powder diffraction methods as well as the ab initio modelling program VASP. The three cubic pyrochlores exhibit a non-linear increase in lattice parameter with respect to ionic radius of the A cation as a consequence of displacive disorder of the A-type cations. Solid state {sup 27}Al MAS NMR studies of this pyrochlore system reveal shifts in the {delta}{approx}21-22 ppm range that are indicative of pseudo-5 coordinate Al environments and emanate from distorted Al octahedral with one abnormally long Al-O bond. Solid state {sup 39}K, {sup 85}Rb, {sup 87}Rb and {sup 133}Cs MAS and static NMR studies reflect the local cation disorder demonstrated in the structural studies. - Graphical abstract: Diagram showing general disorder of K cations in KAl{sub 0.33}W{sub 1.67}O{sub 6}.

  10. Pyrochlores from the Lueshe carbonatite complex (Democratic Republic of Congo): a geochemical record of different alteration stages

    NASA Astrophysics Data System (ADS)

    Nasraoui, M.; Bilal, E.

    2000-04-01

    Magmatic pyrochlores from the Lueshe syenite-carbonatite complex from the northeastern part of Democratic Republic of Congo (ex-Zaı̈re) are characterized by Ta/Nb ratios in an increasing order from pyroxenite, calcite-carbonatite (sövite), silicate xenoliths (nodules) to syenite. Substitutions involving Nb, Ta, Ti and REE have been precisely described. Hydrothermal alteration of Lueshe pyrochlore involves the substitution of Na ++F -=VA+VY and Ca+O=VA+VY (VA=A-site vacancy and VY=Y-site vacancy). In calcite carbonatite, hydrothermal alteration of pyrochlore took place during and after the precipitation of ancylite-(Ce), strontianite, celestite, baryte and fayalite according to a fluid composition of relatively low pH, aNa +, aCa 2+ and aHF, and high aSr 2+ and aLREE 3+. The supergene alteration is characterized by complete leaching of Na, Ca and F and partial incorporation of K, Ba, Sr and Ce resulting in the formation of kali-, bario-, strontio- and ceriopyrochlore respectively. The Na-poor pyrochlore may be an intermediate variety corresponding to an alteration stage between the hydrothermal and weathered pyrochlores. The IR spectroscopic study has indicated that the weathered pyrochlore is a hydrated variety containing two bands of OH vibration modes at 3413 and 1630 cm -1. During hydrothermal and supergene alterations, the cations at B-site remain relatively constant. The variable chemical compositions of the pyrochlores from the Lueshe complex represent geochemical memories of the different alteration conditions including the variation in the oxidation-reduction environment.

  11. Cyprinid Herpesvirus 3: An Archetype of Fish Alloherpesviruses.

    PubMed

    Boutier, Maxime; Ronsmans, Maygane; Rakus, Krzysztof; Jazowiecka-Rakus, Joanna; Vancsok, Catherine; Morvan, Léa; Peñaranda, Ma Michelle D; Stone, David M; Way, Keith; van Beurden, Steven J; Davison, Andrew J; Vanderplasschen, Alain

    2015-01-01

    The order Herpesvirales encompasses viruses that share structural, genetic, and biological properties. However, members of this order infect hosts ranging from molluscs to humans. It is currently divided into three phylogenetically related families. The Alloherpesviridae family contains viruses infecting fish and amphibians. There are 12 alloherpesviruses described to date, 10 of which infect fish. Over the last decade, cyprinid herpesvirus 3 (CyHV-3) infecting common and koi carp has emerged as the archetype of fish alloherpesviruses. Since its first description in the late 1990s, this virus has induced important economic losses in common and koi carp worldwide. It has also had negative environmental implications by affecting wild carp populations. These negative impacts and the importance of the host species have stimulated studies aimed at developing diagnostic and prophylactic tools. Unexpectedly, the data generated by these applied studies have stimulated interest in CyHV-3 as a model for fundamental research. This review intends to provide a complete overview of the knowledge currently available on CyHV-3.

  12. The Health Archetype Language (HAL-42): interface considerations.

    PubMed

    Elkin, Peter L; Froehling, David; Wahner-Roedler, Dietlind; Trusko, Brett; Welsh, Gail; Rosenbloom, S Trent; Speroff, Theodore; Brown, Steven H

    2010-04-01

    In this manuscript we report an evaluation of the reliability of clinical research rules creation by multiple clinicians using the Health Archetype Language (HAL-42) and user interface. HAL-42 is a language which allows real time epidemiological inquiry using automatically derived clinical encodings with any health Ontology. This evaluation used SNOMED CT as the underlying Ontology. The inquiries were performed on a population of 17,731 patients whose 50,000 clinical records have all been fully encoded in SNOMED CT. Four subject matter experts (SMEs) were asked independently to encode and run 10 rules/studies. The inter-rater agreement was 74.8% (p=0.6526) with a Kappa statistic of 0.49217 (p=0.5722). The ten rules were divided into three easy rules, four moderate and three complex rules. There was no significant difference in the SME's agreement when representing easy and complex rules (p=0.6243). We conclude that although the usability of the HAL-42 language is usable enough to achieve reasonable inter-rater reliability, some training will be necessary to reach high levels of reliability for ad hoc queries. We also conclude that SMEs are just as competent to perform complex queries as easy queries of ontologically indexed clinical data.

  13. Quantum spin transistor with a Heisenberg spin chain

    NASA Astrophysics Data System (ADS)

    Marchukov, O. V.; Volosniev, A. G.; Valiente, M.; Petrosyan, D.; Zinner, N. T.

    2016-10-01

    Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements.

  14. Quantum spin transistor with a Heisenberg spin chain

    PubMed Central

    Marchukov, O. V.; Volosniev, A. G.; Valiente, M.; Petrosyan, D.; Zinner, N. T.

    2016-01-01

    Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements. PMID:27721438

  15. Thermal and magnetic quantum discord in Heisenberg models

    SciTech Connect

    Werlang, T.; Rigolin, Gustavo

    2010-04-15

    We investigate how quantum correlations [quantum discord (QD)] of a two-qubit one-dimensional XYZ Heisenberg chain in thermal equilibrium depend on the temperature T of the bath and also on an external magnetic field B. We show that the behavior of thermal QD differs in many unexpected ways from thermal entanglement. For example, we show situations where QD increases with T when entanglement decreases, cases where QD increases with T even in regions with zero entanglement, and that QD signals a quantum phase transition even at finite T. We also show that by properly tuning B or the interaction between the qubits we get nonzero QD for any T and we present an effect not seen for entanglement, the 'regrowth' of thermal QD.

  16. Local Spin Relaxation within the Random Heisenberg Chain

    NASA Astrophysics Data System (ADS)

    Herbrych, J.; Kokalj, J.; Prelovšek, P.

    2013-10-01

    Finite-temperature local dynamical spin correlations Snn(ω) are studied numerically within the random spin-1/2 antiferromagnetic Heisenberg chain. The aim is to explain measured NMR spin-lattice relaxation times in BaCu2(Si0.5Ge0.5)2O7, which is the realization of a random spin chain. In agreement with experiments we find that the distribution of relaxation times within the model shows a very large span similar to the stretched-exponential form. The distribution is strongly reduced with increasing T, but stays finite also in the high-T limit. Anomalous dynamical correlations can be associated with the random singlet concept but not directly with static quantities. Our results also reveal the crucial role of the spin anisotropy (interaction), since the behavior is in contrast with the ones for the XX model, where we do not find any significant T dependence of the distribution.

  17. Fitting magnetic field gradient with Heisenberg-scaling accuracy

    PubMed Central

    Zhang, Yong-Liang; Wang, Huan; Jing, Li; Mu, Liang-Zhu; Fan, Heng

    2014-01-01

    The linear function is possibly the simplest and the most used relation appearing in various areas of our world. A linear relation can be generally determined by the least square linear fitting (LSLF) method using several measured quantities depending on variables. This happens for such as detecting the gradient of a magnetic field. Here, we propose a quantum fitting scheme to estimate the magnetic field gradient with N-atom spins preparing in W state. Our scheme combines the quantum multi-parameter estimation and the least square linear fitting method to achieve the quantum Cramér-Rao bound (QCRB). We show that the estimated quantity achieves the Heisenberg-scaling accuracy. Our scheme of quantum metrology combined with data fitting provides a new method in fast high precision measurements. PMID:25487218

  18. Heisenberg-limited atom clocks based on entangled qubits.

    PubMed

    Kessler, E M; Kómár, P; Bishof, M; Jiang, L; Sørensen, A S; Ye, J; Lukin, M D

    2014-05-16

    We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. Importantly the protocol is designed to work under realistic conditions where the drift of the phase of the laser interrogating the atoms is the main source of decoherence. The simultaneous interrogation of the laser phase with a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the coherent interrogation time beyond the laser noise limit. We compare and merge the new protocol with existing state of the art interrogation schemes, and identify the precise conditions under which entanglement provides an advantage for clock stabilization: it allows a significant gain in the stability for short averaging time.

  19. Werner Heisenberg zum 100. Geburtstag: Pionier der Quantenmechanik

    NASA Astrophysics Data System (ADS)

    Jacobi, Manfred

    2001-11-01

    Werner Heisenberg war eine der prägendsten Gestalten der Physik des 20. Jahrhunderts. Zu seinen wichtigsten Verdiensten gehören die Grundlegung der Quantenmechanik, die Formulierung der Unschärferelationen sowie die Beteiligung an der Ausarbeitung der Kopenhagener Deutung der Quantenmechanik. Darüber hinaus lieferte er Arbeiten von fundamentalem Charakter zur Theorie des Atomkerns, zur kosmischen Strahlung und zur Quantenfeldtheorie. Während des Krieges war er an den Arbeiten des Uranvereins beteiligt, der die Möglichkeit einer Entwicklung von Kernwaffen untersuchte, jedoch über Vorarbeiten zur Reaktorphysik nicht hinauskam. Wegen dieser Tätigkeit wurde er bei Kriegsende für einige Monate in England interniert. Nach seiner Rückkehr widmete er sich vor allem dem Aufbau der Physik in Deutschland, die während der NS-Zeit nahezu ihrer gesamten Substanz beraubt worden war.

  20. 3D Ordering in 2D Quantum Heisenberg Antiferromagnets

    NASA Astrophysics Data System (ADS)

    Landee, C. P.; Woodward, F. M.; Giantsidis, J.; Turnbull, M. M.

    2000-03-01

    The family of 2D quantum Heisenberg antiferromagnets (5-ZAP)_2CuX4 consists of CuX_4^2- dianions packed together in magnetically square layers, interacting through X\\cdotsX contacts (X = Cl, Br). The strength of both the intralayer interaction J and interlayer interaction J^' are controlled by the substituent Z in the 5-position of 5-Z, 2-aminopyridine. The 3D critical temperature TN is a function of the J^'/J ratio and consequently is also subject to control by the Z-substituent. Previously we have reported on the compounds with Z = Cl (5-CAP), and Z = methyl (5-MAP). We have now prepared the isomorphous 5-bromo analogue (5-BAP)_2CuX4 and will discuss the T_N/J ratios for all three compounds in terms of the structural parameters.

  1. The elusive Heisenberg limit in quantum-enhanced metrology.

    PubMed

    Demkowicz-Dobrzański, Rafał; Kołodyński, Jan; Guţă, Mădălin

    2012-01-01

    Quantum precision enhancement is of fundamental importance for the development of advanced metrological optical experiments, such as gravitational wave detection and frequency calibration with atomic clocks. Precision in these experiments is strongly limited by the 1/√N shot noise factor with N being the number of probes (photons, atoms) employed in the experiment. Quantum theory provides tools to overcome the bound by using entangled probes. In an idealized scenario this gives rise to the Heisenberg scaling of precision 1/N. Here we show that when decoherence is taken into account, the maximal possible quantum enhancement in the asymptotic limit of infinite N amounts generically to a constant factor rather than quadratic improvement. We provide efficient and intuitive tools for deriving the bounds based on the geometry of quantum channels and semi-definite programming. We apply these tools to derive bounds for models of decoherence relevant for metrological applications including: depolarization, dephasing, spontaneous emission and photon loss. PMID:22990859

  2. Heisenberg-limited atom clocks based on entangled qubits.

    PubMed

    Kessler, E M; Kómár, P; Bishof, M; Jiang, L; Sørensen, A S; Ye, J; Lukin, M D

    2014-05-16

    We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. Importantly the protocol is designed to work under realistic conditions where the drift of the phase of the laser interrogating the atoms is the main source of decoherence. The simultaneous interrogation of the laser phase with a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the coherent interrogation time beyond the laser noise limit. We compare and merge the new protocol with existing state of the art interrogation schemes, and identify the precise conditions under which entanglement provides an advantage for clock stabilization: it allows a significant gain in the stability for short averaging time. PMID:24877919

  3. Energy dynamics in the Heisenberg-Kitaev spin chain

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Brenig, Wolfram

    2016-06-01

    We study the Heisenberg-Kitaev spin chain in order to uncover the interplay between two qualitatively different integrable points in the physics of heat transport in one dimension. Focusing on high temperatures and using analytical as well as numerical approaches within linear response theory, we explore several directions in parameter space including exchange-coupling ratios, anisotropies, and external magnetic fields. We show the emergence of purely ballistic energy transport at all integrable points, manifest in pronounced Drude weights and low-frequency suppression of regular-conductivity contributions. Moreover, off integrability, we find extended quantum chaotic regions with vanishing Drude weights and well-defined dc conductivities. In the vicinity of the Kitaev point, we observe clear signatures of the topological gap in the response function. This gap coexists with a nonzero Drude weight in the Kitaev chain.

  4. Fractionalized Fermi liquid in a Kondo-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Tsvelik, A. M.

    2016-10-01

    The Kondo-Heisenberg model is used as a controllable tool to demonstrate the existence of a peculiar metallic state with unbroken translational symmetry where the Fermi surface volume is not controlled by the total electron density. I use a nonperturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. In agreement with the general requirements formulated by T. Senthil et al. [Phys. Rev. Lett. 90, 216403 (2003), 10.1103/PhysRevLett.90.216403], the resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations. The system undergoes a phase transition to an ordered phase (charge density wave or superconducting), at the transition temperature which is parametrically small in comparison to the quasiparticle Fermi energy.

  5. Correlation length of the isotropic quantum Heisenberg antiferromagnet

    SciTech Connect

    Cuccoli, A.; Tognetti, V.; Vaia, R.

    1997-04-01

    The quantum Heisenberg antiferromagnet on the square lattice is known to model the magnetic interactions in the copper ion planes of many high-{ital T{sub c}} superconductors and their parent compounds. The thermodynamics of the model is approached by the {ital pure-quantum self-consistent harmonic approximation}, that reduces the quantum problem to the study of an effective classical antiferromagnetic system. The effective exchange, weakened by quantum fluctuations, enters as a temperature scale the classical-like expressions for the thermal averages, and the quantum spin correlation length is then obtained from its classical counterpart in a simple way. The theory compares very well, for any value of the spin and without need for adjustable parameters, with high temperature expansions, quantum Monte Carlo simulations, and recent neutron and nuclear quadrupole relaxation (NQR) experiments. {copyright} {ital 1997 American Institute of Physics.}

  6. Two Spin Liquid phases in the anisotropic triangular Heisenberg model

    NASA Astrophysics Data System (ADS)

    Sorella, Sandro

    2005-03-01

    Recently there have been rather clean experimental realizations of the quantum spin 1/2 Heisenberg Hamiltonian on a 2D triangular lattice geometry in systems like Cs2Cu Cl4 and organic compounds like k-(ET)2Cu2(CN)3. These materials are nearly two dimensional and are characterized by an anisotropic antiferromagnetic superexchange. The strength of the spatial anisotropy can increase quantum fluctuations and can destabilize the magnetically ordered state leading to non conventional spin liquid phases. In order to understand these interesting phenomena we have studied, by Quantum Monte Carlo methods, the triangular lattice Heisenberg model as a function of the strength of this anisotropy, represented by the ratio r between the intra-chain nearest neighbor coupling J' and the inter-chain one J. We have found evidence of two spin liquid regions, well represented by projected BCS wave functions[1,2] of the type proposed by P. W. Anderson at the early stages of High temperature superconductivity [3]. The first spin liquid phase is stable for small values of the coupling r 0.6 and appears gapless and fractionalized, whereas the second one is a more conventional spin liquid, very similar to the one realized in the quantum dimer model in the triangular lattice[4]. It is characterized by a spin gap and a finite correlation length, and appears energetically favored in the region 0.6 r 0.9. The various phases are in good agreement with the experimental findings and supports the existence of spin liquid phases in 2D quantum spin-half systems. %%%%%%%%%%%%%%%%%% 1cm *[1] L. Capriotti F. Becca A. Parola and S. Sorella , Phys. Rev. Letters 87, 097201 (2001). *[2] S. Yunoki and S. Sorella Phys. Rev. Letters 92, 15003 (2004). *[3] P. W. Anderson, Science 235, 1186 (1987). *[4] P. Fendley, R. Moessner, and S. L. Sondhi Phys. Rev. B 66, 214513 (2002).

  7. Unified molecular field theory for collinear and noncollinear Heisenberg antiferromagnets

    SciTech Connect

    Johnston, David C.

    2015-02-27

    In this study, a unified molecular field theory (MFT) is presented that applies to both collinear and planar noncollinear Heisenberg antiferromagnets (AFs) on the same footing. The spins in the system are assumed to be identical and crystallographically equivalent. This formulation allows calculations of the anisotropic magnetic susceptibility χ versus temperature T below the AF ordering temperature TN to be carried out for arbitrary Heisenberg exchange interactions Jij between arbitrary neighbors j of a given spin i without recourse to magnetic sublattices. The Weiss temperature θp in the Curie-Weiss law is written in terms of the Jij values and TN in terms of the Jij values and an assumed AF structure. Other magnetic and thermal properties are then expressed in terms of quantities easily accessible from experiment as laws of corresponding states for a given spin S. For collinear ordering these properties are the reduced temperature t=T/TN, the ratio f = θp/TN, and S. For planar noncollinear helical or cycloidal ordering, an additional parameter is the wave vector of the helix or cycloid. The MFT is also applicable to AFs with other AF structures. The MFT predicts that χ(T ≤ TN) of noncollinear 120° spin structures on triangular lattices is isotropic and independent of S and T and thus clarifies the origin of this universally observed behavior. The high-field magnetization and heat capacity for fields applied perpendicular to the ordering axis (collinear AFs) and ordering plane (planar noncollinear AFs) are also calculated and expressed for both types of AF structures as laws of corresponding states for a given S, and the reduced perpendicular field versus reduced temperature phase diagram is constructed.

  8. Unified molecular field theory for collinear and noncollinear Heisenberg antiferromagnets

    DOE PAGESBeta

    Johnston, David C.

    2015-02-27

    In this study, a unified molecular field theory (MFT) is presented that applies to both collinear and planar noncollinear Heisenberg antiferromagnets (AFs) on the same footing. The spins in the system are assumed to be identical and crystallographically equivalent. This formulation allows calculations of the anisotropic magnetic susceptibility χ versus temperature T below the AF ordering temperature TN to be carried out for arbitrary Heisenberg exchange interactions Jij between arbitrary neighbors j of a given spin i without recourse to magnetic sublattices. The Weiss temperature θp in the Curie-Weiss law is written in terms of the Jij values and TNmore » in terms of the Jij values and an assumed AF structure. Other magnetic and thermal properties are then expressed in terms of quantities easily accessible from experiment as laws of corresponding states for a given spin S. For collinear ordering these properties are the reduced temperature t=T/TN, the ratio f = θp/TN, and S. For planar noncollinear helical or cycloidal ordering, an additional parameter is the wave vector of the helix or cycloid. The MFT is also applicable to AFs with other AF structures. The MFT predicts that χ(T ≤ TN) of noncollinear 120° spin structures on triangular lattices is isotropic and independent of S and T and thus clarifies the origin of this universally observed behavior. The high-field magnetization and heat capacity for fields applied perpendicular to the ordering axis (collinear AFs) and ordering plane (planar noncollinear AFs) are also calculated and expressed for both types of AF structures as laws of corresponding states for a given S, and the reduced perpendicular field versus reduced temperature phase diagram is constructed.« less

  9. Unified molecular field theory for collinear and noncollinear Heisenberg antiferromagnets

    NASA Astrophysics Data System (ADS)

    Johnston, David C.

    2015-02-01

    A unified molecular field theory (MFT) is presented that applies to both collinear and planar noncollinear Heisenberg antiferromagnets (AFs) on the same footing. The spins in the system are assumed to be identical and crystallographically equivalent. This formulation allows calculations of the anisotropic magnetic susceptibility χ versus temperature T below the AF ordering temperature TN to be carried out for arbitrary Heisenberg exchange interactions Ji j between arbitrary neighbors j of a given spin i without recourse to magnetic sublattices. The Weiss temperature θp in the Curie-Weiss law is written in terms of the Ji j values and TN in terms of the Ji j values and an assumed AF structure. Other magnetic and thermal properties are then expressed in terms of quantities easily accessible from experiment as laws of corresponding states for a given spin S . For collinear ordering these properties are the reduced temperature t =T /TN , the ratio f =θp/TN , and S . For planar noncollinear helical or cycloidal ordering, an additional parameter is the wave vector of the helix or cycloid. The MFT is also applicable to AFs with other AF structures. The MFT predicts that χ (T ≤TN) of noncollinear 120∘ spin structures on triangular lattices is isotropic and independent of S and T and thus clarifies the origin of this universally observed behavior. The high-field magnetization and heat capacity for fields applied perpendicular to the ordering axis (collinear AFs) and ordering plane (planar noncollinear AFs) are also calculated and expressed for both types of AF structures as laws of corresponding states for a given S , and the reduced perpendicular field versus reduced temperature phase diagram is constructed.

  10. Tm-doped TiO2 and Tm2Ti2O7 pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

    PubMed Central

    De los Santos, Desiré M; Aguilar, Teresa; Sánchez-Coronilla, Antonio; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Piñero, Jose Carlos; Blanco, Ginesa; Martín-Calleja, Joaquín

    2015-01-01

    Summary Tm-doped TiO2 nanoparticles were synthesized using a water-controlled hydrolysis reaction. Analysis was performed in order to determine the influence of the dopant concentration and annealing temperature on the phase, crystallinity, and electronic and optical properties of the resulting material. Various characterization techniques were utilized such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm3+. ICP–AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm3+ was confirmed by X-ray photoelectron spectroscopy and UV–vis spectroscopy: the incorporation of Tm3+ was confirmed by the generation of new absorption bands that could be assigned to Tm3+ transitions. Furthermore, when the samples were annealed at 1173 K, a pyrochlore phase (Tm2Ti2O7) mixed with TiO2 was obtained with a predominant rutile phase. The photodegradation of methylene blue showed that this pyrochlore phase enhanced the photocatalytic activity of the rutile phase. PMID:25821701

  11. Fractional magnetization plateaus of the spin-1/2 Heisenberg orthogonal-dimer chain: Strong-coupling approach developed from the exactly solved Ising-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Verkholyak, Taras; Strečka, Jozef

    2016-10-01

    The spin-1/2 Heisenberg orthogonal-dimer chain is considered within the perturbative strong-coupling approach, which is developed from the exactly solved spin-1/2 Ising-Heisenberg orthogonal-dimer chain with the Heisenberg intradimer and the Ising interdimer couplings. Although the spin-1/2 Ising-Heisenberg orthogonal-dimer chain exhibits just intermediate plateaus at zero, one-quarter, and one-half of the saturation magnetization, the perturbative treatment up to second order stemming from this exactly solvable model additionally corroborates the fractional one-third plateau as well as the gapless Luttinger spin-liquid phase. It is evidenced that the approximate results obtained from the strong-coupling approach are in an excellent agreement with the state-of-the-art numerical data obtained for the spin-1/2 Heisenberg orthogonal-dimer chain within the exact diagonalization and density-matrix renormalization group method. The nature of individual quantum ground states is comprehensively studied within the developed perturbation theory.

  12. Role of vein-phases in nanoscale sequestration of U, Nb, Ti, and Pb during the alteration of pyrochlore

    NASA Astrophysics Data System (ADS)

    Deditius, Artur P.; Smith, Frances N. (Skomurski); Utsunomiya, Satoshi; Ewing, Rodney C.

    2015-02-01

    Grains of pyrochlore and secondary phases from tailings of Silver Crater Mine in Bancroft, Ontario (Canada) have been studied to understand the alteration processes, redox conditions, and retention of pyrochlore-derived species (U, Ti, Nb, Pb, Ta, REE) in near-field environments. Alteration processes are documented by the formation of two types of co-existing secondary veins associated with primary apatite and calcite: (i) amorphous Fe-rich veins, 46-75 wt.% of FeO, and ∼500 ppm of UO2, and (ii) crystalline calcite-rich veins, found in fractures and penetrating the pyrochlore. Based on electron microprobe analysis (EMPA), the chemical composition of the pyrochlore is: (Ca0.84U0.35Fe0.20Na0.09Pb0.04Ln0.04Mn0.03Sr0.01Th0.01Mg0.01)1.62 (Nb1.00Ti0.87Ta0.10Si0.02)2.0O6.5F0.14. Elemental mapping revealed that migration of liberated U, Pb, Nb, Ta, Ti, and REE, is confined to the secondary veins of Fe-rich and calcite-rich compositions. Transmission electron microscopy (TEM), high-angle annular dark-field scanning TEM (HAADF-STEM), energy dispersive spectroscopy (EDS), and electron energy loss spectroscopy (EELS) results showed that pyrochlore contains nanoparticulate inclusions of uraninite, galena, and magnetite, while secondary veins host betafite, magnetite, Pb0, cerusite, and 10 Å mica nanoparticles (NPs). Randomly oriented uraninite NPs, 15 nm in size, concentrate around pores, 50-100 nm in size, in the pyrochlore. In the Fe-rich veins, HAADF-STEM images revealed that U, Pb, Nb, and Ti were sequestered in the form of spherical betafite NPs, <800 nm in size, with composition: (Ca1.1Fe0.35Pb0.28U0.09)1.83(Ti1.56Nb0.44)2.0O6.1. The association of betafite NPs, magnetite, and Pb0 NPs in Fe-rich and calcite-rich veins indicates reducing conditions during alteration of pyrochlore and immobilization of pyrochlore derived elements. This observation combined with identification of nanoscale galena and magnetite in pyrochlore, and the association of Pb0 and Fe3O4 in veins

  13. Density matrix renormalization group study of triangular Kitaev-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Sota, Shigetoshi; Sjinjo, Kazuya; Shirakawa, Tomonori; Tohyama, Takami; Yunoki, Seiji

    2015-03-01

    Topological insulator has been one of the most active subjects in the current condensed matter physics. For most of topological insulators electron correlations are considered to be not essential. However, in the case where electron correlations are strong, novel phases such as a spin liquid phase can emerge in competition with a spin-orbit coupling. Here, using the density matrix renormalization group method, we investigate magnetic phase of a triangular Kitaev-Heisenberg (quantum compass) model that contains a spin-orbital interaction and spin frustration in the antiferromagnetic region. The triangular Kitaev-Heisenberg model is regarded as a dual model of the honeycomb Kitaev-Heisenberg model that is usually employed to discuss A2CuO3 (A=Na, K). Systematically calculating ground state energy, entanglement entropy, entanglement spectrum, and spin-spin correlation functions, we discuss the duality between the triangular and the honeycomb Kitaev-Heisenberg model as well as the ground state magnetic phases.

  14. Employing Taylor and Heisenberg subfilter viscosities to simulate turbulent statistics in LES models

    NASA Astrophysics Data System (ADS)

    Degrazia, G. A.; Rizza, U.; Puhales, F. S.; Welter, G. S.; Acevedo, O. C.; Maldaner, S.

    2012-02-01

    A turbulent subfilter viscosity for Large Eddy Simulation (LES) based on the Taylor statistical diffusion theory is proposed. This viscosity is described in terms of a velocity variance and a time scale, both associated to the inertial subrange. This new subfilter viscosity contains a cutoff wavenumber kc, presenting an identical form (differing by a constant) to the Heisenberg subfilter viscosity. Therefore, both subfilter viscosities are described in terms of a sharp division between large and small wavenumbers of a turbulent flow and, henceforth, Taylor and Heisenberg subfilter viscosities are in agreement with the sharp Fourier filtering operation, frequently employed in LES models. Turbulent statistics of different orders, generated from atmospheric boundary layer simulations employing both Taylor and Heisenberg subfilter viscosities have been compared with observations and results provided by other simulations. The comparison shows that the LES model utilizing the approaches of Taylor and Heisenberg reproduces these turbulent statistics correctly in different vertical regions of a planetary convective boundary layer (CBL).

  15. Bernhard Riemann, a(rche)typical mathematical-physicist?

    NASA Astrophysics Data System (ADS)

    Elizalde, Emilio

    2013-09-01

    The work of Bernhard Riemann is discussed under the perspective of present day mathematics and physics, and with a prospective view towards the future, too. Against the (unfortunately rather widespread) trend---which predominantly dominated national scientific societies in Europe during the last Century---of strictly classifying the work of scientists with the aim to constrain them to separated domains of knowledge, without any possible interaction among those and often even fighting against each other (and which, no doubt, was in part responsible for the decline of European in favor of American science), it will be here argued, using Riemann as a model, archetypical example, that good research transcends any classification. Its uses and applications arguably permeate all domains, subjects and disciplines one can possibly define, to the point that it can be considered to be universally useful. After providing a very concise review of the main publications of Bernhard Riemann on physical problems, some connections between Riemann's papers and contemporary physics will be considered: (i) the uses of Riemann's work on the zeta function for devising applications to the regularization of quantum field theories in curved space-time, in particular, of quantum vacuum fluctuations; (ii) the uses of the Riemann tensor in general relativity and in recent generalizations of this theory, which aim at understanding the presently observed acceleration of the universe expansion (the dark energy issue). Finally, it will be argued that mathematical physics, which was yet not long ago a model paradigm for interdisciplinary activity---and had a very important pioneering role in this sense---is now quickly being surpassed by the extraordinarily fruitful interconnections which seem to pop up from nothing every day and simultaneously involve several disciplines, in the classical sense, including genetics, combinatorics, nanoelectronics, biochemistry, medicine, and even ps

  16. The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

    2005-01-01

    A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

  17. Adiabatic demagnetization of the antiferromagnetic spin-1/2 Heisenberg hexagonal cluster

    NASA Astrophysics Data System (ADS)

    Deb, Moumita; Ghosh, Asim Kumar

    2016-05-01

    Exact analytic expressions of eigenvalues of the antiferromagnetic spin-1/2 Heisenberg hexagon in the presence of uniform magnetic field have been obtained. Magnetization process, nature of isentrops and properties of magneto caloric effect in terms of adiabatic demagnetization have been investigated. Theoretical results have been used to study the magneto caloric effect of the spin-1/2 Heisenberg hexagonal compound Cu3WO6.

  18. Werner Heisenberg and Carl Friedrich Freiherr von Weizsäcker: A Fifty-Year Friendship*

    NASA Astrophysics Data System (ADS)

    Cassidy, David C.

    2015-03-01

    This paper follows Werner Heisenberg and Carl Friedrich von Weizsäcker during their fifty-year friendship from 1926, when they first met in Copenhagen, to Heisenberg's death in Munich in 1976. The relationship underwent profound changes during that period, as did physics, philosophy, and German society and politics, all of which exerted important influences on their lives, work, and interactions with each other. The nature of these developments and their impact are explored in this paper.

  19. The Heisenberg-Euler Lagrangian as an example of an effective field theory

    NASA Astrophysics Data System (ADS)

    Dittrich, Walter

    2014-10-01

    We review the beginning of the effective Lagrangian in QED that was first introduced in the literature by W. Heisenberg and H. Euler in 1936. Deviating from their way of calculating the one-loop effective correction to the classical Maxwell Lagrangian, we use Green's functions and adopt the Fock-Schwinger proper-time method. The important role of the Heisenberg-Euler effective Lagrangian is explicitly demonstrated for low-energy photon-photon processes.

  20. Nuclear waste disposal—pyrochlore (A2B2O7): Nuclear waste form for the immobilization of plutonium and "minor" actinides

    NASA Astrophysics Data System (ADS)

    Ewing, Rodney C.; Weber, William J.; Lian, Jie

    2004-06-01

    During the past half-century, the nuclear fuel cycle has generated approximately 1400 metric tons of plutonium and substantial quantities of the "minor" actinides, such as Np, Am, and Cm. The successful disposition of these actinides has an important impact on the strategy for developing advanced nuclear fuel cycles, weapons proliferation, and the geologic disposal of high-level radioactive waste. During the last decade, there has been substantial interest in the use of the isometric pyrochlore structure-type, A2B2O7, for the immobilization of actinides. Most of the interest has focused on titanate-pyrochlore because of its chemical durability; however, these compositions experience a radiation-induced transition from the crystalline-to-aperiodic state due to radiation damage from the alpha-decay of actinides. Depending on the actinide concentration, the titanate pyrochlore will become amorphous in less than 1000 years of storage. Recently, systematic ion beam irradiations of a variety of pyrochlore compositions has revealed that many zirconate pyrochlores do not become amorphous, but remain crystalline as a defect fluorite structure-type due to disordering of the A- and B-site cations. The zirconate pyrochlores will remain crystalline even to very high doses, greater than 100 displacements per atom. Systematic experimental studies of actinide-doped and ion beam-irradiated pyrochlore, analyses of natural U- and Th-bearing pyrochlore, and simulations of the energetics of the disordering process now provide a rather detailed understanding of the structural and chemical controls on the response of pyrochlore to radiation. These results provide a solid basis for predicting the behavior and durability of pyrochlore used to immobilize plutonium.

  1. Activity of JC virus archetype and PML-type regulatory regions in glial cells.

    PubMed

    Ault, G S

    1997-01-01

    Sequence variations are seen in the JC virus promoter/enhancer in virus taken from progressive multifocal leukoencephalopathy (PML) brains and it has been hypothesized that the variations arise in the host at some point in the development of PML. These rearrangements may be adaptations for enhanced growth in glial cells; if so, transcription or replication levels should differ between archetypal and rearranged PML-type promoters. The archetype and four PML-type promoters were analysed in human glial cells for early and late transcriptional activity in the absence or presence of virus T antigen, and for DNA replication. CAT reporter expression differed within a fivefold range and the archetype was intermediate in strength to the PML-type regulatory regions. The archetype differed from rearranged promoters in that the late promoter was less responsive to T antigen and the shift from early to late activity with T antigen was less pronounced. All five regulatory regions demonstrated similar levels of DNA replicating activity. Rearrangement of the archetype was not required for activity in glial cells, but the potential for differences in the regulation of the late capsid genes was found.

  2. Integrating reasoning and clinical archetypes using OWL ontologies and SWRL rules.

    PubMed

    Lezcano, Leonardo; Sicilia, Miguel-Angel; Rodríguez-Solano, Carlos

    2011-04-01

    Semantic interoperability is essential to facilitate the computerized support for alerts, workflow management and evidence-based healthcare across heterogeneous electronic health record (EHR) systems. Clinical archetypes, which are formal definitions of specific clinical concepts defined as specializations of a generic reference (information) model, provide a mechanism to express data structures in a shared and interoperable way. However, currently available archetype languages do not provide direct support for mapping to formal ontologies and then exploiting reasoning on clinical knowledge, which are key ingredients of full semantic interoperability, as stated in the SemanticHEALTH report [1]. This paper reports on an approach to translate definitions expressed in the openEHR Archetype Definition Language (ADL) to a formal representation expressed using the Ontology Web Language (OWL). The formal representations are then integrated with rules expressed with Semantic Web Rule Language (SWRL) expressions, providing an approach to apply the SWRL rules to concrete instances of clinical data. Sharing the knowledge expressed in the form of rules is consistent with the philosophy of open sharing, encouraged by archetypes. Our approach also allows the reuse of formal knowledge, expressed through ontologies, and extends reuse to propositions of declarative knowledge, such as those encoded in clinical guidelines. This paper describes the ADL-to-OWL translation approach, describes the techniques to map archetypes to formal ontologies, and demonstrates how rules can be applied to the resulting representation. We provide examples taken from a patient safety alerting system to illustrate our approach.

  3. X-ray diffraction study of the Y2Ti2O7 pyrochlore disordering sequence under irradiation

    NASA Astrophysics Data System (ADS)

    Soulié, Aurélien; Menut, Denis; Crocombette, Jean-Paul; Chartier, Alain; Sellami, Neila; Sattonnay, Gaël; Monnet, Isabelle; Béchade, Jean-Luc

    2016-11-01

    The disordering sequence of Y2Ti2O7 pyrochlore, a nano-oxide phase that strengthens ODS steels under irradiation is studied in the experimental and modeling framework. XRD analysis has been performed considering both swift heavy ion and low energy/low mass ion irradiations. The simulation within molecular dynamics of Frenkel pair accumulation proves able to reproduce the variation of the amorphization fluence with temperature. XRD patterns calculated from the simulations reproduce well the patterns observed experimentally in the literature. Both experiments and calculations point to a first transition from pyrochlore to fluorite before an eventual amorphization. For swift heavy ion irradiations with 93 MeV Xe ions, tracks of direct impact amorphization are visible by HRTEM. Advanced refinement shows that one third of the pyrochlore impacted by an ion transforms into fluorite, while two third are directly amorphized.

  4. Electronic excitation induced amorphization in titanate pyrochlores: an ab initio molecular dynamics study

    SciTech Connect

    Xiao, Haiyan Y.; Weber, William J.; Zhang, Yanwen; Zu, X. T.; Li, Sean

    2015-02-09

    In this study, the response of titanate pyrochlores (A2Ti2O7, A = Y, Gd and Sm) to electronic excitation is investigated utilizing an ab initio molecular dynamics method. All the titanate pyrochlores are found to undergo a crystalline-to-amorphous structural transition under a low concentration of electronic excitations. The transition temperature at which structural amorphization starts to occur depends on the concentration of electronic excitations. During the structural transition, O2-like molecules are formed, and this anion disorder further drives cation disorder that leads to an amorphous state. This study provides new insights into the mechanisms of amorphization in titanate pyrochlores under laser, electron and ion irradiations.

  5. Speciation of uranium in La{sub 2}Zr{sub 2}O{sub 7} pyrochlore by TRPLS

    SciTech Connect

    Mohapatra, M.; Rajeswari, B.; Hon, N. S.; Kadam, R. M. Natarajan, V.

    2015-06-24

    We discuss the speciation of uranium in lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7} =LZO) pyrochlore ceramic prepared via a gel-combustion route. Uranium concentration in the pyrochlore was optimized to 2 mol%. XRD and SEM experiments were carried out to assess the phase and homogeneity of the prepared samples. Time resolved photoluminescence (TRPLS) investigations were carried out for understanding the species stabilized in the pyrochlore host. It was observed that, uranium exists as uranate ion (UO{sub 6}{sup 6−}) in the zirconate host where it replaces the ‘Zr’ ions at its regular site with surrounding defect centers created for charge compensation.

  6. Pyrochlore-structured titanate ceramics for immobilisation of actinides: Hot isostatic pressing (HIPing) and stainless steel/waste form interactions

    NASA Astrophysics Data System (ADS)

    Zhang, Yingjie; Li, Huijun; Moricca, Sam

    2008-07-01

    A pyrochlore-structured titanate ceramic has been studied in respect of its overall feasibility for immobilisation of impure actinide-rich radioactive wastes through the hot isostatic pressing (HIPing) technique. The resultant waste form contains mainly pyrochlore (˜70%), rutile (˜14%) as well as perovskite (˜12%), hollandite (˜2%) and brannerite (˜1%). Optical spectroscopy confirms that uranium (used to simulate Pu) exists mainly in the stable pyrochlore-structured phase as tetravalent ions as designed. The stainless steel/waste form interactions under HIPing conditions (1280 °C/100 MPa/3 h) do not seem to change the actinide-bearing phases and therefore should have no detrimental effect on the waste form.

  7. Standardized and flexible health data management with an archetype driven EHR system (EHRflex).

    PubMed

    Brass, Anton; Moner, David; Hildebrand, Claudia; Robles, Montserrat

    2010-01-01

    To build a semantically interoperable Electronic Health Record is one of the most challenging research fields in health informatics. In order to reach this objective, EHR standards that formally describe health data structures have to be used. CEN EN13606 is one of the most promising approaches. It covers the technical needs for semantic interoperability and, at the same time, it incorporates a mechanism (archetype model) that enables clinical domain experts to participate in building an EHR system. In this paper we present EHRflex, a generic system based on archetypes. It empowers the clinician and allows him to manage his own EHR system in a simple and generic way, assuring that the user works with underlying standardized data structures. These can be exchanged with other people and systems when needed. EHRflex introduces EHR standards into the clinical routine delivering a technical platform which works directly on archetype based data.

  8. Using archetypes to create user panels for usability studies: Streamlining focus groups and user studies.

    PubMed

    Stavrakos, S-K; Ahmed-Kristensen, S; Goldman, T

    2016-09-01

    Designers at the conceptual phase of products such as headphones, stress the importance of comfort, e.g. executing comfort studies and the need for a reliable user panel. This paper proposes a methodology to issue a reliable user panel to represent large populations and validates the proposed framework to predict comfort factors, such as physical fit. Data of 200 heads was analyzed by forming clusters, 9 archetypal people were identified out of a 200 people's ear database. The archetypes were validated by comparing the archetypes' responses on physical fit against those of 20 participants interacting with 6 headsets. This paper suggests a new method of selecting representative user samples for prototype testing compared to costly and time consuming methods which relied on the analysis of human geometry of large populations. PMID:27184318

  9. Using archetypes to create user panels for usability studies: Streamlining focus groups and user studies.

    PubMed

    Stavrakos, S-K; Ahmed-Kristensen, S; Goldman, T

    2016-09-01

    Designers at the conceptual phase of products such as headphones, stress the importance of comfort, e.g. executing comfort studies and the need for a reliable user panel. This paper proposes a methodology to issue a reliable user panel to represent large populations and validates the proposed framework to predict comfort factors, such as physical fit. Data of 200 heads was analyzed by forming clusters, 9 archetypal people were identified out of a 200 people's ear database. The archetypes were validated by comparing the archetypes' responses on physical fit against those of 20 participants interacting with 6 headsets. This paper suggests a new method of selecting representative user samples for prototype testing compared to costly and time consuming methods which relied on the analysis of human geometry of large populations.

  10. Archetypal Dreams: the Quantum Theater of Robert Wilson

    NASA Astrophysics Data System (ADS)

    Dietrich, Dawn Yvette

    1992-01-01

    My topic is situated within the larger framework of interdisciplinary study currently exploring the impact of new physics on various "soft" disciplines and sciences. Aligning myself with thinkers like Fritjof Capra and N. Katherine Hayles, who argue that quantum mechanics has brought about a new paradigm for the conceptualization of the physical world and our relation to it, I demonstrate that there is a connection, a kind of cultural translation, which relates contemporary physics to some avant-garde theater. Specifically, I center my research on American theater designer, Robert Wilson, who, recognized for his manipulation of the formal elements of stagecraft, owes much to the reconstruction of principles governing space and time. Taken further, I maintain that it is through the paradigm established from relativity theory and quantum mechanics that Wilson experiments with the elementary "forces" of the theater itself. This "restructuring" occurs through the dramatist's conceptions of space and time and the relation of those properties to both performers and spectators. Unlike most conventional theater, but as in many contemporary visual arts, time is manipulated through spatial metaphors and events take place in an amplified space--effecting a kind of dramatic space/time. Through manipulation of scale, the exploration of discontinuous time, and segregated stage zones, Wilson demonstrates that theater time is fluid and that it is not necessary for dramatic action to take place within the unified stage space delineated by the proscenium itself. Unlike conventional theater, where the stage is constructed with one perspective in mind, Wilson's theatrical mise-en-scene--a kind of new "perceptual field"--requires "imaginative watching"; that is, more perceptual discrimination from the audience who must sort and organize the visual material, highlighting the essential while reconfiguring the incidental. And this is where the myth is born, where archetypal dreams stir

  11. Nonreciprocal spin wave elementary excitation in dislocated dimerized Heisenberg chains.

    PubMed

    Liu, Wanguo; Shen, Yang; Fang, Guisheng; Jin, Chongjun

    2016-05-18

    A mechanism for realizing nonreciprocal elementary excitation of spin wave (SW) is proposed. We study a reference model which describes a magnonic crystal (MC) formed by two Heisenberg chains with a lateral displacement (dislocation) and a longitudinal spacer, and derive a criterion to judge whether the elementary excitation spectra are reciprocal in this ferromagnetic lattice. An analytical method based on the spin precession equation is used to solve the elementary excitation spectra. The solution is related to a key factor, the spatio-temporal structure factor [Formula: see text], which can be directly calculated through the structural parameters. When it keeps invariant under the reversions of the external magnetic field [Formula: see text] and the dislocation [Formula: see text], or one of them, the spectra are reciprocal. Otherwise, the SW possesses nonreciprocal spectra with direction-dependent band edges and exhibits a directional magnetoresistance effect. This criterion can be regarded as a necessary and sufficient condition for the (non)reciprocity in the spin lattice. Besides, this novel lattice provides a prototype for spin diodes and spin logic gates. PMID:27092428

  12. Soft Heisenberg hair on black holes in three dimensions

    NASA Astrophysics Data System (ADS)

    Afshar, Hamid; Detournay, Stephane; Grumiller, Daniel; Merbis, Wout; Perez, Alfredo; Tempo, David; Troncoso, Ricardo

    2016-05-01

    Three-dimensional Einstein gravity with a negative cosmological constant admits stationary black holes that are not necessarily spherically symmetric. We propose boundary conditions for the near-horizon region of these black holes that lead to a surprisingly simple near-horizon symmetry algebra consisting of two affine u ^(1 ) current algebras. The symmetry algebra is essentially equivalent to the Heisenberg algebra. The associated charges give a specific example of "soft hair" on the horizon, as defined by Hawking, Perry and Strominger. We show that soft hair does not contribute to the Bekenstein-Hawking entropy of Bañados-Teitelboim-Zanelli black holes and "black flower" generalizations. From the near-horizon perspective the conformal generators at asymptotic infinity appear as composite operators, which we interpret in the spirit of black hole complementarity. Another remarkable feature of our boundary conditions is that they are singled out by requiring that the whole spectrum is compatible with regularity at the horizon, regardless of the value of the global charges like mass or angular momentum. Finally, we address black hole microstates and generalizations to cosmological horizons.

  13. Valence bond distribution and correlation in bipartite Heisenberg antiferromagnets

    NASA Astrophysics Data System (ADS)

    Schwandt, David; Alet, Fabien; Oshikawa, Masaki

    2014-03-01

    Every singlet state of a quantum spin-1/2 system can be decomposed into a linear combination of valence bond basis states. The range of valence bonds within this linear combination as well as the correlations between them can reveal the nature of the singlet state and are key ingredients in variational calculations. In this work, we study the bipartite valence bond distributions and their correlations within the ground state of the Heisenberg antiferromagnet on bipartite lattices. In terms of field theory, this problem can be mapped to correlation functions near a boundary. In dimension d ≥2, a nonlinear σ model analysis reveals that at long distances the probability distribution P (r) of valence bond lengths decays as |r|-d-1 and that valence bonds are uncorrelated. By a bosonization analysis, we also obtain P(r )∝|r|-d-1 in d =1 despite the different mechanism. On the other hand, we find that correlations between valence bonds are important even at large distances in d =1, in stark contrast to d ≥2. The analytical results are confirmed by high-precision quantum Monte Carlo simulations in d =1, 2, and 3. We develop a single-projection loop variant of the valence bond projection algorithm, which is well designed to compute valence bond probabilities and for which we provide algorithmic details.

  14. Variational Monte Carlo investigation of SU (N ) Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Dufour, Jérôme; Nataf, Pierre; Mila, Frédéric

    2015-05-01

    Motivated by recent experimental progress in the context of ultracold multicolor fermionic atoms in optical lattices, we have investigated the properties of the SU (N) Heisenberg chain with totally antisymmetric irreducible representations, the effective model of Mott phases with m

  15. Field dependent spin transport of anisotropic Heisenberg chain

    NASA Astrophysics Data System (ADS)

    Rezania, H.

    2016-04-01

    We have addressed the static spin conductivity and spin Drude weight of one-dimensional spin-1/2 anisotropic antiferromagnetic Heisenberg chain in the finite magnetic field. We have investigated the behavior of transport properties by means of excitation spectrum in terms of a hard core bosonic representation. The effect of in-plane anisotropy on the spin transport properties has also been studied via the bosonic model by Green's function approach. This anisotropy is considered for exchange constants that couple spin components perpendicular to magnetic field direction. We have found the temperature dependence of the spin conductivity and spin Drude weight in the gapped field induced spin-polarized phase for various magnetic field and anisotropy parameters. Furthermore we have studied the magnetic field dependence of static spin conductivity and Drude weight for various anisotropy parameters. Our results show the regular part of spin conductivity vanishes in isotropic case however Drude weight has a finite non-zero value and the system exhibits ballistic transport properties. We also find the peak in the static spin conductivity factor moves to higher temperature upon increasing the magnetic field at fixed anisotropy. The static spin conductivity is found to be monotonically decreasing with magnetic field due to increase of energy gap in the excitation spectrum. Furthermore we have studied the temperature dependence of spin Drude weight for different magnetic field and various anisotropy parameters.

  16. Stapp's quantum dualism: The James and Heisenberg model of consciousness

    NASA Astrophysics Data System (ADS)

    Noyes, H. P.

    1994-02-01

    Henry Stapp attempts to resolve the Cartesian dilemma by introducing what the author would characterize as an ontological dualism between mind and matter. His model for mind comes from William James' description of conscious events and for matter from Werner Heisenberg's ontological model for quantum events (wave function collapse). His demonstration of the isomorphism between the two types of events is successful, but in the author's opinion fails to establish a monistic, scientific theory. The author traces Stapp's failure to his adamant rejection of arbitrariness, or 'randomness.' This makes it impossible for him (or for Bohr and Pauli before him) to understand the power of Darwin's explanation of biology, let alone the triumphs of modern 'neo-Darwinism.' The author notes that the point at issue is a modern version of the unresolved opposition between Leucippus and Democritus on one side and Epicurus on the other. Stapp's views are contrasted with recent discussions of consciousness by two eminent biologists: Crick and Edelman. They locate the problem firmly in the context of natural selection on the surface of the earth. Their approaches provide a sound basis for further scientific work. The author briefly examines the connection between this scientific (rather than ontological) framework and the new fundamental theory based on bit-strings and the combinatorial hierarchy.

  17. Ordering of the Heisenberg spin glass in two dimensions

    NASA Astrophysics Data System (ADS)

    Kawamura, Hikaru; Yonehara, Hitoshi

    2003-10-01

    The spin and the chirality orderings of the Heisenberg spin glass in two dimensions with the nearest-neighbour Gaussian coupling are investigated by equilibrium Monte Carlo simulations. Particular attention is paid to the behaviour of the spin and the chirality correlation lengths. In order to observe the true asymptotic behaviour, a fairly large system size L gap 20 (L the linear dimension of the system) appears to be necessary. It is found that both the spin and the chirality order only at zero temperature. At high temperatures, the chiral correlation length stays shorter than the spin correlation length, whereas at lower temperatures below the crossover temperature T×, the chiral correlation length exceeds the spin correlation length. The spin and the chirality correlation-length exponents are estimated above T× to be ngrSG = 0.9 ± 0.2 and ngrCG = 2.1 ± 0.3, respectively. These values are close to the previous estimates on the basis of the domain-wall-energy calculation. Discussion is given about the asymptotic critical behaviour realized below T×.

  18. NMR spin relaxation rates in the Heisenberg bilayer

    NASA Astrophysics Data System (ADS)

    Mendes, Tiago; Curro, Nicholas; Scalettar, Richard; Paiva, Thereza; Dos Santos, Raimundo R.

    One of the striking features of heavy fermions is the fact that in the vicinity of a quantum phase transition these systems exhibit the breakdown of Fermi-liquid behavior and superconductivity. Nuclear magnetic resonance (NMR) expirements play an important role in the study of these phenomena. Measurements of NMR spin relaxation rates and Knight shift, for instance, can be used to probe the electronic spin susceptibility of these systems. Here we studied the NMR response of the Heisenberg bilayer model. In this model, it is well known that the increase of the interplane coupling between the planes, Jperp, supresses the antiferromagnetic order at a quantum critical point (QCP). We use stochastic series expansion (SSE) and the maximum-entropy analytic continuation method to calculate the NMR spin lattice relaxation rate 1 /T1 and the spin echo decay 1 /T2 G as function of Jperp. The spin echo decay, T2 G increases for small Jperp, due to the increase of the order parameter, and then vanishes abruptly in the QCP. The effects of Jperp dilution disorder in the QCP and the relaxation rates are also discussed. This research was supported by the NNSA Grant Number DE-NA 0002908, and Ciência sem fronteiras program/CNPQ.

  19. Nonreciprocal spin wave elementary excitation in dislocated dimerized Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Liu, Wanguo; Shen, Yang; Fang, Guisheng; Jin, Chongjun

    2016-05-01

    A mechanism for realizing nonreciprocal elementary excitation of spin wave (SW) is proposed. We study a reference model which describes a magnonic crystal (MC) formed by two Heisenberg chains with a lateral displacement (dislocation) and a longitudinal spacer, and derive a criterion to judge whether the elementary excitation spectra are reciprocal in this ferromagnetic lattice. An analytical method based on the spin precession equation is used to solve the elementary excitation spectra. The solution is related to a key factor, the spatio-temporal structure factor {θk}≤ft(Δ x,B\\right) , which can be directly calculated through the structural parameters. When it keeps invariant under the reversions of the external magnetic field B and the dislocation Δ x , or one of them, the spectra are reciprocal. Otherwise, the SW possesses nonreciprocal spectra with direction-dependent band edges and exhibits a directional magnetoresistance effect. This criterion can be regarded as a necessary and sufficient condition for the (non)reciprocity in the spin lattice. Besides, this novel lattice provides a prototype for spin diodes and spin logic gates.

  20. From Spin Glass to Spin Liquid Ground States in Pyrochlore Molybdates

    NASA Astrophysics Data System (ADS)

    Clark, Lucy

    Magnetic pyrochlores continue to generate intense interest due to the wealth of interesting behaviours that they can display as a result of their highly frustrated nature. Here we will present our study of the molybdate pyrochlore Lu2Mo2O7, which contains non-magnetic Lu3+ and an antiferromagnetic network of corner-sharing tetrahedra of Mo4+ 4d2 S = 1 ions. Magnetic susceptibility data show that Lu2Mo2O7 enters an unconventional spin glass state at Tf ~ 16 K that displays a quadratic dependence of the low temperature magnetic heat capacity, akin to that observed for its well-studied sister compound Y2Mo2O7. This spin glass transition is also clearly marked in our inelastic (CNCS, SNS) and diffuse elastic magnetic (D7, ILL) neutron scattering data. Furthermore, we will show that it is possible to topochemically substitute the oxide, O2-, ions within Lu2Mo2O7 for nitride, N3-, to produce an oxynitride molybdate pyrochlore of composition Lu2Mo2O5N2. Magnetic susceptibility measurements confirm that strong antiferromagnetic correlations persist within the oxynitride, which contains Mo5+ 4d1 S =1/2 ions and is thus a prime candidate to host exotic quantum spin liquid behavior. We will discuss how the enhanced quantum spin fluctuations in Lu2Mo2O5N2 appear to suppress the spin freezing transition observed in its parent oxide and instead support the formation of a gapless spin liquid phase that displays a linear dependence of the low temperature magnetic heat capacity.

  1. Reconceptualizing the Archetypal Trickster in Audre Lorde's Zami: A New Spelling of My Name.

    PubMed

    Saber, Yomna

    2015-01-01

    Carl Jung categorizes the trickster as a psychological archetype and sets certain parameters for it. This article examines Audre Lorde's trickster Afrekete in Zami: A New Spelling of My Name (1982) and poses the question of how typically archetypal a Black, female, lesbian trickster can be. Lorde occupies an idiosyncratic position in the canon in terms of race, gender, and sexual orientation. She bestows new qualities on her trickster coming from the peripheries she dwells in and challenges the Jungian model. Through Afrekete's linguistic dexterity and sexual identity, Lorde transforms the trickster from being seemingly innocuous into a figure of resistance grounded in lesbian erotica. PMID:26264993

  2. Reconceptualizing the Archetypal Trickster in Audre Lorde's Zami: A New Spelling of My Name.

    PubMed

    Saber, Yomna

    2015-01-01

    Carl Jung categorizes the trickster as a psychological archetype and sets certain parameters for it. This article examines Audre Lorde's trickster Afrekete in Zami: A New Spelling of My Name (1982) and poses the question of how typically archetypal a Black, female, lesbian trickster can be. Lorde occupies an idiosyncratic position in the canon in terms of race, gender, and sexual orientation. She bestows new qualities on her trickster coming from the peripheries she dwells in and challenges the Jungian model. Through Afrekete's linguistic dexterity and sexual identity, Lorde transforms the trickster from being seemingly innocuous into a figure of resistance grounded in lesbian erotica.

  3. ResearchEHR: use of semantic web technologies and archetypes for the description of EHRs.

    PubMed

    Robles, Montserrat; Fernández-Breis, Jesualdo Tomás; Maldonado, Jose A; Moner, David; Martínez-Costa, Catalina; Bosca, Diego; Menárguez-Tortosa, Marcos

    2010-01-01

    In this paper, we present the ResearchEHR project. It focuses on the usability of Electronic Health Record (EHR) sources and EHR standards for building advanced clinical systems. The aim is to support healthcare professional, institutions and authorities by providing a set of generic methods and tools for the capture, standardization, integration, description and dissemination of health related information. ResearchEHR combines several tools to manage EHR at two different levels. The internal level that deals with the normalization and semantic upgrading of exiting EHR by using archetypes and the external level that uses Semantic Web technologies to specify clinical archetypes for advanced EHR architectures and systems.

  4. Continuous Synthesis of Doped Pyrochlore Materials by Spray Pyrolysis for Auto-thermal Reforming Applications

    NASA Astrophysics Data System (ADS)

    Yancey, Jonathan

    The use of a spray-pyrolysis method is studied for the continuous synthesis of refractory oxide reforming catalyst for the conversion of hydrocarbon fuels to H2 and CO at 900°C. Nickel- and rhodium-doped zirconate pyrochlore materials with the formulas La1.89Ni2.81Y 0.25Ca0.11Zr1.47 and La1.89Rh 1.09Y0.25Ca0.11Zr1.641 were synthesized using the spray pyrolysis method. Both Pechini and glycine-nitrate precursor solutions were used in order to control the particle morphology, crystallinity, and surface area of the catalyst powder. Samples synthesized by the Pechini solution required post-synthesis heat treatment to 1000 °C for 2 hours to form the fully-crystalline pyrochlore phase. Both the Ni- and Rh-doped compositions formed by the spray-pyrolysis method performed as reported elsewhere for powder produced by solid-state and Pechini bulk methods. The use of the glycine-nitrate precursor solution in the spray-pyrolysis resulted in the formation of fully crystalline pyrochlore catalyst for the Ni-doped composition without any additional high temperature treatment. The Rh-doped catalysts synthesized from the glycine-nitrate precursor did not form a fully crystalline material directly from the spray-pyrolysis process, but required a further thermal treatment to 800 °C for 8 hours to transform the powder and burn-off excess carbon remaining from the synthesis process. Rapid catalyst aging tests for the Rh-doped catalysts synthesized by spray-pyrolysis (using either the Pechini and glycine-nitrate precursor solutions) produced stable and active catalysts achieving equilibrium hydrogen yield of 90% for 15 hours. To conclude, the work showed that through proper chemical design of the precursor system, a high surface area, chemically active, and stable zirconate pyrochlore catalyst could be synthesized efficiently by the spray-pyrolysis method developed.

  5. Key Role of the Cation Interstitial Structure in the Radiation Resistance of Pyrochlores

    SciTech Connect

    Chartier, Alain; Catillon, Gilles; Crocombette, Jean-Paul

    2009-04-17

    The annealing of the B cation interstitial is shown to drive the thermokinetic of the response to irradiations of A{sub 2}B{sub 2}O{sub 7} pyrochlores. Molecular dynamics simulations evidenced that the annealing of interstitials created by irradiations depends upon the nature of B. As the coordination number of B decreases, the dumbbell interstitial is stabilized at the expense of the isolated interstitial. Unlike the isolated interstitials, the recombination of the dumbbells is thermally activated and hindered at low temperatures. The occurrence of dumbbells drives the structure towards the amorphous state.

  6. High local disorder in Tb2Hf2O7 pyrochlore oxide nanocrystals

    NASA Astrophysics Data System (ADS)

    Kabanova, V. A.; Popov, V. V.; Zubavichus, Ya V.; Kulik, E. S.; Yaroslavtsev, A. A.; Chernikov, R. V.; Menushenkov, A. P.

    2016-05-01

    The process of Tb2Hf2O7 nanocrystals formation upon annealing to 1600°C was investigated by means of X-ray absorption fine structure (XAFS) spectroscopy combined with X-ray diffraction (XRD) and pair distribution function (PDF) analysis. The structure ordering and the growth of nanocrystals upon annealing were estimated independently from XRD patterns and PDF. The probable content of Tb4+ ions in Tb2Hf2O7 was estimated from XANES. All studies indicate a high disorder and a large number of local structure defects in Tb2Hf2O7 pyrochlore oxide.

  7. Catalytic partial oxidation of n-tetradecane using pyrochlores: Effect of Rh and Sr substitution

    SciTech Connect

    Haynes, D.; Berry, D.; Shekhawat, D.; Spivey, J.

    2008-01-01

    The catalytic partial oxidation (CPOX) of transportation fuels into synthesis gas (H2 + CO) for fuel cells is complicated by the large quantities of aromatics and sulfur-containing compounds commonly found in these fuels. Traditional supported metal catalysts are easily poisoned by these species which adsorb strongly onto the electron-rich metal clusters. The use of noble metal and/or oxide based catalyst systems may offer higher activity and stability, but only if the metal can be bound into a thermally stable structure. To that end, Rh metal was substituted into the structure of a lanthanum zirconate (LZ) pyrochlore to give La2RhyZr(2 y)O(7-j,) (LRZ) to produce a strongly bound, well-dispersed metal which is active for CPOX. A second catalyst was prepared in which Sr was substituted for a portion of La in the LRZ structure, producing La(2 x)SrxRhyZr(2 y)O(7-j) (LSRZ). Each of these pyrochlore catalysts, including the unsubstituted LZ, were characterized and screened for activity in the CPOX of ntetradecane (TD), which is a surrogate for linear paraffins typical of diesel fuel. Results were compared to a commercial Rh/g-Al2O3 catalyst. X-ray diffraction patterns of both the LZ and LRZ showed that each had the cubic unit-cell pyrochlore structure. However, substitution of Sr resulted in a binary perovskite-pyrochlore phase with a defect SrZrO3 phase. Hydrogen pulse chemisorption and temperature programmed reduction studies confirmed that Rh metal was substituted into the structure of the LRZ and LSRZ, and was reducible. Activity screening with the CPOX of TD showed that the Rh substituted in both LRZ and LSRZ is able to retain activity-producing essentially equilibrium synthesis gas yields, as was the Rh/g-Al2O3. Temperature programmed oxidation experiments performed after the CPOX of TD demonstrated that the amount of carbon was quantitatively similar for each catalyst (roughly 0.3 gcarbon/gcatalyst after each run), with the exception of LSRZ, which had

  8. Catalytic Partial oxidation of n-Tetradecane Using Pyrochlores: Effect of Rh and Sr Substitution

    SciTech Connect

    Haynes, D.J.; Berry, D.A.; Shekhawat, Dushyant; Spivey, J.J.

    2008-07-31

    The catalytic partial oxidation (CPOX) of transportation fuels into synthesis gas (H2 + CO) for fuel cells is complicated by the large quantities of aromatics and sulfur-containing compounds commonly found in these fuels. Traditional supported metal catalysts are easily poisoned by these species which adsorb strongly onto the electron-rich metal clusters. The use of noble metal and/or oxide based catalyst systems may offer higher activity and stability, but only if the metal can be bound into a thermally stable structure. To that end, Rh metal was substituted into the structure of a lanthanum zirconate (LZ) pyrochlore to give La2RhyZr(2 y)O(7-j,) (LRZ) to produce a strongly bound, well-dispersed metal which is active for CPOX. A second catalyst was prepared in which Sr was substituted for a portion of La in the LRZ structure, producing La(2 x)SrxRhyZr(2 y)O(7-j) (LSRZ). Each of these pyrochlore catalysts, including the unsubstituted LZ, were characterized and screened for activity in the CPOX of ntetradecane (TD), which is a surrogate for linear paraffins typical of diesel fuel. Results were compared to a commercial Rh/g-Al2O3 catalyst. X-ray diffraction patterns of both the LZ and LRZ showed that each had the cubic unit-cell pyrochlore structure. However, substitution of Sr resulted in a binary perovskite-pyrochlore phase with a defect SrZrO3 phase. Hydrogen pulse chemisorption and temperature programmed reduction studies confirmed that Rh metal was substituted into the structure of the LRZ and LSRZ, and was reducible. Activity screening with the CPOX of TD showed that the Rh substituted in both LRZ and LSRZ is able to retain activity-producing essentially equilibrium synthesis gas yields, as was the Rh/g-Al2O3. Temperature programmed oxidation experiments performed after the CPOX of TD demonstrated that the amount of carbon was quantitatively similar for each catalyst (roughly 0.3 gcarbon/gcatalyst after each run), with the exception of LSRZ, which had

  9. High-Field Magnetization of the Pyrochlore Compound Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Narumi, Yasuo; Kikkawa, Akiko; Katsumata, Koichi; Honda, Zentaro; Hagiwara, Masayuki; Kindo, Koichi

    2006-09-01

    High-field magnetization measurements have been preformed on a single crystal sample of the pyrochlore compound Gd2Ti2O7 using a pulse magnet in conjunction with a dilution refrigerator. The magnetization curve at 0.3 K reveals two magnetic phase transitions when the magnetic field is applied along b [111]. At temperatures slightly above TN, a magnetization plateau appears around 5 T and the magnetization increases again from about 15 T with a convex curvature. It is considered that this crossover is due to a competition among thermal fluctuations, short-range antiferromagnetic ordering and geometrical frustration.

  10. Magnetic resonance in the pyrochlore antiferromagnet Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Sosin, S. S.; Smirnov, A. I.; Prozorova, L. A.; Balakrishnan, G.; Zhitomirsky, M. E.

    2006-06-01

    An electron spin resonance study of frustrated pyrochlore Gd2Ti2O7 is performed in a wide frequency band for a temperature range 0.4 30K , which covers paramagnetic and magnetically ordered phases. The paramagnetic resonance reveals a spectroscopic g factor of about 2.0 and a temperature-dependent linewidth. In ordered phases magnetic resonance spectra are distinctive for a nonplanar cubic (or tetrahedral) antiferromagnet with an isotropic susceptibility. In the high-field-saturated phase, weakly dispersive soft modes are observed and their field evolution is traced.

  11. Single-ion anisotropy and transverse magnetization in the frustrated gadolinium pyrochlores

    NASA Astrophysics Data System (ADS)

    Glazkov, V. N.; Zhitomirsky, M.; Smirnov, A. I.; Marin, C.; Sanchez, J.-P.; Forget, A.; Colson, D.; Bonville, P.

    2007-04-01

    A single-ion anisotropy of the planar type is found in the pyrochlore antiferromagnet oxides Gd2M2O7 (M = Ti,Sn); its strength is comparable with the strength of the exchange coupling. Models considering the effects of the planar anisotropy predict the appearance of a transverse magnetization in an applied magnetic field. A detailed experimental study of Gd2Ti2O7 single crystals reveals that a transverse magnetization is really present at low temperatures. The magnetic phase diagram of Gd2Ti2O7 is refined.

  12. Field-driven transitions in the dipolar pyrochlore antiferromagnet Gd2Ti2O7

    NASA Astrophysics Data System (ADS)

    Cépas, Olivier; Shastry, B. Sriram

    2004-05-01

    We present a mean-field theory for magnetic-field-driven transitions in dipolar coupled gadolinium titanate Gd2Ti2O7 pyrochlore system. Low-temperature neutron scattering yields a phase that can be regarded as a eight sublattice antiferromagnet, in which long-ranged ordered moments and fluctuating moments coexist. Our theory gives parameter regions where such a phase is realized, and predicts several other phases, with transitions amongst them driven by magnetic field as well as temperature. We find several instances of local disorder parameters describing the transitions.

  13. Synthesis of (Ca,Ce3+,Ce4+)2Ti2O7: a pyrochlore with mixed-valence cerium

    NASA Astrophysics Data System (ADS)

    Garvie, Laurence A. J.; Xu, Huifang; Wang, Yifeng; Putnam, Robert L.

    2005-05-01

    Pyrochlore with mixed-valence Ce was synthesized by firing and annealing Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1300 °C. The product contains Ce-pyrochlore, Ce-rich perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) revealed both Ce4+ and Ce3+ in the Ce-pyrochlore with a Ce4+ to total Ce (Ce4+/ΣCe) of 0.80 giving (CaCe0.213+Ce0.864+)TiO. Cerium in the perovskite and cerianite is dominated by Ce3+ and Ce4+, respectively. High-resolution transmission electron microscope (HRTEM) images show that the boundary between Ce-pyrochlore and Ce-rich perovskite is semi-coherently bonded. The orientational relationship between the neighboring Ce-pyrochlore and Ce-rich perovskite is not random. Ce-pyrochlore (CaCeTi2O7) is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapons-usable Pu in geological repositories. It is postulated, based on the presence of Ce3+ in the Ce-pyrochlore, that neutron poisons such as Gd can be incorporated into the CaPuTi2O7 phase.

  14. Structure and physical properties of R2 Os2 O7 Pyrochlores

    NASA Astrophysics Data System (ADS)

    Rawl, Ryan; Calder, Stuart; Zhao, Zhiying; Zhou, Haidong; Mandrus, David; Yan, Jiaqiang

    2015-03-01

    The spin-orbit coupling (SOC) in 4d/5d transition metal oxides is enhanced to such a degree, relative to 3d oxides, that it can alter the electronic structure and have a dramatic effect on materials properties. A good example of this is the SOC assisted metal-insulator transition in Sr2IrO4, which has been extensively studied in the last few years. In a strong SOC scenario, a nonmagnetic ground state is expected for systems with d4 electronic configuration. R2Os2O7 pyrochlores, in which Os4 + has d4 electron count, provides a material playground to study the magnetism of d4 and effect of R3 +-Os4 + interplay on the ground states. This series has only undergone limited studies, with the only published data investigating the lattice parameters and electrical resistivity at room temperature. In this talk, I will report our study on the magnetic, transport, thermodynamic, and structural properties of R2Os2O7 pyrochlores. Part of the work was supported by the CEM, and NSF MRSEC, under Grant DMR-1420451.

  15. Direct Measurement of Surface Dissolution Rates in Potential Nuclear Waste Forms: The Example of Pyrochlore.

    PubMed

    Fischer, Cornelius; Finkeldei, Sarah; Brandt, Felix; Bosbach, Dirk; Luttge, Andreas

    2015-08-19

    The long-term stability of ceramic materials that are considered as potential nuclear waste forms is governed by heterogeneous surface reactivity. Thus, instead of a mean rate, the identification of one or more dominant contributors to the overall dissolution rate is the key to predict the stability of waste forms quantitatively. Direct surface measurements by vertical scanning interferometry (VSI) and their analysis via material flux maps and resulting dissolution rate spectra provide data about dominant rate contributors and their variability over time. Using pyrochlore (Nd2Zr2O7) pellet dissolution under acidic conditions as an example, we demonstrate the identification and quantification of dissolution rate contributors, based on VSI data and rate spectrum analysis. Heterogeneous surface alteration of pyrochlore varies by a factor of about 5 and additional material loss by chemo-mechanical grain pull-out within the uppermost grain layer. We identified four different rate contributors that are responsible for the observed dissolution rate range of single grains. Our new concept offers the opportunity to increase our mechanistic understanding and to predict quantitatively the alteration of ceramic waste forms.

  16. Pressure-induced phase transitions of β-type pyrochlore CsTaWO6

    DOE PAGESBeta

    Zhang, F. X.; Tracy, C. L.; Shamblin, J.; Palomares, R. I.; Lang, M.; Park, S.; Park, C.; Tkachev, S.; Ewing, R. C.

    2016-09-30

    The β-type pyrochlore CsTaWO6 was studied by synchrotron X-ray diffraction (XRD) and Raman scattering methods up to pressures of 43 GPa using a diamond anvil cell (DAC). With increasing pressure, the cubic pyrochlore in space group of Fd-3¯m with combining macron]m transforms to an orthorhombic structure (space group: Pnma) at 5.9 GPa and then to a monoclinic structure (space group: P21/c) at ~18 GPa. The structural evolution in CsTaWO6 is a continuous process and experimental results suggest that the initial cubic phase has a tetragonal distortion at ambient conditions. Both XRD and Raman measurements indicate that the pressure-induced phase transitionsmore » in CsTaWO6 are reversible. Lastly, these results may provide a structural explanation of previous experimental resistivity measurement results for the isostructural superconductor K(Cs)Os2O6 at high pressure conditions.« less

  17. Ab initio molecular dynamics simulations of ion-solid interactions in zirconate pyrochlores

    DOE PAGESBeta

    Xiao, Haiyan Y.; Weber, William J.; Zhang, Yanwen; Zu, X. T.

    2015-01-31

    In this paper, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A2Zr2O7, A = La, Nd and Sm). It shows that both cations and anions in Nd2Zr2O7 and Sm2Zr2O7 are generally more likely to be displaced than those in La2Zr2O7. The damage end states mainly consist of Frenkel pair defects, and the Frenkel pair formation energies in Nd2Zr2O7 and Sm2Zr2O7 are lower than those in La2Zr2O7. These results suggest that the order–disorder structural transition more easily occurs in Nd2Zr2O7 and Sm2Zr2O7 resulting in a defect-fluorite structure, which agrees well with experimentalmore » observations. Our calculations indicate that oxygen migration from 48f and 8b to 8a sites is dominant under low energy irradiation. A number of new defects, including four types of cation Frenkel pairs and six types of anion Frenkel pairs, are revealed by ab initio molecular dynamics simulations. The present findings may help to advance the fundamental understanding of the irradiation response behavior of zirconate pyrochlores.« less

  18. Odd-parity magnetoresistance in pyrochlore iridate thin films with broken time-reversal symmetry

    PubMed Central

    Fujita, T. C.; Kozuka, Y.; Uchida, M.; Tsukazaki, A.; Arima, T.; Kawasaki, M.

    2015-01-01

    A new class of materials termed topological insulators have been intensively investigated due to their unique Dirac surface state carrying dissipationless edge spin currents. Recently, it has been theoretically proposed that the three dimensional analogue of this type of band structure, the Weyl Semimetal phase, is materialized in pyrochlore oxides with strong spin-orbit coupling, accompanied by all-in-all-out spin ordering. Here, we report on the fabrication and magnetotransport of Eu2Ir2O7 single crystalline thin films. We reveal that one of the two degenerate all-in-all-out domain structures, which are connected by time-reversal operation, can be selectively formed by the polarity of the cooling magnetic field. Once formed, the domain is robust against an oppositely polarised magnetic field, as evidenced by an unusual odd field dependent term in the magnetoresistance and an anomalous term in the Hall resistance. Our findings pave the way for exploring the predicted novel quantum transport phenomenon at the surfaces/interfaces or magnetic domain walls of pyrochlore iridates. PMID:25959576

  19. Catalytic partial oxidation of n-tetradecane on Rh and Sr substituted pyrochlores

    SciTech Connect

    Haynes, D.J.; Berry, D.A.; Shekhawat, Dushyant; Gardner, T.H.; Spivey, J.J.

    2007-10-01

    Catalyst deactivation by high levels of sulfur and aromatics limits the catalytic partial oxidation (CPOX) of diesel fuel into a H2-rich stream for fuel cells. These species poison traditional supported metal catalysts because they adsorb strongly to electron dense metal clusters and promote the formation of carbon on the surface. In this work, Rh + Sr are substituted into lanthanum zirconate (LZ) pyrochlore (La2Zr2O7) to give an La(2-x)SrxRhyZr(2-y)O(7- î) (LSRZ) catalyst. The resistance to deactivation and carbon formation were examined by the CPOX of a mixture of 5 wt% 1-methylnaphthalene + 1000 ppmw dibenzothiophene in n-tetradecane. The results were compared to a commercial Rh/ã-Al2O3 catalyst. In the presence of these contaminants, the activity of the LSRZ was only kinetically inhibited, which is thought to be attributable to the oxygen-ion conductivity that results from Sr substitution into the pyrochlore structure. Rh/ã-Al2O3 was deactivated, likely due to significant carbon accumulation on/near the Rh metal

  20. Heavy-ion irradiation of pyrochlore oxides: Comparison between low and high energy regimes

    NASA Astrophysics Data System (ADS)

    Sattonnay, G.; Moll, S.; Thomé, L.; Legros, C.; Herbst-Ghysel, M.; Garrido, F.; Costantini, J.-M.; Trautmann, C.

    2008-06-01

    Pyrochlore pellets with Gd2(Ti2-xZrx)O7 stoichiometry were irradiated with heavy ions at energies ranging from a few MeV to a few GeV in order to compare the effects of nuclear collisions and electronic excitations. The damage created by irradiation was characterized as a function of the ion fluence by X-ray diffraction. The structural modifications induced by irradiation were shown to depend on both the sample composition and the type of irradiation. At low energy (4 MeV Au ions), the susceptibility to radiation-induced amorphization exhibits a systematic decrease with increasing Zr content. At high energy (1.5 GeV Xe or 2.6 GeV U ions), similar structural changes are observed at much lower fluences. The lattice parameter increases for low energy irradiation, particularly in the case of amorphizable pyrochlores (Gd2Ti2O7 and Gd2TiZrO7), whereas it decreases for high energy irradiation.

  1. Optical evidence for a Weyl semimetal state in pyrochlore Eu2Ir2O7

    NASA Astrophysics Data System (ADS)

    Sushkov, A. B.; Hofmann, J. B.; Jenkins, G. S.; Ishikawa, J.; Nakatsuji, S.; Das Sarma, S.; Drew, H. D.

    2015-12-01

    A Weyl semimetallic state with pairs of nondegenerate Dirac cones in three dimensions was recently predicted to occur in the antiferromagnetic state of the pyrochlore iridates. Here, we show that the THz optical conductivity and temperature dependence of the free carrier response in pyrochlore Eu2Ir2O7 match the predictions for a Weyl semimetal and suggest novel Dirac liquid behavior. The interband optical conductivity vanishes continuously at low frequencies signifying a semimetal. The metal-semimetal transition at TN=110 K is manifested in the Drude spectral weight, which is independent of temperature in the metallic phase and decreases smoothly in the ordered phase. The temperature dependence of the free carrier weight below TN is in good agreement with theoretical predictions for a Dirac material. The data yield a Fermi velocity vF≈4 ×107 cm/s, a logarithmic renormalization scale ΛL≈600 K, and require a Fermi temperature of TF≈100 K associated with residual unintentional doping to account for the low temperature optical response and dc resistivity.

  2. Optical evidence for a Weyl semimetal state in pyrochlore Eu2 Ir2 O7

    NASA Astrophysics Data System (ADS)

    Sushkov, Andrei; Hofmann, Johannes; Jenkins, Gregory; Drew, Dennis; Ishikawa, Jun; Nakatsuji, Satoru

    Possible realization of a Weyl semimetallic state with the broken time-reversal symmetry in pyrochlore iridates is still under debate. In the absense of ARPES and neutron data, optical evidence become very important. We found that the THz optical conductivity and temperature dependence of the free carrier response in pyrochlore Eu2Ir2O7 match the predictions for a Weyl semimetal and suggest novel Dirac liquid behavior. The interband optical conductivity vanishes continuously at low frequencies signifying a semimetal. The metal-semimetal transition at TN = 110 K is manifested in the Drude spectral weight, which is independent of temperature in the metallic phase, and which decreases smoothly in the ordered phase. The temperature dependence of the free carrier weight below TN is in good agreement with theoretical predictions for a Weyl semimetal. The fit of experimental Drude weight yields a Fermi velocity 4x107 cm/s, a logarithmic renormalization scale ΛL ~ 600 K, and require a Fermi temperature of 100 K associated with residual unintentional doping to account for the low temperature optical response and dc resistivity. This work was supported by Grants: NSF DMR-1104343 and 1066293, DOE ER46741-SC0005436, LPS-MPO-CMTC, the Japanese Society for the Promotion of Science R2604, and Grants-in-Aid for Scientific Research 25707030.

  3. Quantum phase transitions and anomalous Hall effect in a pyrochlore Kondo lattice

    NASA Astrophysics Data System (ADS)

    Grefe, Sarah; Ding, Wenxin; Si, Qimiao

    The metallic variant of the pyrochlore iridates Pr2Ir2O7 has shown characteristics of a possible chiral spin liquid state [PRL 96 087204 (2006), PRL 98, 057203 (2007), Nature 463, 210 (2010)] and quantum criticality [Nat. Mater. 13, 356 (2014)]. An important question surrounding the significant anomalous Hall response observed in Pr2Ir2O7 is the nature of the f-electron local moments, including their Kondo coupling with the conduction d-electrons. The heavy effective mass and related thermodynamic characteristics indicate the involvement of the Kondo effect in this system's electronic properties. In this work, we study the effects of Kondo coupling on candidate time-reversal-symmetry-breaking spin liquid states on the pyrochlore lattice. Representing the f-moments as slave fermions Kondo-coupled to conduction electrons, we study the competition between Kondo-singlet formation and chiral spin correlations and determine the zero-temperature phase diagram. We derive an effective chiral interaction between the local moments and the conduction electrons and calculate the anomalous Hall response across the quantum phase transition from the Kondo destroyed phase to the Kondo screened phase. We discuss our results' implications for Pr2Ir2O7 and related frustrated Kondo-lattice systems.

  4. Interoperability of clinical decision-support systems and electronic health records using archetypes: a case study in clinical trial eligibility.

    PubMed

    Marcos, Mar; Maldonado, Jose A; Martínez-Salvador, Begoña; Boscá, Diego; Robles, Montserrat

    2013-08-01

    Clinical decision-support systems (CDSSs) comprise systems as diverse as sophisticated platforms to store and manage clinical data, tools to alert clinicians of problematic situations, or decision-making tools to assist clinicians. Irrespective of the kind of decision-support task CDSSs should be smoothly integrated within the clinical information system, interacting with other components, in particular with the electronic health record (EHR). However, despite decades of developments, most CDSSs lack interoperability features. We deal with the interoperability problem of CDSSs and EHRs by exploiting the dual-model methodology. This methodology distinguishes a reference model and archetypes. A reference model is represented by a stable and small object-oriented model that describes the generic properties of health record information. For their part, archetypes are reusable and domain-specific definitions of clinical concepts in the form of structured and constrained combinations of the entities of the reference model. We rely on archetypes to make the CDSS compatible with EHRs from different institutions. Concretely, we use archetypes for modelling the clinical concepts that the CDSS requires, in conjunction with a series of knowledge-intensive mappings relating the archetypes to the data sources (EHR and/or other archetypes) they depend on. We introduce a comprehensive approach, including a set of tools as well as methodological guidelines, to deal with the interoperability of CDSSs and EHRs based on archetypes. Archetypes are used to build a conceptual layer of the kind of a virtual health record (VHR) over the EHR whose contents need to be integrated and used in the CDSS, associating them with structural and terminology-based semantics. Subsequently, the archetypes are mapped to the EHR by means of an expressive mapping language and specific-purpose tools. We also describe a case study where the tools and methodology have been employed in a CDSS to support

  5. Identifying and Describing Tutor Archetypes: The Pragmatist, the Architect, and the Surveyor

    ERIC Educational Resources Information Center

    Harootunian, Jeff A.; Quinn, Robert J.

    2008-01-01

    In this article, the authors identify and anecdotally describe three tutor archetypes: the pragmatist, the architect, and the surveyor. These descriptions, based on observations of remedial mathematics tutors at a land-grant university, shed light on a variety of philosophical beliefs regarding and pedagogical approaches to tutoring. An analysis…

  6. Identification of archetype and rearranged forms of BK virus in leukocytes from healthy individuals.

    PubMed

    Chatterjee, M; Weyandt, T B; Frisque, R J

    2000-03-01

    BK virus (BKV) establishes a persistent, asymptomatic infection in more than 80% of the human population, and in immunocompromised individuals BKV causes acute urinary tract infections. Two forms of BKV, archetype and rearranged, have been recovered previously from urine samples. The rearranged form is believed to have emerged from the archetype form by the deletion and duplication of sequences within the transcriptional control region (TCR). We have PCR-amplified unique rearranged forms of the BKV TCR from peripheral blood leukocytes (PBLs) of healthy donors. By employing archetype-specific PCR primers, the archetype BKV TCR was also detected in PBLs. These findings are consistent with the hypotheses that PBLs transport BKV to different sites within the body and play a role in the TCR rearrangement process. BKV sequences were detected in 21 of 38 BKV-seropositive and 1 of 2 BKV-seronegative individuals. Because of recent suggestions that SV40 may circulate in the human population, the donors' sera were also examined for the presence of specific anti-SV40 antibodies. A high antibody titer to SV40 was detected in only 1 of the 40 donor specimens. This study is the first to characterize multiple BKV TCR variants in PBLs from healthy people and to correlate PCR and serological methods used to detect BKV infections.

  7. Revisiting Teaching Archetypes: Identifying Dominant Shaping Influences on Student Teacher's Identities

    ERIC Educational Resources Information Center

    Sugrue, Ciaran

    2004-01-01

    The primary aim of this article is to identify and interrogate the lay theories of contemporary student teachers and to indicate and illustrate the manner in which these "theories" manifest both continuity and change when contrasted with teaching archetypes and previously articulated lay theories of student teachers in the setting. It is in five…

  8. Mythic-Archetypal Methods for the Language Arts. Hot Topic Guide No. 54.

    ERIC Educational Resources Information Center

    Stewart, Richard D., Comp.; Smith, Carl B., Ed.

    This "Hot Topic Guide" on mythic-archetypal methods for the language arts (which address students' inner lives to promote sharing of feelings, intuition, and imagery production in the classroom) is designed for implementation either in a workshop atmosphere or through individual study. Included are suggestions for using the guide as a professional…

  9. Feminism, Ecofeminism, and the Maternal Archetype: Motherhood as a Feminine Universal.

    ERIC Educational Resources Information Center

    Stearney, Lynn M.

    1994-01-01

    Argues that evoking the maternal archetype as a unifying principle to motivate the protection and sustenance of the environment confounds womanhood with motherhood, and fails to honor the complexity of motherhood as an ideologically and socially constructed institution. Maintains that a gender-neutral metaphor may more effectively serve both the…

  10. Neighborhood archetypes for population health research: is there no place like home?

    PubMed

    Weden, Margaret M; Bird, Chloe E; Escarce, José J; Lurie, Nicole

    2011-01-01

    This study presents a new, latent archetype approach for studying place in population health. Latent class analysis is used to show how the number, defining attributes, and change/stability of neighborhood archetypes can be characterized and tested for statistical significance. The approach is demonstrated using data on contextual determinants of health for US neighborhoods defined by census tracts in 1990 and 2000. Six archetypes (prevalence 13-20%) characterize the statistically significant combinations of contextual determinants of health from the social environment, built environment, commuting and migration patterns, and demographics and household composition of US neighborhoods. Longitudinal analyses based on the findings demonstrate notable stability (76.4% of neighborhoods categorized as the same archetype ten years later), with exceptions reflecting trends in (ex)urbanization, gentrification/downgrading, and racial/ethnic reconfiguration. The findings and approach is applicable to both research and practice (e.g. surveillance) and can be scaled up or down to study health and place in other geographical contexts or historical periods. PMID:21168356

  11. An Investigation of Mediated Person Peception Comparing Jungian Archetypes to Perception of Nonverbal Cues.

    ERIC Educational Resources Information Center

    Adams, R. C.; Copeland, Gary A.

    The effects of photographic framing on viewer perceptions of men and women was studied across five cultural groups, enabling the comparison of Jung's theory of universal archetypes to a contemporary theory of culture-bound, learned nonverbal cues. Subjects for the study were 140 college students from five cultural groups: Anglo, Chicano, Iranian,…

  12. Prejudice and Behavioral Archetypes: A New Model for Cultural-Diversity Training.

    ERIC Educational Resources Information Center

    Sussman, Lyle

    1997-01-01

    Presents a new model to help corporate cultural diversity trainers help training participants become better and more effective "citizens" in their increasingly diverse corporate cultures. Discusses why some organizational acts and actors are seen as offensive whereas others are not. Incorporates intent and style into a model with four archetypes,…

  13. American and Soviet Adolescent Archetypal Heroes of the Cold War. Professional Paper.

    ERIC Educational Resources Information Center

    Herman, William E.

    This study explores the value-oriented behaviors associated with membership in prominent youth organizations in the Soviet Union and the United States of America during the Cold War. The archetypal heroic ideals and values of the Soviet Octoberists and Pioneers and the U.S. Boy Scout and Girl Scout organizations were examined. Key political,…

  14. Teaching, Learning, and Archetypes: Images of Instruction in Cynthia Voigt's "Dicey's Song."

    ERIC Educational Resources Information Center

    Albritton, Tom

    1994-01-01

    Presents the three different types of teachers that play an important role in Cynthia Voigt's novel, "Dicey's Song." Analyzes the three models of teaching behavior represented in the novel. Relates these models to Carol Pearson's psychological archetypes for heroic growth. (HB)

  15. Validation of Minimum Data of Archetyped Telehealth Clinical Report for Monitoring Prenatal Care.

    PubMed

    Santos Alves, Danielle; Times, Valéria Cesário; de Araújo Novaes, Magdala

    2015-01-01

    Studies on the validation of minimum data sets from international information standards have drawn the attention of the academic community to the identification of necessary requirements for the development of Electronic Health Records (EHRs). The primary motivation of such studies is the development of systems using archetypes. The aim of this study was to validate the minimum data set that should be used when constructing an archetyped EHR for prenatal care applications in telehealth. In order to achieve this, a data validation tool was built and used by nine expert obstetricians. The statistical analysis employed was the percentage of agreement and the content validity index. The study was conducted in three steps: 1) Literature review, 2)Instrument development, and 3) Validation of the minimum data set. Of the 179 evaluated pieces of data, 157 of them were validated to be included in the archetyped record of the first prenatal consultation, while 56 of them were allocated for the subsequent consultation record. The benefit of this research is the standardization (data validation for an archetyped system) of prenatal care, with the perspective of employing, both nationally and internationally, an archtyped telehealth system. PMID:26262011

  16. EHR query language (EQL)--a query language for archetype-based health records.

    PubMed

    Ma, Chunlan; Frankel, Heath; Beale, Thomas; Heard, Sam

    2007-01-01

    OpenEHR specifications have been developed to standardise the representation of an international electronic health record (EHR). The language used for querying EHR data is not as yet part of the specification. To fill in this gap, Ocean Informatics has developed a query language currently known as EHR Query Language (EQL), a declarative language supporting queries on EHR data. EQL is neutral to EHR systems, programming languages and system environments and depends only on the openEHR archetype model and semantics. Thus, in principle, EQL can be used in any archetype-based computational context. In the EHR context described here, particular queries mention concepts from the openEHR EHR Reference Model (RM). EQL can be used as a common query language for disparate archetype-based applications. The use of a common RM, archetypes, and a companion query language, such as EQL, semantic interoperability of EHR information is much closer. This paper introduces the EQL syntax and provides example clinical queries to illustrate the syntax. Finally, current implementations and future directions are outlined.

  17. Achieving clinical statement interoperability using R-MIM and archetype-based semantic transformations.

    PubMed

    Kilic, Ozgur; Dogac, Asuman

    2009-07-01

    Effective use of electronic healthcare records (EHRs) has the potential to positively influence both the quality and the cost of health care. Consequently, sharing patient's EHRs is becoming a global priority in the healthcare information technology domain. This paper addresses the interoperability of EHR structure and content. It describes how two different EHR standards derived from the same reference information model (RIM) can be mapped to each other by using archetypes, refined message information model (R-MIM) derivations, and semantic tools. It is also demonstrated that well-defined R-MIM derivation rules help tracing the class properties back to their origins when the R-MIMs of two EHR standards are derived from the same RIM. Using well-defined rules also enable finding equivalences in the properties of the source and target EHRs. Yet an R-MIM still defines the concepts at the generic level. Archetypes (or templates), on the other hand, constrain an R-MIM to domain-specific concepts, and hence, provide finer granularity semantics. Therefore, while mapping clinical statements between EHRs, we also make use of the archetype semantics. Derivation statements are inferred from the Web Ontology Language definitions of the RIM, the R-MIMs, and the archetypes. Finally, we show how to transform Health Level Seven clinical statement instances to EHRcom clinical statement instances and vice versa by using the generated mapping definitions.

  18. Dealing with the Archetypes Development Process for a Regional EHR System

    PubMed Central

    Santos, M.R.; Bax, M.P.; Kalra, D.

    2012-01-01

    Objectives This paper aims to present the archetype modelling process used for the Health Department of Minas Gerais State, Brazil (SES/MG), to support building its regional EHR system, and the lessons learned during this process. Methods This study was undertaken within the Minas Gerais project. The EHR system architecture was built assuming the reference model from the ISO 13606 norm. The whole archetype development process took about ten months, coordinated by a clinical team co-ordinated by three health professionals and one systems analyst from the SES/MG. They were supported by around 30 health professionals from the internal SES/MG areas, and 5 systems analysts from the PRODEMGE. Based on a bottom-up approach, the project team used technical interviews and brainstorming sessions to conduct the modelling process. Results The main steps of the archetype modelling process were identified and described, and 20 archetypes were created. Lessons learned: –The set of principles established during the selection of PCS elements helped the clinical team to keep the focus in their objectives;–The initial focus on the archetype structural organization aspects was important;–The data elements identified were subjected to a rigorous analysis aimed at determining the most suitable clinical domain;–Levelling the concepts to accommodate them within the hierarchical levels in the reference model was definitely no easy task, and the use of a mind mapping tool facilitated the modelling process;–Part of the difficulty experienced by the clinical team was related to a view focused on the original forms previously used;–The use of worksheets facilitated the modelling process by health professionals;–It was important to have a health professional that knew about the domain tables and health classifications from the Brazilian Federal Government as member in the clinical team. Conclusion The archetypes (referencing terminology, domain tables and term lists) provided a

  19. Investigation of pyrochlore-based U-bearing ceramic nuclear waste: uranium leaching test and TEM observation.

    PubMed

    Xu, Huifang; Wang, Yifeng; Zhao, Pihong; Bourcier, William L; Van Konynenburg, Richard; Shaw, Henry F

    2004-03-01

    A durable titanate ceramic waste form (Synroc) with pyrochlore (Ca(U,Pu)Ti2O7) and zirconolite (CaZrTi2O7) as major crystalline phases has been considered to be a candidate for immobilizing various high-level wastes containing fissile elements (239Pu and 235U). Transmission electron microscopy study of a sintered ceramic with stoichiometry of Ca(U(0.5)Ce(0.25)Hf(0.25))Ti2O7 shows the material contains both pyrochlore and zirconolite phases and structural intergrowth of zirconolite lamellae within pyrochlore. The (001) plane of zirconolite is parallel to the (111) plane of pyrochlore because of their structural similarities. The pyrochlore is relatively rich in U, Ce, and Ca with respect to the coexisting zirconolite. Average compositions for the coexisting pyrochlore and zirconolite at 1350 degrees C are Ca(1.01)(Ce3+(0.13)Ce4+(0.19)U(0.52)Hf(0.18))(Ti(1.95)Hf(0.05))O7 (with U/(U + Hf) = 0.72) and (Ca(0.91)Ce(0.09))(Ce3+(0.08)U(0.26)Hf(0.66)Ti(0.01))Ti(2.00)O7 (with U/(U + Hf) = 0.28), respectively. A single pyrochlore (Ca(U,Hf)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is greater than 0.72, and a single zirconolite (Ca(Hf,U)Ti2O7) phase may be synthesized at 1350 degrees C if the ratio of U/(U + Hf) is less than 0.28. The synthesized products were used for dissolution tests. The single-pass flow-through dissolution tests show that the dissolution of the U-bearing pyrochlore is incongruent. All the elements are released at differing rates. The dissolution data also show a decrease in rate with run time. The results indicate that a diffusion-controlled process may play a key role during the release of U. TEM observation of the leached pyrochlore directly proves that an amorphous leached layer that is rich in Ti and Hf formed on the surface after the ceramic was leached in pH 4 buffered solution for 835 days. The thickness of the layer ranges from 6 to 10 nm. A nanocrystalline TiO2 phase also forms in the leached layer. The U

  20. Near-Heisenberg-limited atomic clocks in the presence of decoherence.

    PubMed

    Borregaard, J; Sørensen, A S

    2013-08-30

    The ultimate stability of atomic clocks is limited by the quantum noise of the atoms. To reduce this noise it has been suggested to use entangled atomic ensembles with reduced atomic noise. Potentially this can push the stability all the way to the limit allowed by the Heisenberg uncertainty relation, which is denoted the Heisenberg limit. In practice, however, entangled states are often more prone to decoherence, which may prevent reaching this performance. Here we present an adaptive measurement protocol that in the presence of a realistic source of decoherence enables us to get near-Heisenberg-limited stability of atomic clocks using entangled atoms. The protocol may thus realize the full potential of entanglement for quantum metrology despite the detrimental influence of decoherence.

  1. Near-Heisenberg-limited atomic clocks in the presence of decoherence.

    PubMed

    Borregaard, J; Sørensen, A S

    2013-08-30

    The ultimate stability of atomic clocks is limited by the quantum noise of the atoms. To reduce this noise it has been suggested to use entangled atomic ensembles with reduced atomic noise. Potentially this can push the stability all the way to the limit allowed by the Heisenberg uncertainty relation, which is denoted the Heisenberg limit. In practice, however, entangled states are often more prone to decoherence, which may prevent reaching this performance. Here we present an adaptive measurement protocol that in the presence of a realistic source of decoherence enables us to get near-Heisenberg-limited stability of atomic clocks using entangled atoms. The protocol may thus realize the full potential of entanglement for quantum metrology despite the detrimental influence of decoherence. PMID:24033016

  2. Experimental violation and reformulation of the Heisenberg's error-disturbance uncertainty relation

    PubMed Central

    Baek, So-Young; Kaneda, Fumihiro; Ozawa, Masanao; Edamatsu, Keiichi

    2013-01-01

    The uncertainty principle formulated by Heisenberg in 1927 describes a trade-off between the error of a measurement of one observable and the disturbance caused on another complementary observable such that their product should be no less than the limit set by Planck's constant. However, Ozawa in 1988 showed a model of position measurement that breaks Heisenberg's relation and in 2003 revealed an alternative relation for error and disturbance to be proven universally valid. Here, we report an experimental test of Ozawa's relation for a single-photon polarization qubit, exploiting a more general class of quantum measurements than the class of projective measurements. The test is carried out by linear optical devices and realizes an indirect measurement model that breaks Heisenberg's relation throughout the range of our experimental parameter and yet validates Ozawa's relation. PMID:23860715

  3. Off the Beat. An Appreciation of Werner Heisenberg and Some Talk About How Physics Was in the Good Old Days

    ERIC Educational Resources Information Center

    Thomsen, Dietrick E.

    1976-01-01

    Presented is an insight into man's idea about physics and being a physicist in the days when Heisenberg, P. A. M. Dirac, Louis de Broglic and other famous physicists were young men. Heisenberg is compared to Newton, inventing new math as he needed it. Emphasis is placed on the fact that he was not a Nazi sympathizer. (EB)

  4. Detection of archetype and rearranged variants of JC virus in multiple tissues from a pediatric PML patient.

    PubMed

    Newman, J T; Frisque, R J

    1997-07-01

    JC virus (JCV) establishes persistent infections in its human host, and in some immunocompromised individuals, the virus causes the fatal brain disease progressive multifocal leukoencephalopathy (PML). Two forms of the virus, archetype and rearranged, have been isolated, with the latter being derived from the archetype form by deletion and duplication of sequences within the viral transcriptional control region (TCR). We have used the PCR technique to amplify JCV TCR sequences present within multiple tissues of a pediatric PML patient and have cloned and sequenced the PCR products. Archetype JCV was readily detected in kidney tissue; this form of JCV was also identified for the first time in brain and lymph node tissue by employing archetype-specific PCR primers. In addition, several archetype-like variants containing small deletions within their regulatory regions were isolated from cardiac muscle and lung. Different, but related rearranged forms were detected in most of the tissue examined. Each of the rearranged TCRs lacked portions of a 66 base pair (bp) region found within the archetype promoter-enhancer but retained a 23 bp region that is deleted in the prototype (Mad 1) rearranged form of JCV. Although several rearranged forms of JCV were identified in this patient, the TCRs could be assigned to one of two groups based upon the deletion boundaries generated during the adaptation from archetype to rearranged JCV. This study is the first to characterize multiple JCV variants present in different tissues from a patient likely to have succumbed to PML during a primary infection.

  5. Sequences within the early and late promoters of archetype JC virus restrict viral DNA replication and infectivity.

    PubMed

    Daniel, A M; Swenson, J J; Mayreddy, R P; Khalili, K; Frisque, R J

    1996-02-01

    Two forms of JC virus (JCV) have been isolated from its human host, an archetype found in kidney tissue and urine of nonimmunocompromised individuals and a rearranged type detected in lymphocytes and brain tissue of patients with and without progressive multifocal leukoencephalopathy. To investigate the hypothesis that alterations to the archetype transcriptional control region yield rearranged forms of the virus exhibiting new tissue tropic and pathogenic potentials, attempts were made to propagate archetype JCV in human renal and glial cell cultures. Although rearranged forms of JCV multiplied in these cells, archetype JCV failed to do so. Through the use of chimeric and mutant viral genomes, and a cell line that constitutively expresses viral T protein, we demonstrated that archetype's inactivity relative to that of rearranged forms was due to differences in the promoter-enhancer and not in the protein coding regions or origin of DNA replication. Additional analyses revealed that the absence of a large tandem duplication and the presence of a 23- and a 66-base pair sequence in the archetype transcriptional control region were responsible for this restricted lytic behavior. We discuss the possibility that deletion and duplication events within the archetype promoter-enhancer might yield more active viral variants via the loss of a negative, or the creation of a positive, transcriptional control signal(s).

  6. Archetype JC virus efficiently replicates in COS-7 cells, simian cells constitutively expressing simian virus 40 T antigen.

    PubMed

    Hara, K; Sugimoto, C; Kitamura, T; Aoki, N; Taguchi, F; Yogo, Y

    1998-07-01

    JC polyomavirus (JCV), the causative agent of progressive multifocal leukoencephalopathy (PML), is ubiquitous in humans, infecting children asymptomatically and then persisting in the kidney. Renal JCV is not latent but replicates to excrete progeny in the urine. The renal-urinary JCV DNAs carry the archetype regulatory region that generates various rearranged regulatory regions occurring in JCVs derived from the brains of PML patients. Tissue cultures that support the efficient growth of archetype JCV have not been reported. We studied whether archetype JCV could replicate in COS-7 cells, simian cells transformed with an origin-defective mutant of simian virus 40 (SV40). Efficient JCV replication, as detected by a hemagglutination assay, was observed in cultures transfected with five of the six archetype DNAs. The progeny JCVs could be passaged to fresh COS-7 cells. However, when the parental cells of COS-7 not expressing T antigen were transfected with archetype JCV DNAs, no viral replication was detected, indicating that SV40 T antigen is essential for the growth of JCV in COS-7 cells. The archetype regulatory region was conserved during viral growth in COS-7 cells, although a small proportion of JCV DNAs underwent rearrangements outside the regulatory region. We then attempted to recover archetype JCV from urine by viral culture in COS-7 cells. Efficient JCV production was observed in COS-7 cells infected with five of the six JCV-positive urine samples examined. Thus, COS-7 cells should be of use not only for the production of archetype JCV on a large scale but also for the isolation of archetype JCV from urine.

  7. Heisenberg-limited interferometry with pair coherent states and parity measurements

    SciTech Connect

    Gerry, Christopher C.; Mimih, Jihane

    2010-07-15

    After reviewing parity-measurement-based interferometry with twin Fock states, which allows for supersensitivity (Heisenberg limited) and super-resolution, we consider interferometry with two different superpositions of twin Fock states, namely, two-mode squeezed vacuum states and pair coherent states. This study is motivated by the experimental challenge of producing twin Fock states on opposite sides of a beam splitter. We find that input two-mode squeezed states, while allowing for Heisenberg-limited sensitivity, do not yield super-resolutions, whereas both are possible with input pair coherent states.

  8. Topological triple-vortex lattice stabilized by mixed frustration in expanded honeycomb Kitaev-Heisenberg model.

    PubMed

    Yao, Xiaoyan; Dong, Shuai

    2016-01-01

    The expanded classical Kitaev-Heisenberg model on a honeycomb lattice is investigated with the next-nearest-neighboring Heisenberg interaction considered. The simulation shows a rich phase diagram with periodic behavior in a wide parameter range. Beside the double 120° ordered phase, an inhomogeneous phase is uncovered to exhibit a topological triple-vortex lattice, corresponding to the hexagonal domain structure of vector chirality, which is stabilized by the mixed frustration of two sources: the geometrical frustration arising from the lattice structure as well as the frustration from the Kitaev couplings. PMID:27229486

  9. Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment

    NASA Astrophysics Data System (ADS)

    Jeevanesan, Bhilahari; Chandra, Premala; Coleman, Piers; Orth, Peter P.

    2015-10-01

    In an extensive computational experiment, we test Polyakov's conjecture that under certain circumstances an isotropic Heisenberg model can develop algebraic spin correlations. We demonstrate the emergence of a multispin U(1) order parameter in a Heisenberg antiferromagnet on interpenetrating honeycomb and triangular lattices. The correlations of this relative phase angle are observed to decay algebraically at intermediate temperatures in an extended critical phase. Using finite-size scaling we show that both phase transitions are of the Berezinskii-Kosterlitz-Thouless type, and at lower temperatures we find long-range Z6 order.

  10. Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment.

    PubMed

    Jeevanesan, Bhilahari; Chandra, Premala; Coleman, Piers; Orth, Peter P

    2015-10-23

    In an extensive computational experiment, we test Polyakov's conjecture that under certain circumstances an isotropic Heisenberg model can develop algebraic spin correlations. We demonstrate the emergence of a multispin U(1) order parameter in a Heisenberg antiferromagnet on interpenetrating honeycomb and triangular lattices. The correlations of this relative phase angle are observed to decay algebraically at intermediate temperatures in an extended critical phase. Using finite-size scaling we show that both phase transitions are of the Berezinskii-Kosterlitz-Thouless type, and at lower temperatures we find long-range Z(6) order.

  11. Topological triple-vortex lattice stabilized by mixed frustration in expanded honeycomb Kitaev-Heisenberg model

    PubMed Central

    Yao, Xiaoyan; Dong, Shuai

    2016-01-01

    The expanded classical Kitaev-Heisenberg model on a honeycomb lattice is investigated with the next-nearest-neighboring Heisenberg interaction considered. The simulation shows a rich phase diagram with periodic behavior in a wide parameter range. Beside the double 120° ordered phase, an inhomogeneous phase is uncovered to exhibit a topological triple-vortex lattice, corresponding to the hexagonal domain structure of vector chirality, which is stabilized by the mixed frustration of two sources: the geometrical frustration arising from the lattice structure as well as the frustration from the Kitaev couplings. PMID:27229486

  12. Partition functions of classical Heisenberg spin chains with arbitrary and different exchange

    NASA Astrophysics Data System (ADS)

    Cregg, P. J.; García-Palacios, J. L.; Svedlindh, P.

    2008-10-01

    The classical Heisenberg model has been effective in modelling exchange interactions in molecular magnets. In this model, the partition function is important as it allows the calculation of the magnetization and susceptibility. For an ensemble of N-spin sites, this typically involves integrals in 2N dimensions. Here, for two-, three- and four-spin nearest neighbour open linear Heisenberg chains these integrals are reduced to sums of known functions, using a result due to Gegenbauer. For the case of the three- and four-spin chains, the sums are equivalent in form to the results of Joyce. The general result for an N-spin chain is also obtained.

  13. Long-range order for the spin-1 Heisenberg model with a small antiferromagnetic interaction

    SciTech Connect

    Lees, Benjamin

    2014-09-15

    We look at the general SU(2) invariant spin-1 Heisenberg model. This family includes the well-known Heisenberg ferromagnet and antiferromagnet as well as the interesting nematic (biquadratic) and the largely mysterious staggered-nematic interaction. Long range order is proved using the method of reflection positivity and infrared bounds on a purely nematic interaction. This is achieved through the use of a type of matrix representation of the interaction making clear several identities that would not otherwise be noticed. Using the reflection positivity of the antiferromagnetic interaction one can then show that the result is maintained if we also include an antiferromagnetic interaction that is sufficiently small.

  14. Systematic Structural Change in Selected Rare Earth Oxide Pyrochlores as Determined by Wide-Angle CBED and a Comparison with the Results of Atomistic Computer Simulation

    NASA Astrophysics Data System (ADS)

    Tabira, Yasunori; Withers, Ray L.; Minervini, Licia; Grimes, Robin W.

    2000-08-01

    An unknown oxygen atom fractional co-ordinate characteristic of the pyrochlore structure type has been determined for selected rare earth zirconate and titanate pyrochlores via a systematic row wide-angle CBED technique and shown to vary systematically with rare earth ion size. In the case of the titanate pyrochlore Gd2Ti2O7, the obtained results contrast with previously published X-ray results. Atomistic computer simulation is used to predict the value of the same parameter for a wide range of oxide pyrochlores. Comparison of calculated values with experimentally determined values shows that the general trends are correctly predicted although there appears to be systematic underestimation of both the observed values (by approximately 0.007) as well as their rate of change with rare earth ion size. Cation anti-site disorder is proposed as the origin of these discrepancies.

  15. Hydrothermal Synthesis of Lanthanide Stannates Pyrochlore Nanocrystals for Catalytic Combustion of Soot Particulates.

    PubMed

    Zhang, Xiaomin; Liu, Xuhui; Lu, Peng; Wang, Liguo; Zhang, Zhaoliang; Wang, Xiuju; Wang, Zhongpeng

    2015-01-01

    Nanocrystalline La2Sn2O7 and La2Sn1.8Co0.2O7 with a phase-pure pyrochlore structure were synthesized by a hydrothermal method, and their catalytic activity was investigated for soot combustion. The as-synthesized catalysts presented relatively larger surface area, and pore volume, which was benefit to the gas molecule diffusion in the reaction. A uniform spherical structure with particle size of 200-500 nm was found in SEM. The samples via hydrothermal route are more active for catalytic soot combustion, ascribing to the spherical morphology, high surface area and improved oxygen mobility. After Co, the reducibility was improved and surface oxygen vacancy was produced, resulting in the enhanced activity and selectivity to CO2 formation.

  16. Zirconia and Pyrochlore Oxides for Thermal Barrier Coatings in Gas Turbine Engines

    SciTech Connect

    Fergus, Jeffrey W.

    2014-04-12

    One of the important applications of yttria stabilized zirconia is as a thermal barrier coating for gas turbine engines. While yttria stabilized zirconia performs well in this function, the need for increased operating temperatures to achieve higher energy conversion efficiencies, requires the development of improved materials. To meet this challenge, some rare-earth zirconates that form the cubic fluorite derived pyrochlore structure are being developed for use in thermal barrier coatings due to their low thermal conductivity, excellent chemical stability and other suitable properties. In this paper, the thermal conductivities of current and prospective oxides for use in thermal barrier coatings are reviewed. The factors affecting the variations and differences in the thermal conductivities and the degradation behaviors of these materials are discussed.

  17. Zirconia and Pyrochlore Oxides for Thermal Barrier Coatings in Gas Turbine Engines

    DOE PAGESBeta

    Fergus, Jeffrey W.

    2014-04-12

    One of the important applications of yttria stabilized zirconia is as a thermal barrier coating for gas turbine engines. While yttria stabilized zirconia performs well in this function, the need for increased operating temperatures to achieve higher energy conversion efficiencies, requires the development of improved materials. To meet this challenge, some rare-earth zirconates that form the cubic fluorite derived pyrochlore structure are being developed for use in thermal barrier coatings due to their low thermal conductivity, excellent chemical stability and other suitable properties. In this paper, the thermal conductivities of current and prospective oxides for use in thermal barrier coatingsmore » are reviewed. The factors affecting the variations and differences in the thermal conductivities and the degradation behaviors of these materials are discussed.« less

  18. A spin-liquid with pinch-line singularities on the pyrochlore lattice

    NASA Astrophysics Data System (ADS)

    Benton, Owen; Jaubert, L. D. C.; Yan, Han; Shannon, Nic

    2016-05-01

    The mathematics of gauge theories lies behind many of the most profound advances in physics in the past 200 years, from Maxwell's theory of electromagnetism to Einstein's theory of general relativity. More recently it has become clear that gauge theories also emerge in condensed matter, a prime example being the spin-ice materials which host an emergent electromagnetic gauge field. In spin-ice, the underlying gauge structure is revealed by the presence of pinch-point singularities in neutron-scattering measurements. Here we report the discovery of a spin-liquid where the low-temperature physics is naturally described by the fluctuations of a tensor field with a continuous gauge freedom. This gauge structure underpins an unusual form of spin correlations, giving rise to pinch-line singularities: line-like analogues of the pinch points observed in spin-ice. Remarkably, these features may already have been observed in the pyrochlore material Tb2Ti2O7.

  19. Candidate quantum spin ice in the pyrochlore Pr2Hf2O7

    NASA Astrophysics Data System (ADS)

    Sibille, Romain; Lhotel, Elsa; Hatnean, Monica Ciomaga; Balakrishnan, Geetha; Fâk, Björn; Gauthier, Nicolas; Fennell, Tom; Kenzelmann, Michel

    2016-07-01

    We report the low temperature magnetic properties of the pyrochlore Pr2Hf2O7 . Polycrystalline and single-crystal samples are investigated using time-of-flight neutron spectroscopy and macroscopic measurements, respectively. The crystal-field splitting produces a non-Kramers doublet ground state for Pr3 +, with Ising-like anisotropy. Below 0.5 K ferromagnetic correlations develop, which suggests that the system enters a spin-ice-like state associated with the metamagnetic behavior observed at μ0Hc˜2.4 T. In this regime, the development of a discrete inelastic excitation in the neutron spectra indicates the appearance of spin dynamics that are likely related to cooperative quantum fluctuations.

  20. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    NASA Technical Reports Server (NTRS)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  1. The effect of electron-ion coupling on radiation damage simulations of a pyrochlore waste form.

    SciTech Connect

    Ismail, Ahmed E.; Foiles, Stephen Martin; Greathouse, Jeffery A.; Crozier, Paul Stewart

    2009-11-01

    We have performed molecular dynamics simulations of cascade damage in the gadolinium pyrochlore Gd{sub 2}Zr{sub 2}O{sub 7}, comparing results obtained from traditional methodologies that ignore the effect of electron-ion interactions with a 'two-temperature model' in which the electronic subsystem is modeled using a diffusion equation to determine the electronic temperature. We find that the electron-ion interaction friction coefficient {gamma}{sub p} is a significant parameter in determining the behavior of the system following the formation of the primary knock-on atom (here, a U{sup 3+} ion). The mean final U{sup 3+} displacement and the number of defect atoms formed is shown to decrease uniformly with increasing {gamma}{sub p}; however, other properties, such as the final equilibrium temperature and the oxygen-oxygen radial distribution function show a more complicated dependence on {gamma}{sub p}.

  2. Adiabatic demagnetization of a pyrochlore antiferromagnet Gd 2Ti 2O 7

    NASA Astrophysics Data System (ADS)

    Sosin, S. S.; Prozorova, L. A.; Smirnov, A. I.; Golov, A. I.; Berkutov, I. B.; Petrenko, O. A.; Balakrishnan, G.; Zhitomirsky, M. E.

    2005-04-01

    An adiabatic demagnetization process is studied in the pyrochlore antiferromagnet Gd2Ti2O7. A strong cooling of the sample is observed by decreasing magnetic field in the range 120-60 kOe corresponding to a crossover between saturated and spin-liquid phases. This phenomenon indicates that a considerable part of the magnetic entropy associated with a macroscopic number of local soft modes survives in the strongly correlated paramagnetic state. Monte Carlo simulations demonstrate good agreement with the experiment. The cooling power of the process is experimentally estimated with a view to possible technical applications. The results on Gd2Ti2O7 are compared to those for Gd3Ga5O12, a related material for low-temperature magnetic cooling.

  3. The oxygen positional parameter in pyrochlores and its dependence on disorder

    NASA Astrophysics Data System (ADS)

    Minervini, Licia; Grimes, Robin W.; Tabira, Yasunori; Withers, Ray L.; Sickafus, Kurt E.

    2002-01-01

    Atomistic simulation calculations based on energy minimization techniques have been used to predict the O positional parameter of a wide range of A2B2O7 pyrochlore oxides. Cations studied range from Lu3+ to La3+ on the A site and Ti4+ to Pb4+ on the B site. In all cases the model included a specific predicted degree of disorder without which it was not possible to reproduce experimental values accurately. However, the extent of disorder invoked was dependent on the specific A and B cations involved, with Gd2Ti2O7 exhibiting the lowest and Gd2Pb2O7 the highest degree of disorder.

  4. Ferroelectric studies of excessive Sm3+ containing perovskite PZT and pyrochlore biphase ceramics

    NASA Astrophysics Data System (ADS)

    Babu, T. Anil; Ramesh, K. V.; Reddy, V. Raghavendra; Sastry, D. L.

    2014-04-01

    Polycrystalline samples of Sm3+ modified Pb1-x Sm2x/3 (Zr0.6Ti0.4) O3 (PSZT) ceramics (where x = 0.1, 0.2, 0.3, 0.4) have been prepared by a high energy ball milling technique, followed by calcination at 950°C and sintering at 1150°C. As x is increased more than 0.1 mole%, considerable secondary phase has been formed. This phase has been identified as pyrochlore Sm2Ti2O7 from its X-ray diffraction (XRD) peaks. The XRD studies also indicate that the perovskte phases of the present systems undergo a dopant induced phase transformation from rhombohedral to tetragonal strucure. All the samples exhibit diffuse but non-relaxor type ferroelectric phase transition. The results of dielectric and hysteresis studies of these materials are presented.

  5. A spin-liquid with pinch-line singularities on the pyrochlore lattice.

    PubMed

    Benton, Owen; Jaubert, L D C; Yan, Han; Shannon, Nic

    2016-05-26

    The mathematics of gauge theories lies behind many of the most profound advances in physics in the past 200 years, from Maxwell's theory of electromagnetism to Einstein's theory of general relativity. More recently it has become clear that gauge theories also emerge in condensed matter, a prime example being the spin-ice materials which host an emergent electromagnetic gauge field. In spin-ice, the underlying gauge structure is revealed by the presence of pinch-point singularities in neutron-scattering measurements. Here we report the discovery of a spin-liquid where the low-temperature physics is naturally described by the fluctuations of a tensor field with a continuous gauge freedom. This gauge structure underpins an unusual form of spin correlations, giving rise to pinch-line singularities: line-like analogues of the pinch points observed in spin-ice. Remarkably, these features may already have been observed in the pyrochlore material Tb2Ti2O7.

  6. Crystal-field levels of terbium in pyrochlore compounds R2Ti2O7

    NASA Astrophysics Data System (ADS)

    Klimin, S. A.

    2015-06-01

    Temperature-dependent infrared spectroscopic study of Tb3+ f-f transitions has been performed for pyrochlore compounds Tb2Ti2O7, (Y0.99Tb0.01)2Ti2O7, and (Gd0.9Tb0.1)2Ti2O7. The peculiarities of terbium absorption were explained taking into account the presence of inversion symmetry at the rare-earth site. The energies of crystal-field levels for the ground Tb3+ multiplet were obtained. Spectral anomaly in Tb2Ti2O7 observed in the temperature range T<20 K was assigned to a strong ion-ion interaction between rare-earth ions, which leads to collective CF excitations in the terbium subsystem.

  7. The Taylor spectrum and transversality for a Heisenberg algebra of operators

    NASA Astrophysics Data System (ADS)

    Dosi, Anar A.

    2010-05-01

    A problem on noncommutative holomorphic functional calculus is considered for a Banach module over a finite-dimensional nilpotent Lie algebra. As the main result, the transversality property of algebras of noncommutative holomorphic functions with respect to the Taylor spectrum is established for a family of bounded linear operators generating a Heisenberg algebra. Bibliography: 25 titles.

  8. Phase diagrams of the Ising-Heisenberg chain with S = 1/2 triangular XXZ clusters

    SciTech Connect

    Ohanyan, V.

    2010-03-15

    The one-dimensional spin system consisted of triangular S = 1/2 XXZ Heisenberg clusters alternating with single Ising spins is considered. Partition function of the system is calculated exactly within the transfer-matrix formalism. T = 0 ground state phase diagrams, corresponding to different regions of the values of system parameters, are obtained.

  9. The Taylor spectrum and transversality for a Heisenberg algebra of operators

    SciTech Connect

    Dosi, Anar A

    2010-05-11

    A problem on noncommutative holomorphic functional calculus is considered for a Banach module over a finite-dimensional nilpotent Lie algebra. As the main result, the transversality property of algebras of noncommutative holomorphic functions with respect to the Taylor spectrum is established for a family of bounded linear operators generating a Heisenberg algebra. Bibliography: 25 titles.

  10. Heisenberg-like and Fisher-information-based uncertainty relations for N -electron d -dimensional systems

    NASA Astrophysics Data System (ADS)

    Toranzo, I. V.; López-Rosa, S.; Esquivel, R. O.; Dehesa, J. S.

    2015-06-01

    Heisenberg-like and Fisher-information-based uncertainty relations which extend and generalize previous similar expressions are obtained for N -fermion d -dimensional systems. The contributions of both spatial and spin degrees of freedom are taken into account. The accuracy of some of these generalized spinned uncertainty-like relations is numerically examined for a large number of atomic and molecular systems.

  11. Numerical calculations for Heisenberg ferromagnet on honeycomb lattice using Oguchi’s method

    SciTech Connect

    Mert, Gülistan; Mert, H. Şevki

    2015-03-10

    Magnetic properties such as the magnetization, internal energy and specific heat for Heisenberg ferromagnet with spin - 1/2 on honeycomb lattice are have been calculated using Oguchi’s method. We have found that the magnetic specific heat exhibits two peaks.

  12. Fick's law, green-kubo formula, and Heisenberg's equation of motion

    PubMed

    Lee

    2000-09-18

    Fick's law is important in transport theory and nonequilibrium statistical mechanics. The Heisenberg equation of motion for density is examined to see how it could be reduced to the diffusion equation, which is exactly equivalent to Fick's law. Conditions that are required have been noted and their implications explored.

  13. The Role of Logic and Mathematics in the Heisenberg Formulation of Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Venezia, Antonio

    2006-06-01

    In this paper, by means of a logical and linguistic analysis of Heisenberg's work, the properties of a logical model suitable for quantum mechanics are obtained. This model is an alternative to traditional quantum logic, because it uses an intuitionist negation. It is able to justify the passage from the problem of conjugate variables measurement to the mathematical formalization (commutation rules) of matrix mechanics.

  14. While Heisenberg Is Not Looking: The Strength of "Weak Measurements" in Educational Research

    ERIC Educational Resources Information Center

    Geelan, David R.

    2015-01-01

    The concept of "weak measurements" in quantum physics is a way of "cheating" the Uncertainty Principle. Heisenberg stated (and 85 years of experiments have demonstrated) that it is impossible to know both the position and momentum of a particle with arbitrary precision. More precise measurements of one decrease the precision…

  15. Quasilocal Conserved Operators in the Isotropic Heisenberg Spin-1 /2 Chain

    NASA Astrophysics Data System (ADS)

    Ilievski, Enej; Medenjak, Marko; Prosen, Tomaž

    2015-09-01

    Composing higher auxiliary-spin transfer matrices and their derivatives, we construct a family of quasilocal conserved operators of isotropic Heisenberg spin-1 /2 chain and rigorously establish their linear independence from the well-known set of local conserved charges.

  16. Studying the thermally entangled state of a three-qubit Heisenberg XX ring via quantum teleportation

    SciTech Connect

    Yeo, Ye

    2003-08-01

    We consider quantum teleportation as a tool to investigate the thermally entangled state of a three-qubit Heisenberg XX ring. Our investigation reveals interesting aspects of quantum entanglement not reflected by the pairwise thermal concurrence of the state. In particular, two mixtures of different pairs of W states, which result in the same concurrence, could yield very different average teleportation fidelities.

  17. Friction factor for turbulent flow in rough pipes from Heisenberg's closure hypothesis.

    PubMed

    Calzetta, Esteban

    2009-05-01

    We show that the main results of the analysis of the friction factor for turbulent pipe flow reported by Gioia and Chakraborty [Phys. Rev. Lett. 96, 044502 (2006)] can be recovered by assuming the Heisenberg closure hypothesis for the turbulent spectrum. This highlights the structural features of the turbulent spectrum underlying the analysis of Gioia and Chakraborty.

  18. Bismuth titanate pyrochlore microspheres: Directed synthesis and their visible light photocatalytic activity

    SciTech Connect

    Hou, Jungang; Jiao, Shuqiang; Zhu, Hongmin; Kumar, R.V.

    2011-01-15

    Bismuth titanates, Bi{sub 2}Ti{sub 2}O{sub 7} (BIT), with well-defined spherical structures were synthesized by a facile hydrothermal process without the use of any surfactant or template. XRD and SEM studies have shown that spheres could be fabricated in high yields by simply manipulating the concentrations of hydroxide ions. In this case, hydroxide ions seem to play a pivotal role in controlling the formation of seeds and growth rates of the BIT particles. On the basis of structural analysis of samples obtained at different concentrations of OH{sup -}, we also proposed a plausible mechanism to account for the formation of these distinctive morphologies under different conditions. The as-prepared BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of Rhodamine B (RhB) under visible light irradiation than that in commercial P25 TiO{sub 2}. Furthermore, the enhanced photocatalytic performance for RhB degradation was also investigated with assistance of a small amount of H{sub 2}O{sub 2}. -- Graphical abstract: Bismuth titanate pyrochlore microspheres were synthesized by a facile hydrothermal process without the use of any surfactant or template, and the effects of concentration of OH{sup -} on the diameter of microspheres, growth mechanism and photocatalytic properties were investigated. Display Omitted Research Highlights: Bismuth titanate pyrochlore microspheres with different diameters were synthesized by a facile hydrothermal process without the use of any surfactant or template. The BIT microspheres with good stability exhibited higher photocatalytic activities in the degradation of RhB under visible light irradiation than that in commercial P25 TiO{sub 2}. Further enhanced photocatalytic activity for RhB degradation was ascribed to the assistance of a small amount of H{sub 2}O{sub 2}.

  19. Structural disorder, magnetism, and electrical and thermoelectric properties of pyrochlore Nd2Ru2O7.

    PubMed

    Gaultois, Michael W; Barton, Phillip T; Birkel, Christina S; Misch, Lauren M; Rodriguez, Efrain E; Stucky, Galen D; Seshadri, Ram

    2013-05-01

    Polycrystalline Nd2Ru2O7 samples have been prepared and examined using a combination of structural, magnetic, and electrical and thermal transport studies. Analysis of synchrotron x-ray and neutron diffraction patterns suggests some site disorder on the A-site in the pyrochlore sublattice: Ru substitutes on the Nd-site up to 7.0(3)%, regardless of the different preparative conditions explored. Intrinsic magnetic and electrical transport properties have been measured. Ru 4d spins order antiferromagnetically at 143 K, as seen both in the susceptibility and in the specific heat, and there is a corresponding change in the electrical resistivity. The onset of a second antiferromagnetic ordering transition seen below 5 K is attributed to ordering of Nd 4f spins. Nd2Ru2O7 is an electrical insulator, and this behaviour is believed to be independent of the Ru-antisite disorder on the Nd-site. The electrical properties of Nd2Ru2O7 are presented in the light of data published on all A2Ru2O7 pyrochlores, and we emphasize the special structural role that Bi(3+) ions on the A-site play in driving metallic behaviour. High-temperature thermoelectric properties have also been measured. When considered in the context of known thermoelectric materials with useful figures-of-merit, it is clear that Nd2Ru2O7 has excessively high electrical resistivity which prevents it from being an effective thermoelectric. A method for screening candidate thermoelectrics is suggested.

  20. Structural and crystal chemical properties of rare-earth titanate pyrochlores

    SciTech Connect

    Farmer, James Matthew; Boatner, Lynn A; Chakoumakos, Bryan C; Du, Mao-Hua; Lance, Michael J; Rawn, Claudia J.; Bryan, Jeff C.

    2014-01-01

    Rare-earth titanates, RE2Ti2O7 (where RE = a rare-earth) with the pyrochlore structure continue to be investigated for use as potential stable host materials for nuclear and actinide-rich wastes. Accordingly, the present work is directed towards the elucidation of the fundamental structural, physical, and thermochemical properties of this class of compounds. Single-crystals of the rare earth pyrochlores were synthesized using a high-temperature flux technique and were subsequently characterized using single-crystal X-ray diffraction. The cubic lattice parameters display an approximately linear correlation with the RE-site cation radius. Theoretical calculations of the lattice constants and bond lengths of the subject materials were carried out using density functional theory, and the results are compared to the experimental values. The Sm and Eu titanates exhibit a covalency increase between the REO8 and TiO6 polyhedra resulting in a deviation from the increasing linear lattice parameter through the transition series. Gd2Ti2O7 with the 4f7 half-filled f-orbital Gd3+ sub-shell exhibits the lowest 48f oxygen positional parameter. The coefficient of thermal expansion for the rare-earth titanate series is approximately linear, and it has a range of 10.1 11.2 x 10-6 C-1. Raman spectroscopy indicated that the ~530 cm-1 peak associated with the Ti-O stretching mode follows a general trend of decreasing frequency with increasing RE reduced mass.

  1. Disordered pyrochlore CsMgInF{sub 6} at high pressures

    SciTech Connect

    Grzechnik, Andrzej; Morgenroth, Wolfgang; Friese, Karen

    2009-07-15

    High pressure behaviour of disordered pyrochlore CsMgInF{sub 6} (Pnma, Z=4) has been studied with powder and single-crystal X-ray diffraction to 8.0 and 6.94 GPa, respectively, in diamond anvil cells at room temperature. The material is structurally stable to at least 8.0 GPa with no ordering of the In{sup 3+} and Mg{sup 2+} cations. The P-V data are fitted by a Birch-Murnaghan equation of state with the zero-pressure bulk modulus B{sub 0}=33.4(3) GPa and the unit-cell volume at ambient pressure V{sub 0}=603.2(4) A{sup 3} for the first pressure derivative of the bulk modulus B'=4.00. The major contribution to the bulk compressibility arises from the changes in the coordination sphere around the Cs atoms. The effect of hydrostatic pressure on the crystal structure of CsMgInF{sub 6} is comparable to the effect of chemical pressure induced by the incorporation of ions of different sizes into the A and B sites in defect AB{sup 2+}B'{sup 3+}F{sub 6} pyrochlores. - Graphical abstract: Crystal structure of CsMgInF{sub 6} (Pnma, Z=4) at 6.04 GPa. Yellow, red, and blue symbols represent the Cs, (Mg/In), and F atoms, respectively. Octahedra around the (In1/Mg1) and (In2/Mg2) atoms are drawn gray and cyan, respectively.

  2. The 'self' in analytical psychology: the function of the 'central archetype' within Fordham's model.

    PubMed

    Urban, Elizabeth

    2008-06-01

    This paper concerns the self as Fordham came to conceive it after a conceptual analysis of Jung's use of the term. Fordham identified a contradiction in Jung's usage, and resolved it by reserving 'self' for a definition of the psychosomatic entirety of the individual, and using a separate term for referring to expressions of the self in human experience (e.g. symbols). Fordham tentatively suggested that the latter be termed the 'central archetype', although this was neither developed nor dropped. I explore the value of this term from a developmental perspective and, more specifically in terms of the deintegration of psyche out of an early psychosomatic unity. This draws upon infant research and an observation of a 14-month old boy. Finally, further developments are briefly described and illustrated, whereby pre-symbolic expressions of the central archetype become symbolic and come to reflect what was for Jung, the 'ultimate', 'Formation, Transformation, Eternal Mind's eternal recreation'.

  3. The multiplicity of dreams: cognitive-affective correlates of lucid, archetypal, and nightmare dreaming.

    PubMed

    Spadafora, A; Hunt, H T

    1990-10-01

    This preliminary research is the first to compare lucid, nightmare, and archetypal-mythological dreams on dimensions important in previous research on each. A first study of 100 subjects showed all three forms significantly correlated with each other and with estimates of dream recall. In a second study, 41 subjects were selected from the above on the basis of relative specialization in each dream form, with a control group equally high on dream recall. Here, the lucid and archetypal dreamers tended to separate themselves from nightmare sufferers on the basis of high imaginativeness, proclivity to waking mystical experience, spatial/analytic skills, and physical balance. It appears that the intensification of dreaming is expressed positively or negatively, depending on variations in these cognitive dimensions. PMID:2251094

  4. The multiplicity of dreams: cognitive-affective correlates of lucid, archetypal, and nightmare dreaming.

    PubMed

    Spadafora, A; Hunt, H T

    1990-10-01

    This preliminary research is the first to compare lucid, nightmare, and archetypal-mythological dreams on dimensions important in previous research on each. A first study of 100 subjects showed all three forms significantly correlated with each other and with estimates of dream recall. In a second study, 41 subjects were selected from the above on the basis of relative specialization in each dream form, with a control group equally high on dream recall. Here, the lucid and archetypal dreamers tended to separate themselves from nightmare sufferers on the basis of high imaginativeness, proclivity to waking mystical experience, spatial/analytic skills, and physical balance. It appears that the intensification of dreaming is expressed positively or negatively, depending on variations in these cognitive dimensions.

  5. Combining Archetypes with Fast Health Interoperability Resources in Future-proof Health Information Systems.

    PubMed

    Bosca, Diego; Moner, David; Maldonado, Jose Alberto; Robles, Montserrat

    2015-01-01

    Messaging standards, and specifically HL7 v2, are heavily used for the communication and interoperability of Health Information Systems. HL7 FHIR was created as an evolution of the messaging standards to achieve semantic interoperability. FHIR is somehow similar to other approaches like the dual model methodology as both are based on the precise modeling of clinical information. In this paper, we demonstrate how we can apply the dual model methodology to standards like FHIR. We show the usefulness of this approach for data transformation between FHIR and other specifications such as HL7 CDA, EN ISO 13606, and openEHR. We also discuss the advantages and disadvantages of defining archetypes over FHIR, and the consequences and outcomes of this approach. Finally, we exemplify this approach by creating a testing data server that supports both FHIR resources and archetypes. PMID:25991126

  6. The 'self' in analytical psychology: the function of the 'central archetype' within Fordham's model.

    PubMed

    Urban, Elizabeth

    2008-06-01

    This paper concerns the self as Fordham came to conceive it after a conceptual analysis of Jung's use of the term. Fordham identified a contradiction in Jung's usage, and resolved it by reserving 'self' for a definition of the psychosomatic entirety of the individual, and using a separate term for referring to expressions of the self in human experience (e.g. symbols). Fordham tentatively suggested that the latter be termed the 'central archetype', although this was neither developed nor dropped. I explore the value of this term from a developmental perspective and, more specifically in terms of the deintegration of psyche out of an early psychosomatic unity. This draws upon infant research and an observation of a 14-month old boy. Finally, further developments are briefly described and illustrated, whereby pre-symbolic expressions of the central archetype become symbolic and come to reflect what was for Jung, the 'ultimate', 'Formation, Transformation, Eternal Mind's eternal recreation'. PMID:18494671

  7. Housing Archetype Analysis for Home Energy-Efficient Retrofit in the Great Lakes Region

    SciTech Connect

    Kim, S. -K.; Mrozowski, T.; Harrell-Seyburn, A.; Ehrlich, N.; Hembroff, L.; Lieburn, B.; Mazor, M.; McIntyre, A.; Mutton, C.; Parsons, G.; Syal, M. G.; Wilkinson, R.

    2014-09-01

    This project report details activities and results of the "Market Characterization" project undertaken by the Cost Effective Energy Retrofit (CEER) team targeted toward the DOE goal of achieving 30%-50% reduction in existing building energy use. CEER consists of members from the Dow Chemical Company, Michigan State University, Ferris State University, and Habitat for Humanity Kent County. The purpose of this market characterization project was to identify housing archetypes which are dominant within the Great Lakes region and therefore offer significant potential for energy-efficient retrofit research and implementation due to the substantial number of homes possessing similar characteristics. Understanding the characteristics of housing groups referred to as "archetypes" by vintage, style, and construction characteristics can allow research teams to focus their retrofit research and develop prescriptive solutions for those structure types which are prevalent and offer high potential uptake within a region or market.

  8. Method to integrate clinical guidelines into the electronic health record (EHR) by applying the archetypes approach.

    PubMed

    Garcia, Diego; Moro, Claudia Maria Cabral; Cicogna, Paulo Eduardo; Carvalho, Deborah Ribeiro

    2013-01-01

    Clinical guidelines are documents that assist healthcare professionals, facilitating and standardizing diagnosis, management, and treatment in specific areas. Computerized guidelines as decision support systems (DSS) attempt to increase the performance of tasks and facilitate the use of guidelines. Most DSS are not integrated into the electronic health record (EHR), ordering some degree of rework especially related to data collection. This study's objective was to present a method for integrating clinical guidelines into the EHR. The study developed first a way to identify data and rules contained in the guidelines, and then incorporate rules into an archetype-based EHR. The proposed method tested was anemia treatment in the Chronic Kidney Disease Guideline. The phases of the method are: data and rules identification; archetypes elaboration; rules definition and inclusion in inference engine; and DSS-EHR integration and validation. The main feature of the proposed method is that it is generic and can be applied toany type of guideline. PMID:23920682

  9. Development of ISO 13606 archetypes for the standardisation of data registration in the Primary Care environment.

    PubMed

    Barros Castro, Jesús; Lamelo Alfonsín, Alejandro; Prieto Cebreiro, Javier; Rimada Mora, Dolores; Carrajo García, Lino; Vázquez González, Guillermo

    2015-01-01

    On daily procedures, companies and organizations produce a wide quantity of data. Medical information doubles every five years approximately, and most of this information has no structure and cannot be utilised. Information obtained during Primary Health Care (PC) consultations is expected to be standardized and organised following instructions made by archetype 13606 of the International Organization for Standardization (ISO) in order to guarantee the Continuity of Care as well as the potential use of these data for secondary purposes, such as investigation or statistics. This study was designed to investigate the feasibility of representing the information collected in Primary Care consultations in a structured and normalized way. A key difference to other approaches is that the intended solution is, to the best of our knowledge, the first one to register all the information collected in this area. The participation of the Primary Health Care service (PC) from Complejo Hospitalario Universitario de A Coruña (CHUAC) has been of vital importance in this project as it has provided the necessary clinical knowledge and it has allowed us to verify the effectiveness obtained in actual environments. The archetypes developed can be reused in a wide range of projects. As an example of use, we have used these archetypes to create an intelligent system that generates organised reports based on the information dictated on a medical consultation which, afterwards, can be analysed from an analytical point of view.

  10. Using community archetypes to better understand differential community adaptation to wildfire risk.

    PubMed

    Carroll, Matthew; Paveglio, Travis

    2016-06-01

    One of the immediate challenges of wildfire management concerns threats to human safety and property in residential areas adjacent to non-cultivated vegetation. One approach for relieving this problem is to increase human community 'adaptiveness' to deal with the risk and reality of fire in a variety of landscapes. The challenge in creating 'fire-adapted communities' (FACs) is the great diversity in character and make-up of populations at risk from wildfire. This paper outlines a recently developed categorization scheme for Wildland-Urban Interface (WUI) communities based on a larger conceptual approach for understanding how social diversity is likely to influence the creation of FACs. The WUI categorization scheme situates four community archetypes on a continuum that recognizes dynamic change in human community functioning. We use results from the WUI classification scheme to outline key characteristics associated with each archetype and results from recent case studies to demonstrate the diversity across WUI communities. Differences among key characteristics of local social context will likely result in the need for different adaptation strategies to wildfire. While the WUI archetypes described here may not be broadly applicable to other parts of the world, we argue that the conceptual approach and strategies for systematically documenting local influences on wildfire adaptation have potential for broad application.This article is part of the themed issue 'The interaction of fire and mankind'.

  11. Using community archetypes to better understand differential community adaptation to wildfire risk.

    PubMed

    Carroll, Matthew; Paveglio, Travis

    2016-06-01

    One of the immediate challenges of wildfire management concerns threats to human safety and property in residential areas adjacent to non-cultivated vegetation. One approach for relieving this problem is to increase human community 'adaptiveness' to deal with the risk and reality of fire in a variety of landscapes. The challenge in creating 'fire-adapted communities' (FACs) is the great diversity in character and make-up of populations at risk from wildfire. This paper outlines a recently developed categorization scheme for Wildland-Urban Interface (WUI) communities based on a larger conceptual approach for understanding how social diversity is likely to influence the creation of FACs. The WUI categorization scheme situates four community archetypes on a continuum that recognizes dynamic change in human community functioning. We use results from the WUI classification scheme to outline key characteristics associated with each archetype and results from recent case studies to demonstrate the diversity across WUI communities. Differences among key characteristics of local social context will likely result in the need for different adaptation strategies to wildfire. While the WUI archetypes described here may not be broadly applicable to other parts of the world, we argue that the conceptual approach and strategies for systematically documenting local influences on wildfire adaptation have potential for broad application.This article is part of the themed issue 'The interaction of fire and mankind'. PMID:27216514

  12. Development of ISO 13606 archetypes for the standardisation of data registration in the Primary Care environment.

    PubMed

    Barros Castro, Jesús; Lamelo Alfonsín, Alejandro; Prieto Cebreiro, Javier; Rimada Mora, Dolores; Carrajo García, Lino; Vázquez González, Guillermo

    2015-01-01

    On daily procedures, companies and organizations produce a wide quantity of data. Medical information doubles every five years approximately, and most of this information has no structure and cannot be utilised. Information obtained during Primary Health Care (PC) consultations is expected to be standardized and organised following instructions made by archetype 13606 of the International Organization for Standardization (ISO) in order to guarantee the Continuity of Care as well as the potential use of these data for secondary purposes, such as investigation or statistics. This study was designed to investigate the feasibility of representing the information collected in Primary Care consultations in a structured and normalized way. A key difference to other approaches is that the intended solution is, to the best of our knowledge, the first one to register all the information collected in this area. The participation of the Primary Health Care service (PC) from Complejo Hospitalario Universitario de A Coruña (CHUAC) has been of vital importance in this project as it has provided the necessary clinical knowledge and it has allowed us to verify the effectiveness obtained in actual environments. The archetypes developed can be reused in a wide range of projects. As an example of use, we have used these archetypes to create an intelligent system that generates organised reports based on the information dictated on a medical consultation which, afterwards, can be analysed from an analytical point of view. PMID:25991281

  13. La2Hf2O7 crystal and local structure changes on the fluorite - pyrochlore phase transition

    NASA Astrophysics Data System (ADS)

    Popov, V. V.; Menushenkov, A. P.; Yastrebtsev, A. A.; Zubavichus, Ya V.

    2016-09-01

    The process of La2Hf2O7 (rLa3+/rHf4+ = 1.63) nanocrystals formation and evolution upon calcinations up to 1400 °C has been investigated by means of synchrotron radiation X-ray diffraction (XRD) and Raman spectroscopy. It has been shown that isothermal calcination at 800 °C/3h of the X-ray amorphous precursor firstly leads to the formation of oxide nanocrystalline powders with a defect fluorite structure. In the temperature range 900 - 1000 °C we observed the nucleation and growth of pyrochlore nanodomains inside a well crystalline fluorite matrix. The pyrochlore-type superstructural ordering of cations and anions appears at calcinations temperature higher than 1000 °C.

  14. Nonequilibrium low temperature phase in pyrochlore iridate Y2Ir2O7: Possibility of glass-like dynamics

    NASA Astrophysics Data System (ADS)

    Kumar, Harish; Pramanik, A. K.

    2016-07-01

    Geometrical frustration and spin-orbit coupling effect together play vital role to influence properties in pyrochlore based iridium oxides. Here we have investigated detailed structural, magnetic, thermodynamic and transport properties of pyrochlore iridate Y2Ir2O7. Magnetization data show onset of magnetic irreversibility around temperature Tirr ∼ 160 K, however, no sign of long-range type ferromagnetic ordering is observed below Tirr. Specific heat data show no visible anomaly across Tirr, and the analysis of data indicate sizable density of states across Fermi level. Temperature dependent x-ray diffraction measurements show no change in structural symmetry down to low temperature. The material, on the other hand, shows significant relaxation and aging behavior similar to glassy dynamics. The electronic charge transport in this highly insulating system is found to follow power law dependence with temperature. The material shows negative magnetoresistance which is explained with quantum interference effect.

  15. The Strain-Driven Pyrochlore to ''Defect Fluorite'' Phase Transition in Rare Earth Sesquioxide Stabilized Cubic Zirconias

    SciTech Connect

    Tabira, Y.; Withers, R.L.; Barry, J.C.; Elcoro, L.

    2001-06-01

    The relationship between the ordering characteristic of the pyrochlore structure type and that characteristic of the ''defect fluorite'' structure type (immediately on either side of two phase regions separating the two structure types) in a range of rare earth sesquioxide-stabilized cubic zirconias was investigated by electron diffraction and imaging. Systematic structural change as a function of composition and relative size of the constituent metal ions is highlighted, and a multi-q to single-q = {1/2} [111]* model is proposed for the observed pyrochlore-to-defect fluorite phase transition. Strain introduced into the close-packed {l_brace}111{r_brace} metal ion planes of the defect fluorite average structure by the local cation and oxygen vacancy distribution is pointed to as the likely origin of the observed behavior.

  16. Ion-beam implantation and cross-sectional TEM characterization of Gd 2Ti 2O 7 pyrochlore

    NASA Astrophysics Data System (ADS)

    Lian, Jie; Wang, L. M.; Ewing, R. C.; Boatner, L. A.

    2006-01-01

    Radiation effects in a wide range of pyrochlore compositions have been extensively investigated due to the potential application of pyrochlores as host matrices for the immobilization of actinides - particularly Pu. In this study, we have performed 1.0 MeV Kr2+ ion implantations in bulk samples of single crystal Gd2Ti2O7 at room temperature at different ion fluences of 1.875, 3.125 and 5 × 1014 ions/cm2. The microstructural evolution upon ion-beam implantation was examined by cross-sectional transmission electron microscopy (TEM). The critical amorphization dose at room temperature for 1 MeV Kr2+ implanted Gd2Ti2O7 was determined to be ∼0.143 dpa, which is significantly lower than the dose obtained by ion-irradiation under in situ TEM observation.

  17. Nanocrystalline Gd₂Ti₂O₇ Pyrochlore Material for NIR Reflective Pigment Application: Micro-Structural and Optical Studies.

    PubMed

    Balamurugan, S; Dheebikha, K; Raja, T S Gokul

    2016-01-01

    In this interesting article, the synthesis of nanocrystalline Gd₂Ti₂O₇ material by ball milling followed by annealing, characterization and its application are reported. The Rietveld structural refinement data confirm the cubic pyrochlore Gd₂Ti₂O7 phase with lattice parameter, a = 1.022(9) nm. The particle size observed by HRSEM image concurs with the average crystalline sizes of particles extracted from XRD data. The optical properties of pyrochlore nanocrystalline Gd2Ti207 material are explored from UV-visible, FT-IR, NIR, PL, and Raman spectroscopic measurements. From the present investigation, it is identified that the Gd₂Ti₂O7 nanopowder may be used as solar reflective as well as color pigment due to its high NIR reflectivity (85-95%) under the wavelength of 750-2500 nm. PMID:27398507

  18. Finite-temperature scaling of spin correlations in a partially magnetized Heisenberg S =1/2 chain

    NASA Astrophysics Data System (ADS)

    Hälg, M.; Hüvonen, D.; Butch, N. P.; Demmel, F.; Zheludev, A.

    2015-09-01

    Inelastic neutron scattering is employed to study transverse spin correlations of a Heisenberg S =1 /2 chain compound in a magnetic field of 7.5 T. The target compound is the antiferromagnetic Heisenberg S =1 /2 chain material 2(1,4-dioxane).2 (H2O ).CuCl2, or CuDCl for short. The validity and the limitations of the scaling relation for the transverse dynamic structure factor are tested, discussed, and compared to the Tomonaga-Luttinger spin liquid theory and to Bethe-ansatz results for the Heisenberg model.

  19. Saturation of impurity-rich phases in a cerium-substituted pyrochlore-rich titanate ceramic: part 1 experimental results

    SciTech Connect

    Ryerson, F J; Ebbinghaus, B; Kirkorian, O; VanKonynenburg, R

    2000-05-25

    The saturation of impurity-rich accessory phases in a Ce-analog baseline ceramic formulation for the immobilization of excess plutonium has been tested by synthesizing an impurity-rich baseline compositions at 1300 C, 1350 C, and 1400 C in air. Impurity oxides are added at the 10 wt% level. The resulting phases assemblages are typically rich in pyrochlore, Hf-zirconolite (hafnolite), brannerite and rutile, but in many instances also contain an accessory mineral enriched in the impurity oxide. The concentration of that oxide in coexisting pyrochlore sets the saturation limit for solid solution of the component in question. In most cases, the accessory phase does not contain significant amounts of Ce, Gd or U. Exceptions are the stabilization of a Ca-lanthanide phosphate and a phosphate glass when P{sub 2}O{sub 5} is added to the formulation. P{sub 2}O{sub 5} addition is also very effective in reducing the modal amount of pyrochlore in the form relative to brannerite. Addition of the sodium-aluminosilicate, NaAlSiO{sub 4}, also results in the formation of a grain boundary melt at run conditions, but the fate of this phase on cooling is not well determined. At temperatures above 1300 C, addition of 10 wt% Fe{sub 2}O{sub 3} also leads to melting. Substitution of cations of different valences can also be associated with model-dependent changes in the oxidation state of uranium via charge transfer reactions. A set of simple components is suggested for the description of pyrochlores in both impurity-free and impurity-rich formulations.

  20. Pyrochlore based glass-ceramics for the immobilization of actinide-rich nuclear wastes: From concept to reality

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Zhang, Z.; Thorogood, G.; Vance, E. R.

    2013-01-01

    Pyrochlore based glass-ceramics have been developed, from concept to reality, for the immobilization of actinide-rich nuclear wastes. Compared with zirconolite based glass-ceramics, they are less sensitive to the processing redox conditions and can double actinide waste loadings thus decreasing volumes of the consolidated waste forms, and subsequently reducing the interim storage and disposal costs. More importantly, they provide an alternative flexible system to tackle radioactive wastes arising from the advanced nuclear reactors.

  1. Spin-orbit-driven magnetic structure and excitation in the 5d pyrochlore Cd2Os2O7.

    PubMed

    Calder, S; Vale, J G; Bogdanov, N A; Liu, X; Donnerer, C; Upton, M H; Casa, D; Said, A H; Lumsden, M D; Zhao, Z; Yan, J-Q; Mandrus, D; Nishimoto, S; van den Brink, J; Hill, J P; McMorrow, D F; Christianson, A D

    2016-01-01

    Much consideration has been given to the role of spin-orbit coupling (SOC) in 5d oxides, particularly on the formation of novel electronic states and manifested metal-insulator transitions (MITs). SOC plays a dominant role in 5d(5) iridates (Ir(4+)), undergoing MITs both concurrent (pyrochlores) and separated (perovskites) from the onset of magnetic order. However, the role of SOC for other 5d configurations is less clear. For example, 5d(3) (Os(5+)) systems are expected to have an orbital singlet with reduced effective SOC. The pyrochlore Cd2Os2O7 nonetheless exhibits a MIT entwined with magnetic order phenomenologically similar to pyrochlore iridates. Here, we resolve the magnetic structure in Cd2Os2O7 with neutron diffraction and then via resonant inelastic X-ray scattering determine the salient electronic and magnetic energy scales controlling the MIT. In particular, SOC plays a subtle role in creating the electronic ground state but drives the magnetic order and emergence of a multiple spin-flip magnetic excitation. PMID:27273216

  2. Spin-orbit-driven magnetic structure and excitation in the 5d pyrochlore Cd2Os2O7

    PubMed Central

    Calder, S.; Vale, J. G.; Bogdanov, N. A.; Liu, X.; Donnerer, C.; Upton, M. H.; Casa, D.; Said, A. H.; Lumsden, M. D.; Zhao, Z.; Yan, J. -Q.; Mandrus, D.; Nishimoto, S.; van den Brink, J.; Hill, J. P.; McMorrow, D. F.; Christianson, A. D.

    2016-01-01

    Much consideration has been given to the role of spin-orbit coupling (SOC) in 5d oxides, particularly on the formation of novel electronic states and manifested metal-insulator transitions (MITs). SOC plays a dominant role in 5d5 iridates (Ir4+), undergoing MITs both concurrent (pyrochlores) and separated (perovskites) from the onset of magnetic order. However, the role of SOC for other 5d configurations is less clear. For example, 5d3 (Os5+) systems are expected to have an orbital singlet with reduced effective SOC. The pyrochlore Cd2Os2O7 nonetheless exhibits a MIT entwined with magnetic order phenomenologically similar to pyrochlore iridates. Here, we resolve the magnetic structure in Cd2Os2O7 with neutron diffraction and then via resonant inelastic X-ray scattering determine the salient electronic and magnetic energy scales controlling the MIT. In particular, SOC plays a subtle role in creating the electronic ground state but drives the magnetic order and emergence of a multiple spin-flip magnetic excitation. PMID:27273216

  3. Spin-orbit-driven magnetic structure and excitation in the 5d pyrochlore Cd2Os2O7

    NASA Astrophysics Data System (ADS)

    Calder, S.; Vale, J. G.; Bogdanov, N. A.; Liu, X.; Donnerer, C.; Upton, M. H.; Casa, D.; Said, A. H.; Lumsden, M. D.; Zhao, Z.; Yan, J.-Q.; Mandrus, D.; Nishimoto, S.; van den Brink, J.; Hill, J. P.; McMorrow, D. F.; Christianson, A. D.

    2016-06-01

    Much consideration has been given to the role of spin-orbit coupling (SOC) in 5d oxides, particularly on the formation of novel electronic states and manifested metal-insulator transitions (MITs). SOC plays a dominant role in 5d5 iridates (Ir4+), undergoing MITs both concurrent (pyrochlores) and separated (perovskites) from the onset of magnetic order. However, the role of SOC for other 5d configurations is less clear. For example, 5d3 (Os5+) systems are expected to have an orbital singlet with reduced effective SOC. The pyrochlore Cd2Os2O7 nonetheless exhibits a MIT entwined with magnetic order phenomenologically similar to pyrochlore iridates. Here, we resolve the magnetic structure in Cd2Os2O7 with neutron diffraction and then via resonant inelastic X-ray scattering determine the salient electronic and magnetic energy scales controlling the MIT. In particular, SOC plays a subtle role in creating the electronic ground state but drives the magnetic order and emergence of a multiple spin-flip magnetic excitation.

  4. Epitaxial crystals of Bi₂Pt₂O₇ pyrochlore through the transformation of δ–Bi₂O₃ fluorite

    SciTech Connect

    Gutiérrez–Llorente, Araceli; Joress, Howie; Woll, Arthur; Holtz, Megan E.; Ward, Matthew J.; Sullivan, Matthew C.; Muller, David A.; Brock, Joel D.

    2015-03-01

    Bi₂Pt₂O₇ pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi₂Pt₂O₇ has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt⁴⁺. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi₂O₃ and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi₂Pt₂O₇. We also visualized the pyrochlore structure by scanning transmission electron microscopy, and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the δ–Bi₂O₃ and Bi₂Pt₂O₇ structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi₂Pt₂O₇.

  5. Epitaxial crystals of Bi₂Pt₂O₇ pyrochlore through the transformation of δ–Bi₂O₃ fluorite

    DOE PAGESBeta

    Gutiérrez–Llorente, Araceli; Joress, Howie; Woll, Arthur; Holtz, Megan E.; Ward, Matthew J.; Sullivan, Matthew C.; Muller, David A.; Brock, Joel D.

    2015-03-01

    Bi₂Pt₂O₇ pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi₂Pt₂O₇ has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt⁴⁺. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi₂O₃ and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi₂Pt₂O₇. We also visualized the pyrochlore structure by scanning transmission electron microscopy,more » and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the δ–Bi₂O₃ and Bi₂Pt₂O₇ structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi₂Pt₂O₇.« less

  6. Novel ruthenium pyrochlore materials for cathode application in intermediate temperature solid oxide fuel cells (IT-SOFCs)

    NASA Astrophysics Data System (ADS)

    Abate, Chiara

    The performance of solid oxide fuel cells, which operate in the temperature range of 500- 700°C (IT-SOFCs), strongly depends on the cathode employed because the interfacial polarization increases rapidly with decreasing temperature. Pyrochlore oxides with Ru on the B-site of the crystal lattice have been shown to have excellent electro catalytic behaviour for oxygen reduction reaction and high electrical conductivity. These characteristics make pyrochlore ruthenates good candidates for IT-SOFCs cathodes. In this work, several compositions of Y2-xPrxRu 2O7 (x = 0, 0.2, 0.5, 1, 1.5, 2) pyrochlore powders were prepared by a soft precipitation method. All the synthesized powders were single pyrochlore phase with particles size depending on the material compositions. Praseodymium (Pr) was introduced in the A-site with the intent to improve the material electrical proprieties and consequently the overall cathode performance. In fact, without destabilizing the pyrochlore structure, Pr caused structural changes that allow higher electron mobility. The electrical measurements showed that the electrical conductivity of the material increased with increasing the Pr content. Compositions of Y2-xPrxRu2O7 were tested as a cathode to compare its electro-catalytic effect with either of two electrolytes, gadolinium doped ceria (GDC) or erbium stabilized bismuth oxide (ESB). Both systems, Y2-xPrxRu2O 7/ESB and Y2-xPrxRu2O7/GDC, showed a similar variation of the electrode area specific resistance (ASR) with Pr content. This trend was shown to be due to a change of the cathode microstructure upon increasing Pr content. The 25 mol % Pr cathode material on ESB electrolyte presented the best performance. A change of ASR as a function of oxygen partial pressure suggested that the oxygen diffusion is the limiting step of the electrode kinetics. Hence, the better cathode performance on ESB resulted from a much lower charge transfer resistance compared to the GDC system. A partial solid

  7. Why it is difficult to see the anima as a helpful object: critique and clinical relevance of the theory of archetypes.

    PubMed

    von Raffay, A

    2000-10-01

    This paper is divided into three parts. The first deals briefly with more general aspects of the theory of archetypes (as conceived by Jung); the second examines the anima archetype in rather more detail, because it is, apart from the self, the main archetype in Jung's thought; and the third discusses the clinical repercussions of the anima theory and of the theory of the archetypes in general. The various references to Jung himself and certain circumstances of his life are included here on the assumption that personal problems in his biography contributed decisively to the constitution of his theory, so that deeper insights accure if they are taken into account.

  8. Why it is difficult to see the anima as a helpful object: critique and clinical relevance of the theory of archetypes.

    PubMed

    von Raffay, A

    2000-10-01

    This paper is divided into three parts. The first deals briefly with more general aspects of the theory of archetypes (as conceived by Jung); the second examines the anima archetype in rather more detail, because it is, apart from the self, the main archetype in Jung's thought; and the third discusses the clinical repercussions of the anima theory and of the theory of the archetypes in general. The various references to Jung himself and certain circumstances of his life are included here on the assumption that personal problems in his biography contributed decisively to the constitution of his theory, so that deeper insights accure if they are taken into account. PMID:11077760

  9. Predictions of thermal expansion coefficients of rare-earth zirconate pyrochlores: A quasi-harmonic approximation based on stable phonon modes

    NASA Astrophysics Data System (ADS)

    Lan, Guoqiang; Ouyang, Bin; Xu, Yushuai; Song, Jun; Jiang, Yong

    2016-06-01

    Rare-earth (RE) pyrochlores are considered as promising candidate materials for the thermal barrier coating. In this study, we performed first-principles calculations, augmented by quasi-harmonic phonon calculations, to investigate the thermal expansion behaviors of several RE2Zr2O7 (RE = La, Nd, Sm, Gd) pyrochlores. Our findings show that RE2Zr2O7 pyrochlores exhibit low-lying optical phonon frequencies that correspond to RE-cation rattling vibrational modes. These frequencies become imaginary upon volume expansion, preventing correct determination of the free energy versus volume relation and thereby quantification of thermal expansion using QH phonon calculations. To address this challenge, we proposed a QH approximation approach based on stable phonon modes where the RE-cation rattling modes were systematically eliminated. This approach is shown to provide accurate predictions of the coefficients of thermal expansion (CTEs) of RE2Zr2O7 pyrochlores, in good agreement with experimental measurements and data from first-principles molecular dynamics simulations. In addition, we showed that the QH Debye model considerably overestimates the magnitudes and wrongly predicts the trend for the CTEs of RE2Zr2O7 pyrochlores.

  10. Fabrication and Properties of Technetium-Bearing Pyrochlores and Perovskites as Potential Waste Forms - 13222

    SciTech Connect

    Hartmann, Thomas; Alaniz, Ariana J.; Antonio, Daniel J.

    2013-07-01

    Technetium-99 (t{sub 1/2}= 2.13x10{sup 5} years) is important from a nuclear waste perspective and is one of the most abundant, long-lived radioisotopes in used nuclear fuel (UNF). As such, it is targeted in UNF separation strategies such as UREX+, for isolation and encapsulation in solid waste forms for storage in a nuclear repository. We report here results regarding the incorporation of Tc-99 into ternary oxides of different structure types: pyrochlore (Nd{sub 2}Tc{sub 2}O{sub 7}), perovskite (SrTcO{sub 3}), and layered perovskite (Sr{sub 2}TcO{sub 4}). The goal was to determine synthesis conditions of these potential waste forms to immobilize Tc-99 as tetravalent technetium and to harvest crystallographic, thermophysical and hydrodynamic data. The objective of this research is to provide fundamental crystallographic and thermophysical data on advanced ceramic Tc-99 waste forms such as pyrochlore, perovskite, and layered perovskite in support of our current efforts on the corrosion of technetium-bearing waste forms. The ceramic Tc-99-bearing waste forms exhibit good crystallinity. The lattice parameters and crystal structures of the technetium host phases could be refined with high accuracies of ±3, ±4, and ±7 fm (10{sup -15} m), for Nd{sub 2}Tc{sub 2}O{sub 7}, SrTcO{sub 3}, and Sr{sub 2}TcO{sub 4}, respectively. The associated refinement residuals (R{sub Wp}) for the patterns are 4.1 %, 4.7 % and 6.7 %, and the refinement residuals for the individual phases (R{sub Bragg}) are 2.0 %, 2.4 % and 3.9 %, respectively. Thermophysical properties of the oxides SrTcO{sub 3}, Sr{sub 2}TcO{sub 4}, and Nd{sub 2}Tc{sub 2}O{sub 7} were analyzed using AC magnetic susceptibility measurements to further harvest information on the critical temperature (T{sub c}) for superconductivity. In our experiments the strontium technetates, SrTcO{sub 3} and Sr{sub 2}TcO{sub 4}, show superconductivity at rather high critical temperatures of T{sub c} = 7.8 K and 7 K, respectively. On the

  11. Catalytic partial oxidation of n-tetradecane using Rh and Sr substituted pyrochlores: Effects of sulfur

    SciTech Connect

    Haynes, D.; Berry, D.; Shekhawat, D. Spivey, J.

    2009-01-01

    The presence of high levels of organosulfur compounds hinders the catalytic partial oxidation (CPOX) of logistic fuels into a H2-rich gas stream for fuel cells. These species poison traditional supported metal catalysts because the sulfur adsorbs strongly to electron dense metal clusters and promotes the formation of carbon on the surface. To minimize deactivation by sulfur, two substituted lanthanum zirconate (LZ) pyrochlores (La2Zr2O7), identified in a previous study [D.J. Haynes, D.A. Berry, D. Shekhawat, J.J. Spivey, Catal. Today 136 (2008) 206], were investigated: (a) La–Rh–Zr (LRZ) and La–Sr– Rh–Zr (LSRZ). Using unsubstituted lanthanum zirconate and a conventional 0.5 wt% Rh/g-Al2O3 as comparisons, these four catalysts were exposed to a feed containing 1000 ppmw dibenzothiophene (DBT) in n-tetradecane (TD). DBT rapidly deactivated both the 0.5 wt% Rh/g-Al2O3 and LZ. The LRZ catalyst experienced a gradual deactivation, suggesting that Rh substitution into the pyrochlore structure, by itself, cannot completely eliminate deactivation by sulfur. However, the additional substitution of Sr stabilized yields of H2 and CO in the presence of DBT at levels only slightly below those observed without sulfur in the feed. After sulfur was removed from the feed, each catalyst was able to recover some activity. The recovery appears to be linked to carbon formed on active sites. The 0.5 wt% Rh/g-Al2O3, LZ, and LRZ all had comparable amounts of carbon formed on the surface: 0.90, 0.80 and 0.86 gcarbon/gcat, respectively. Of these three catalysts, only the LRZ was able to recover a significant portion of initial activity, suggesting that the carbon formed indiscriminately on the surface, and not solely on the active sites. LSRZ was able to regain almost its initial activity once sulfur was removed from the feed, and had the least amount of carbon on the surface (0.30 gcarbon/gcat). It is hypothesized that oxygen-ion mobility, which results from Sr substitution

  12. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet

    DOE PAGESBeta

    Fu, Mingxuan; Imai, Takahashi; Han, Tian -Heng; Lee, Young S.

    2015-11-06

    Here, the kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χkagome, deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with themore » magnetic field dependence of χkagome that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap.« less

  13. Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet.

    PubMed

    Fu, Mingxuan; Imai, Takashi; Han, Tian-Heng; Lee, Young S

    2015-11-01

    The kagome Heisenberg antiferromagnet is a leading candidate in the search for a spin system with a quantum spin-liquid ground state. The nature of its ground state remains a matter of active debate. We conducted oxygen-17 single-crystal nuclear magnetic resonance (NMR) measurements of the spin-1/2 kagome lattice in herbertsmithite [ZnCu3(OH)6Cl2], which is known to exhibit a spinon continuum in the spin excitation spectrum. We demonstrated that the intrinsic local spin susceptibility χ(kagome), deduced from the oxygen-17 NMR frequency shift, asymptotes to zero below temperatures of 0.03J, where J ~ 200 kelvin is the copper-copper superexchange interaction. Combined with the magnetic field dependence of χ(kagome) that we observed at low temperatures, these results imply that the kagome Heisenberg antiferromagnet has a spin-liquid ground state with a finite gap. PMID:26542565

  14. High Field Magnetization Studies of Low Dimensional Heisenberg S = 1/2 Antiferromagnets

    NASA Astrophysics Data System (ADS)

    Landee, C. P.; Albrecht, A. S.; Turnbull, M. M.

    1997-03-01

    The magnetization curves of a number of new 2D S=1/2 Heisenberg antiferromagnets have been determined in fields up to 30 tesla at low temperatures at the National High Magnetic Fields Laboratory. Magnets studied include (2-amino-5-methylpyridinium)_2CuBr4 (2-amino-5-chloropyridinium)_2CuBr_4, and [Cu(pz)_2(NO_3)](PF_6), where pz = pyrazine. All of the magnetization curves show upward curvature, a previously unknown effect for this model system. The magnetization curves are qualitatively similar to the theoretical prediction for the linear chain Heisenberg antiferromagnet. The saturation fields are consistent with those predicted from a molecular-field model, using exchange strengths obtained from susceptibility studies. Slight anisotropy has been observed in the single crystal studies of (2-amino-5-methylpyridinium)_2CuBr_4.

  15. Observability, Anschaulichkeit and Abstraction: A Journey into Werner Heisenberg's Science and Philosophy

    NASA Astrophysics Data System (ADS)

    Lacki, Jan

    2003-09-01

    Werner Heisenberg was one of the greatest physicists of the 20th century. He participated as a front rank actor in the shaping of a good part of XXth century physics and directly witnessed most of the intellectual struggles which led to what he called “Wandlungen in den Grundlagen der exakten Naturwissenschaft”. This expression is borrowed from one of the many talks and writings he devoted to the analysis of the scientific and philosophical implications of his, and his fellows physicists, findings. Indeed, Heisenberg's scientific activity increasingly reflected his more general intellectual views. This makes him another magnificent representative of a glorious linage going from the remote times of modern science to Einstein, Bohr and the like. This “philosophical” vein started early in his scientific life, and got stronger with time, prompted by the highly demanding scientific, but also social and political context of his mature years.

  16. Exactly solved mixed spin-(1,1/2) Ising-Heisenberg distorted diamond chain

    NASA Astrophysics Data System (ADS)

    Lisnyi, Bohdan; Strečka, Jozef

    2016-11-01

    The mixed spin-(1,1/2) Ising-Heisenberg model on a distorted diamond chain with the spin-1 nodal atoms and the spin-1/2 interstitial atoms is exactly solved by the transfer-matrix method. An influence of the geometric spin frustration and the parallelogram distortion on the ground state, magnetization, susceptibility and specific heat of the mixed-spin Ising-Heisenberg distorted diamond chain are investigated in detail. It is demonstrated that the zero-temperature magnetization curve may involve intermediate plateaus just at zero and one-half of the saturation magnetization. The temperature dependence of the specific heat may have up to three distinct peaks at zero magnetic field and up to four distinct peaks at a non-zero magnetic field. The origin of multipeak thermal behavior of the specific heat is comprehensively studied.

  17. Three-qubit thermal entanglement via entanglement swapping on two-qubit Heisenberg XY chains

    SciTech Connect

    Kao, Zi Chong; Ng, Jezreel; Yeo, Ye

    2005-12-15

    In this paper, we consider the generation of a three-qubit Greenberger-Horne-Zeilinger-like thermal state by applying the entanglement swapping scheme of Zukowski et al. [Ann. N. Y. Acad. Sci. 755, 91 (1995)] to three pairs of two-qubit Heisenberg XY chains. The quality of the resulting three-qubit entanglement is studied by analyzing the teleportation fidelity, when it is used as a resource in the teleportation protocol of Karlsson et al. [Phys. Rev. A 58, 4394 (1998)]. We show that even though thermal noise in the original two-qubit states is amplified by the entanglement swapping process, we are still able to achieve nonclassical fidelities for the anisotropic Heisenberg XY chains at finitely higher and higher temperatures by adjusting the strengths of an external magnetic field. This has a positive implication on the solid-state realization of a quantum computer.

  18. Nontrivial ferrimagnetism of the Heisenberg model on the Union Jack strip lattice

    NASA Astrophysics Data System (ADS)

    Shimokawa, Tokuro; Nakano, Hiroki

    2013-08-01

    We study the ground-state properties of the S = 1/2 antiferromagnetic Heisenberg model on the Union Jack strip lattice by using the exact-diagonalization and density matrix renormalization group methods. We confirm a region of a magnetization state intermediate between the Néel-like spin liquid state and the conventional ferrimagnetic state of a Lieb-Mattis type. In the intermediate state, we find that the spontaneous magnetization changes gradually with respect to the strength of the inner interaction. In addition, the local magnetization clearly shows an incommensurate modulation with long-distance periodicity in the intermediate magnetization state. These characteristic behaviors lead to the conclusion that the intermediate magnetization state is a non-Lieb-Mattis ferrimagnetic one. We also discuss the relationship between the ground-state properties of the S = 1/2 antiferromagnetic Heisenberg model on the original Union Jack lattice and those on our strip lattice.

  19. Zigzag order and phase competition in expanded Kitaev-Heisenberg model on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Yao, Xiaoyan

    2015-07-01

    The Kitaev-Heisenberg model on the honeycomb lattice is investigated in two cases: (I) with the Kitaev interaction between the nearest neighbors, and (II) with the Kitaev interaction between the next nearest neighbors. In the full parameter range, the ground states are searched by Monte Carlo simulation and identified by evaluating the correlation functions. The energies of different phases are calculated and compared with the simulated result to show the phase competition. It is observed from both energy calculation and the density of states that the zigzag order shows a symmetric behavior to the stripy phase in the pure Kitaev-Heisenberg model. By considering more interactions in both cases, the energy of zigzag order can be reduced lower than the energies of other states. Thus the zigzag phase may be stabilized in more parameter region and even extended to the whole parameter range.

  20. Aharonov-Bohm effect in quantum-to-classical correspondence of the Heisenberg principle

    SciTech Connect

    Lin, D.-H.; Chang, J.-G.; Hwang, C.-C.

    2003-04-01

    The exact energy spectrum and wave function of a charged particle moving in the Coulomb field and Aharonov-Bohm's magnetic flux are solved by the nonintegrable phase factor. The universal formula for the matrix elements of the radial operator r{sup {alpha}} of arbitrary power {alpha} is given by an analytical solution. The difference between the classical limit of matrix elements of inverse radius in quantum mechanics and the Fourier components of the corresponding quantity for the pure Coulomb system in classical mechanics is examined in reference to the correspondence principle of Heisenberg. Explicit calculation shows that the influence of nonlocal Aharonov-Bohm effect exists even in the classical limit. The semiclassical quantization rule for systems containing the topological effect is presented in the light of Heisenberg's corresponding principle.

  1. A nonlinear lattice model for Heisenberg helimagnet and spin wave instabilities

    NASA Astrophysics Data System (ADS)

    Ludvin Felcy, A.; Latha, M. M.; Christal Vasanthi, C.

    2016-10-01

    We study the dynamics of a Heisenberg helimagnet by presenting a square lattice model and proposing the Hamiltonian associated with it. The corresponding equation of motion is constructed after averaging the Hamiltonian using a suitable wavefunction. The stability of the spin wave is discussed by means of Modulational Instability (MI) analysis. The influence of various types of inhomogeneities in the lattice is also investigated by improving the model.

  2. String limit of the isotropic Heisenberg chain in the four-particle sector

    SciTech Connect

    Antipov, A. G. Komarov, I. V.

    2008-05-15

    The quantum method of variable separation is applied to the spectral problem of the isotropic Heisenberg model. The Baxter difference equation is resolved by means of a special quasiclassical asymptotic expansion. States are identified by multiplicities of limiting values of the Bethe parameters. The string limit of the four-particle sector is investigated. String solutions are singled out and classified. It is shown that only a minor fraction of solutions demonstrate string behavior.

  3. Chiral-glass transition in a diluted dipolar-interaction Heisenberg system

    NASA Astrophysics Data System (ADS)

    Zhang, Kai-Cheng; Liu, Gui-Bin; Zhu, Yan

    2011-05-01

    Recently, numerical simulations reveal that a spin-glass transition can occur in the three-dimensional diluted dipolar system. By defining the chirality of triple spins in a diluted dipolar Heisenberg spin glass, we study the chiral ordering in the system using parallel tempering algorithm and heat bath method. The finite-size scaling analysis reveals that the system undergoes a chiral-glass transition at finite temperature.

  4. An introduction to the spectrum, symmetries, and dynamics of spin-1/2 Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Joel, Kira; Kollmar, Davida; Santos, Lea F.

    2013-06-01

    Quantum spin chains are prototype quantum many-body systems that are employed in the description of various complex physical phenomena. We provide an introduction to this subject by focusing on the time evolution of a Heisenberg spin-1/2 chain and interpreting the results based on the analysis of the eigenvalues, eigenstates, and symmetries of the system. We make available online all computer codes used to obtain our data.

  5. Topological basis realization for BMW algebra and Heisenberg XXZ spin chain model

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Xue, Kang; Wang, Gangcheng; Liu, Ying; Sun, Chunfang

    2015-04-01

    In this paper, we study three-dimensional (3D) reduced Birman-Murakami-Wenzl (BMW) algebra based on topological basis theory. Several examples of BMW algebra representations are reviewed. We also discuss a special solution of BMW algebra, which can be used to construct Heisenberg XXZ model. The theory of topological basis provides a useful method to solve quantum spin chain models. It is also shown that the ground state of XXZ spin chain is superposition state of topological basis.

  6. Correlation functions of the antiferromagnetic Heisenberg model using a modified Lanczos method

    NASA Astrophysics Data System (ADS)

    Gagliano, Eduardo R.; Dagotto, Elbio; Moreo, Adriana; Alcaraz, Francisco C.

    1986-08-01

    Using a modified Lanczos algorithm, we study the correlation functions in the ground state of the one-dimensional antiferromagnetic Heisenberg model. We obtain numerical results for rings up to 24 sites. There are no indications of the anomalous behavior of these correlation functions recently observed in chains with 16 sites. We also present a pedagogical description of the hashing technique which is an efficient algorithm for searching and storage purposes.

  7. Heat kernel asymptotic expansions for the Heisenberg sub-Laplacian and the Grushin operator

    PubMed Central

    Chang, Der-Chen; Li, Yutian

    2015-01-01

    The sub-Laplacian on the Heisenberg group and the Grushin operator are typical examples of sub-elliptic operators. Their heat kernels are both given in the form of Laplace-type integrals. By using Laplace's method, the method of stationary phase and the method of steepest descent, we derive the small-time asymptotic expansions for these heat kernels, which are related to the geodesic structure of the induced geometries. PMID:25792966

  8. Teleportation via thermally entangled states of a two-qubit Heisenberg XX chain

    SciTech Connect

    Yeo Ye

    2002-12-01

    Recently, entanglement teleportation has been investigated by Lee and Kim [Phys. Rev. Lett. 84, 4236 (2000)]. In this paper we study entanglement teleportation via two separate thermally entangled states of a two-qubit Heisenberg XX chain. We established the condition under which the parameters of the model have to satisfy in order to teleport entanglement. The necessary minimum amount of thermal entanglement for some fixed strength of exchange coupling is a function of the magnetic field and the temperature.

  9. Heisenberg Uncertainty and the Allowable Masses of the Up Quark and Down Quark

    NASA Astrophysics Data System (ADS)

    Orr, Brian

    2004-05-01

    A possible explanation for the inability to attain deterministic measurements of an elementary particle's energy, as given by the Heisenberg Uncertainty Principle, manifests itself in an interesting anthropic consequent of Andrei Linde's Self-reproducing Inflationary Multiverse model. In Linde's model, the physical laws and constants that govern our universe adopt other values in other universes, due to variable Higgs fields. While the physics in our universe allow for the advent of life and consciousness, the physics necessary for life are not likely to exist in other universes -- Linde demonstrates this through a kind of Darwinism for universes. Our universe, then, is unique. But what are the physical laws and constants that make our universe what it is? Craig Hogan identifies five physical constants that are not bound by symmetry. Fine-tuning these constants gives rise to the basic behavior and structures of the universe. Three of the non-symmetric constants are fermion masses: the up quark mass, the down quark mass, and the electron mass. I will explore Linde's and Hogan's works by comparing the amount of uncertainty in quark masses, as calculated from the Heisenberg Uncertainty Principle, to the range of quark mass values consistent with our observed universe. Should the fine-tuning of the up quark and down quark masses be greater than the range of Heisenberg uncertainties in their respective masses (as I predict, due to quantum tunneling), then perhaps there is a correlation between the measured Heisenberg uncertainty in quark masses and the fine-tuning of masses required for our universe to be as it is. Hogan; "Why the Universe is Just So;" Reviews of Modern Physics; Issue 4; Vol. 72; pg. 1149-1161; Oct. 2000 Linde, "The Self-Reproducing Inflationary Universe;" Scientific American; No. 5; Vol. 271; pg. 48-55; Nov. 1994

  10. Extension of Lieb-Schupp theorem to Heisenberg models with higher-order interactions

    NASA Astrophysics Data System (ADS)

    Tanaka, Kengo

    2016-10-01

    We extend the Lieb-Schupp theorem to Heisenberg models with higher-order interactions on nonfrustrated or frustrated finite lattices. These lattices are constructed by even-numbered rings with or without crossing bonds and have reflection symmetry. The results show that the ground state has total spin zero in wide interaction parameter regions which are not covered by the results of Marshall-Lieb-Mattis-type arguments.

  11. A discussion on the Heisenberg uncertainty principle from the perspective of special relativity

    NASA Astrophysics Data System (ADS)

    Nanni, Luca

    2016-09-01

    In this note, we consider the implications of the Heisenberg uncertainty principle (HUP) when computing uncertainties that affect the main dynamical quantities, from the perspective of special relativity. Using the well-known formula for propagating statistical errors, we prove that the uncertainty relations between the moduli of conjugate observables are not relativistically invariant. The new relationships show that, in experiments involving relativistic particles, limitations of the precision of a quantity obtained by indirect calculations may affect the final result.

  12. Genome wide expression profiling of angiogenic signaling and the Heisenberg uncertainty principle.

    PubMed

    Huber, Peter E; Hauser, Kai; Abdollahi, Amir

    2004-11-01

    Genome wide DNA expression profiling coupled with antibody array experiments using endostatin to probe the angiogenic signaling network in human endothelial cells were performed. The results reveal constraints on the measuring process that are of a similar kind as those implied by the uncertainty principle of quantum mechanics as described by Werner Heisenberg. We describe this analogy and argue for its heuristic utility in the conceptualization of angiogenesis as an important step in tumor formation.

  13. The Krichever map, vector bundles over algebraic curves, and Heisenberg algebras

    NASA Astrophysics Data System (ADS)

    Adams, M. R.; Bergvelt, M. J.

    1993-06-01

    We study the Grassmannian Gr {/x n } consisting of equivalence classes of rank n algebraic vector bundles over a Riemann surface X with an holomorphic trivialization at a fixed point p. Commutative subalgebras of gl(n, H λ), H λ being the ring of functions holomorphic on a punctured disc about p, define flows on the Grassmannian, giving rise to classes of solutions to multi-component KP hierarchies. These commutative subalgebras correspond to Heisenberg algebras in the Kac-Moody algebra associated to gl(n, H λ). One can obtain, by the Krichever map, points of Gr {/x n } (and solutions of mcKP) from coverings f: Y→X and other geometric data. Conversely for every point of Gr {/x n } and for every choice of Heisenberg algebra we construct, using the cotangent bundle of Gr {/x n }, an algebraic curve covering X and other data, thus inverting the Krichever map. We show the explicit relation between the choice of Heisenberg algebra and the geometry of the covering space.

  14. Proportionality of the interfacial Dzyaloshinskii-Moriya interaction and the Heisenberg exchange

    NASA Astrophysics Data System (ADS)

    Nembach, Hans; Shaw, Justin; Weiler, Mathias; Jué, Emilie; Silva, Tom

    The Dzyaloshinkii-Moriya interaction (DMI) gives rise to chiral magnetic ordering and a shift of spin-wave frequencies, depending on their propagation direction. We employed Brillouin-Light-Scattering spectroscopy to measure this nonreciprocal frequency shift, which allowed us to directly determine the magnitude of the DMI in a series of Ni80Fe20(t)/Pt thin film bilayers where the thickness t ranged from 1 to 13 nm. It has also been predicted by theory that the DMI is proportional to the Heisenberg exchange for bulk magnetic oxides and metallic spin-glasses. We tested this prediction for our metallic system by independently determining the Heisenberg exchange via fitting the Bloch T3/2-law to the temperature dependence of the magnetization obtained from SQUID magnetometry. We find that the Ni80Fe20 thickness dependence of the DMI and the Heisenberg exchange are identical, which is consistent with the notion that both effects share the same underlying physics. This result will lead us to a deeper understanding of the DMI and related spin-orbitronic effects.-/

  15. Dynamics of hot random quantum spin chains: from anyons to Heisenberg spins

    NASA Astrophysics Data System (ADS)

    Parameswaran, Siddharth; Potter, Andrew; Vasseur, Romain

    2015-03-01

    We argue that the dynamics of the random-bond Heisenberg spin chain are ergodic at infinite temperature, in contrast to the many-body localized behavior seen in its random-field counterpart. First, we show that excited-state real-space renormalization group (RSRG-X) techniques suffer from a fatal breakdown of perturbation theory due to the proliferation of large effective spins that grow without bound. We repair this problem by deforming the SU (2) symmetry of the Heisenberg chain to its `anyonic' version, SU(2)k , where the growth of effective spins is truncated at spin S = k / 2 . This enables us to construct a self-consistent RSRG-X scheme that is particularly simple at infinite temperature. Solving the flow equations, we compute the excited-state entanglement and show that it crosses over from volume-law to logarithmic scaling at a length scale ξk ~eαk3 . This reveals that (a) anyon chains have random-singlet-like excited states for any finite k; and (b) ergodicity is restored in the Heisenberg limit k --> ∞ . We acknowledge support from the Quantum Materials program of LBNL (RV), the Gordon and Betty Moore Foundation (ACP), and UC Irvine startup funds (SAP).

  16. Climate-based archetypes for the environmental fate assessment of chemicals.

    PubMed

    Ciuffo, Biagio; Sala, Serenella

    2013-11-15

    Emissions of chemicals have been on the rise for years, and their impacts are greatly influenced by spatial differentiation. Chemicals are usually emitted locally but their impact can be felt both locally and globally, due to their chemical properties and persistence. The variability of environmental parameters in the emission compartment may affect the chemicals' fate and the exposure at different orders of magnitude. The assessment of the environmental fate of chemicals and the inherent spatial differentiation requires the use of multimedia models at various levels of complexity (from a simple box model to complex computational and high-spatial-resolution models). The objective of these models is to support ecological and human health risk assessment, by reducing the uncertainty of chemical impact assessments. The parameterisation of spatially resolved multimedia models is usually based on scenarios of evaluative environments, or on geographical resolutions related to administrative boundaries (e.g. countries/continents) or landscape areas (e.g. watersheds, eco-regions). The choice of the most appropriate scale and scenario is important from a management perspective, as a balance should be reached between a simplified approach and computationally intensive multimedia models. In this paper, which aims to go beyond the more traditional approach based on scale/resolution (cell, country, and basin), we propose and assess climate-based archetypes for the impact assessment of chemicals released in air. We define the archetypes based on the main drivers of spatial variability, which we systematically identify by adopting global sensitivity analysis techniques. A case study that uses the high resolution multimedia model MAPPE (Multimedia Assessment of Pollutant Pathways in the Environment) is presented. Results of the analysis showed that suitable archetypes should be both climate- and chemical-specific, as different chemicals (or groups of them) have different traits

  17. Recommendation of standardized health learning contents using archetypes and semantic web technologies.

    PubMed

    Legaz-García, María del Carmen; Martínez-Costa, Catalina; Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás

    2012-01-01

    Linking Electronic Healthcare Records (EHR) content to educational materials has been considered a key international recommendation to enable clinical engagement and to promote patient safety. This would suggest citizens to access reliable information available on the web and to guide them properly. In this paper, we describe an approach in that direction, based on the use of dual model EHR standards and standardized educational contents. The recommendation method will be based on the semantic coverage of the learning content repository for a particular archetype, which will be calculated by applying semantic web technologies like ontologies and semantic annotations.

  18. Climate-based archetypes for the environmental fate assessment of chemicals.

    PubMed

    Ciuffo, Biagio; Sala, Serenella

    2013-11-15

    Emissions of chemicals have been on the rise for years, and their impacts are greatly influenced by spatial differentiation. Chemicals are usually emitted locally but their impact can be felt both locally and globally, due to their chemical properties and persistence. The variability of environmental parameters in the emission compartment may affect the chemicals' fate and the exposure at different orders of magnitude. The assessment of the environmental fate of chemicals and the inherent spatial differentiation requires the use of multimedia models at various levels of complexity (from a simple box model to complex computational and high-spatial-resolution models). The objective of these models is to support ecological and human health risk assessment, by reducing the uncertainty of chemical impact assessments. The parameterisation of spatially resolved multimedia models is usually based on scenarios of evaluative environments, or on geographical resolutions related to administrative boundaries (e.g. countries/continents) or landscape areas (e.g. watersheds, eco-regions). The choice of the most appropriate scale and scenario is important from a management perspective, as a balance should be reached between a simplified approach and computationally intensive multimedia models. In this paper, which aims to go beyond the more traditional approach based on scale/resolution (cell, country, and basin), we propose and assess climate-based archetypes for the impact assessment of chemicals released in air. We define the archetypes based on the main drivers of spatial variability, which we systematically identify by adopting global sensitivity analysis techniques. A case study that uses the high resolution multimedia model MAPPE (Multimedia Assessment of Pollutant Pathways in the Environment) is presented. Results of the analysis showed that suitable archetypes should be both climate- and chemical-specific, as different chemicals (or groups of them) have different traits

  19. Recommendation of standardized health learning contents using archetypes and semantic web technologies.

    PubMed

    Legaz-García, María del Carmen; Martínez-Costa, Catalina; Menárguez-Tortosa, Marcos; Fernández-Breis, Jesualdo Tomás

    2012-01-01

    Linking Electronic Healthcare Records (EHR) content to educational materials has been considered a key international recommendation to enable clinical engagement and to promote patient safety. This would suggest citizens to access reliable information available on the web and to guide them properly. In this paper, we describe an approach in that direction, based on the use of dual model EHR standards and standardized educational contents. The recommendation method will be based on the semantic coverage of the learning content repository for a particular archetype, which will be calculated by applying semantic web technologies like ontologies and semantic annotations. PMID:22874336

  20. A spin-liquid with pinch-line singularities on the pyrochlore lattice.

    PubMed

    Benton, Owen; Jaubert, L D C; Yan, Han; Shannon, Nic

    2016-01-01

    The mathematics of gauge theories lies behind many of the most profound advances in physics in the past 200 years, from Maxwell's theory of electromagnetism to Einstein's theory of general relativity. More recently it has become clear that gauge theories also emerge in condensed matter, a prime example being the spin-ice materials which host an emergent electromagnetic gauge field. In spin-ice, the underlying gauge structure is revealed by the presence of pinch-point singularities in neutron-scattering measurements. Here we report the discovery of a spin-liquid where the low-temperature physics is naturally described by the fluctuations of a tensor field with a continuous gauge freedom. This gauge structure underpins an unusual form of spin correlations, giving rise to pinch-line singularities: line-like analogues of the pinch points observed in spin-ice. Remarkably, these features may already have been observed in the pyrochlore material Tb2Ti2O7. PMID:27225400

  1. Supercooled spin liquid state in the frustrated pyrochlore Dy2Ti2O7

    PubMed Central

    Kassner, Ethan R.; Eyvazov, Azar B.; Pichler, Benjamin; Munsie, Timothy J. S.; Dabkowska, Hanna A.; Luke, Graeme M.; Davis, J. C. Séamus

    2015-01-01

    A “supercooled” liquid develops when a fluid does not crystallize upon cooling below its ordering temperature. Instead, the microscopic relaxation times diverge so rapidly that, upon further cooling, equilibration eventually becomes impossible and glass formation occurs. Classic supercooled liquids exhibit specific identifiers including microscopic relaxation times diverging on a Vogel–Tammann–Fulcher (VTF) trajectory, a Havriliak–Negami (HN) form for the dielectric function ε(ω,T), and a general Kohlrausch–Williams–Watts (KWW) form for time-domain relaxation. Recently, the pyrochlore Dy2Ti2O7 has become of interest because its frustrated magnetic interactions may, in theory, lead to highly exotic magnetic fluids. However, its true magnetic state at low temperatures has proven very difficult to identify unambiguously. Here, we introduce high-precision, boundary-free magnetization transport techniques based upon toroidal geometries and gain an improved understanding of the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7. We demonstrate a virtually universal HN form for the magnetic susceptibility χ(ω,T), a general KWW form for the real-time magnetic relaxation, and a divergence of the microscopic magnetic relaxation rates with the VTF trajectory. Low-temperature Dy2Ti2O7 therefore exhibits the characteristics of a supercooled magnetic liquid. One implication is that this translationally invariant lattice of strongly correlated spins may be evolving toward an unprecedented magnetic glass state, perhaps due to many-body localization of spin. PMID:26130810

  2. Quantum spin ices and magnetic states from dipolar-octupolar doublets on the pyrochlore lattice

    NASA Astrophysics Data System (ADS)

    Chen, Gang

    We consider a class of electron systems in which dipolar-octupolar Kramers doublets arise on the pyrochlore lattice. In the localized limit, the Kramers doublets are described by the effective spin 1/2 pseudospins. The most general nearest-neighbor exchange model between these pseudospins is the XYZ model. In additional to dipolar ordered and octupolar ordered magnetic states, we show that this XYZ model exhibits two distinct quantum spin ice (QSI) phases, that we dub dipolar QSI and octupolar QSI. These two QSIs are distinct symmetry enriched U(1) quantum spin liquids, enriched by the lattice symmetry. Moreover, the XYZ model is absent from the notorious sign problem for a quantum Monte Carlo simulation in a large parameter space. We discuss the potential relevance to real material systems such as Dy2Ti2O7, Nd2Zr2O7, Nd2Hf2O7, Nd2Ir2O7, Nd2Sn2O7 and Ce2Sn2O7. chggst@gmail.com, Refs: Y-P Huang, G Chen, M Hermele, Phys. Rev. Lett. 112, 167203 (2014).

  3. Quadrupole order in the frustrated pyrochlore magnet Tb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Takatsu, H.; Taniguchi, T.; Kittaka, S.; Sakakibara, T.; Kadowaki, H.

    2016-02-01

    We have studied the hidden long-range order (LRO) of the frustrated pyrochlore magnet Tb2Ti2O7 by means of specific-heat experiments and Monte-Carlo (MC) simulations, which has been discussed as the LRO of quadrupole moments inherent to the non-Kramers ion of Tb3+. We have found that the sharp specific-heat peak is collapsed into a broad hump by magnetic fields above 0.3 T for H//[001]. This result, qualitatively reproduced by MC simulations, suggests that a field-induced magnetic state overcomes the quadrupolar LRO state, as a similar case of a classical spin ice. The present results support the interpretation that Tb2+xTi2-xO7+y is a unique material in the boundary between the quadrupolar (x ⩾ xc = - 0.0025) and spin-liquid (x ⩽ xc) states, where the magnetic field along the [001] axis is a tuning parameter which induces the magnetic ordered state.

  4. Spin-liquid behavior and weak static magnetism in pyrochlore Pr2Ir2O7

    SciTech Connect

    Heffner, R H; Maclaughlin, D E; Nakatsuji, S; Machida, Y

    2008-01-01

    Muon spin relaxation experiments have been performed in powder samples of the pyrochlore iridate Pr{sub 2}Ir{sub 2}O{sub 7} for temperatures in the range 0.02-250 K. Two-component muon spin relaxation functions are observed up to {approx}> 150 K, indicating static magnetism with a freezing temperature T{sub f} of this value or higher. The static muon spin relaxation rate {Delta}. suggests weak-moment freezing ({approx} 10{sup -1} {micro}{sub B} at T = 0), probably due to Ir{sup 4+} spin ordering as in isostructural Y{sub 2}Ir{sub 2}O{sub 7}. The temperature dependence of {Delta} is highly unusual, decreasing smoothly by orders of magnitude but remaining nonzero for T < T{sub f}. The smoothness of {Delta}(T) suggests that Pr{sup 3+} moments do not order down to 0.025 K. The dynamic relaxation rate {Lambda} increases markedly below {approx}20 K, indicating a shift of spin fluctuation noise power to low frequencies in the spin-liquid state. At low temperatures {Lambda} is strong and temperature-independent, indicative of numerous low-lying spin excitations as is common in frustrated antiferromagnets.

  5. Evaluation of pulmonary function and respiratory symptoms in pyrochlore mine workers

    PubMed Central

    Borges, Ritta de Cássia Canedo Oliveira; Barros, José Cerqueira; Oliveira, Fabrício Borges; Brunherotti, Marisa Andrade; Quemelo, Paulo Roberto Veiga

    2016-01-01

    ABSTRACT Objective: To identify respiratory symptoms and evaluate lung function in mine workers. Methods: This was a cross-sectional observational study involving production sector workers of a pyrochlore mining company. The subjects completed the British Medical Research Council questionnaire, which is designed to evaluate respiratory symptoms, occupational exposure factors, and smoking status. In addition, they underwent pulmonary function tests with a portable spirometer. Results: The study involved 147 workers (all male). The mean age was 41.37 ± 8.71 years, and the mean duration of occupational exposure was 12.26 ± 7.09 years. We found that 33 (22.44%) of the workers had respiratory symptoms and that 26 (17.69%) showed abnormalities in the spirometry results. However, we found that the spirometry results did not correlate significantly with the presence of respiratory symptoms or with the duration of occupational exposure. Conclusions: The frequencies of respiratory symptoms and spirometric changes were low when compared with those reported in other studies involving occupational exposure to dust. No significant associations were observed between respiratory symptoms and spirometry results.

  6. Synthesis and radiation tolerance of Lu2-xCexTi2O7 pyrochlores

    NASA Astrophysics Data System (ADS)

    Xia, Y.; Liu, C. G.; Yang, D. Y.; Wen, J.; Liu, H.; Mu, P. C.; Li, Y. H.

    2016-11-01

    As a nonradioactive surrogate for Pu, Ce is selected to study the solubility and radiation tolerance in pyrochlore matrixes. In this paper, we synthesized a series of Lu2-xCexTi2O7 (x = 0-0.7) samples. X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy were used to study the structure of Lu2-xCexTi2O7 (x = 0-0.7) with different Ce3+ content x. The results show that the maximum solubility of Ce3+ in Lu2Ti2O7 is 32 mol%. In order to study the radiation tolerance of these compounds, 400 keV Ne2+ was used to perform the irradiation experiments. The grazing incident X-ray diffraction patterns revealed that the radiation tolerance of the Lu2-xCexTi2O7 decreases with increasing Ce-content. This correlation between radiation tolerance and Ce-content was interpreted in terms of the antisite defect formation energies of Lu2-xCexTi2O7 (x = 0, 0.5, 1) based on the density functional theory.

  7. Magnetocaloric effect in pyrochlore antiferromagnet Gd2 Ti2 O7

    NASA Astrophysics Data System (ADS)

    Sosin, S. S.; Prozorova, L. A.; Smirnov, A. I.; Golov, A. I.; Berkutov, I. B.; Petrenko, O. A.; Balakrishnan, G.; Zhitomirsky, M. E.

    2005-03-01

    An adiabatic demagnetization process is studied in Gd2Ti2O7 , a geometrically frustrated antiferromagnet on a pyrochlore lattice. In contrast to conventional paramagnetic salts, this compound can exhibit a temperature decrease by a factor of 10 in the temperature range below the Curie-Weiss constant. The most efficient cooling is observed in the field interval between 120 and 60kOe corresponding to a crossover between saturated and spin-liquid phases. This phenomenon indicates that a considerable part of the magnetic entropy survives in the strongly correlated state. According to the theoretical model, this entropy is associated with a macroscopic number of local modes remaining gapless until the saturation field. Monte Carlo simulations on a classical spin model demonstrate good agreement with the experiment. The cooling power of the process is experimentally estimated with a view to possible technical applications. The results for Gd2Ti2O7 are compared to those for Gd3Ga5O12 , a well-known material for low temperature magnetic refrigeration.

  8. A spin-liquid with pinch-line singularities on the pyrochlore lattice

    PubMed Central

    Benton, Owen; Jaubert, L.D.C.; Yan, Han; Shannon, Nic

    2016-01-01

    The mathematics of gauge theories lies behind many of the most profound advances in physics in the past 200 years, from Maxwell's theory of electromagnetism to Einstein's theory of general relativity. More recently it has become clear that gauge theories also emerge in condensed matter, a prime example being the spin-ice materials which host an emergent electromagnetic gauge field. In spin-ice, the underlying gauge structure is revealed by the presence of pinch-point singularities in neutron-scattering measurements. Here we report the discovery of a spin-liquid where the low-temperature physics is naturally described by the fluctuations of a tensor field with a continuous gauge freedom. This gauge structure underpins an unusual form of spin correlations, giving rise to pinch-line singularities: line-like analogues of the pinch points observed in spin-ice. Remarkably, these features may already have been observed in the pyrochlore material Tb2Ti2O7. PMID:27225400

  9. CHARACTERIZATION OF A CERIUM-RICH PYROCHLORE-BASED CERAMIC NUCLEAR WASTE FORM

    SciTech Connect

    Giere, Reto; Segvich, Susan; Buck, Edgar C.

    2003-02-11

    Titanate ceramics have been proposed as candidate materials for immobilizing excess weapons plutonium. This study focuses on the characterization of a titanate-based ceramic through X-ray diffraction (XRD), electron probe microanalysis and electron energy-loss spectroscopy (EELS). Three distinct phases have been identified, and their volume fraction was determined from element distribution maps using Scionimage-NIH Analysis software. This analysis revealed that the pyrochlore-group phase betafite (A2Ti2O7) forms the matrix of the ceramic and occupies 90.4% of the volume. Uniformly distributed in this matrix are perovskite (A2Ti2O6) and Hf-enriched rutile (TiO2), which account for 6.4 vol% and 3.1 vol%, respectively. The studied ceramic exhibits an extremely low porosity (0.3 vol%), which is characterized by small (< 6 m), rounded and isolated pores. In the studied ceramic, A-site cations are represented by Ca, rare earth elements, and Hf. The powder XRD pattern of the ceramic allowed refining the unit cell parameters for the cubic betafite, which is characterized by a cell edge of 10.132±0.003Å. The EELS data indicate that Ce is present as both Ce3+ and Ce4+ in betafite, whereas in perovskite, all Ce is trivalent.

  10. Quantum spin ice: a search for gapless quantum spin liquids in pyrochlore magnets.

    PubMed

    Gingras, M J P; McClarty, P A

    2014-05-01

    The spin ice materials, including Ho2Ti2O7 and Dy2Ti2O7, are rare-earth pyrochlore magnets which, at low temperatures, enter a constrained paramagnetic state with an emergent gauge freedom. Spin ices provide one of very few experimentally realized examples of fractionalization because their elementary excitations can be regarded as magnetic monopoles and, over some temperature range, spin ice materials are best described as liquids of these emergent charges. In the presence of quantum fluctuations, one can obtain, in principle, a quantum spin liquid descended from the classical spin ice state characterized by emergent photon-like excitations. Whereas in classical spin ices the excitations are akin to electrostatic charges with a mutual Coulomb interaction, in the quantum spin liquid these charges interact through a dynamic and emergent electromagnetic field. In this review, we describe the latest developments in the study of such a quantum spin ice, focusing on the spin liquid phenomenology and the kinds of materials where such a phase might be found.

  11. Supercooled spin liquid state in the frustrated pyrochlore Dy2Ti2O7.

    PubMed

    Kassner, Ethan R; Eyvazov, Azar B; Pichler, Benjamin; Munsie, Timothy J S; Dabkowska, Hanna A; Luke, Graeme M; Davis, J C Séamus

    2015-07-14

    A "supercooled" liquid develops when a fluid does not crystallize upon cooling below its ordering temperature. Instead, the microscopic relaxation times diverge so rapidly that, upon further cooling, equilibration eventually becomes impossible and glass formation occurs. Classic supercooled liquids exhibit specific identifiers including microscopic relaxation times diverging on a Vogel-Tammann-Fulcher (VTF) trajectory, a Havriliak-Negami (HN) form for the dielectric function ε(ω, T), and a general Kohlrausch-Williams-Watts (KWW) form for time-domain relaxation. Recently, the pyrochlore Dy2Ti2O7 has become of interest because its frustrated magnetic interactions may, in theory, lead to highly exotic magnetic fluids. However, its true magnetic state at low temperatures has proven very difficult to identify unambiguously. Here, we introduce high precision, boundary-free magnetization transport techniques based upon toroidal geometries and gain an improved understanding of the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7. We demonstrate a virtually universal HN form for the magnetic susceptibility χ (ω, T), a general KWW form for the realtime magnetic relaxation, and a divergence of the microscopic magnetic relaxation rates with the VTF trajectory. Low-temperature Dy2Ti2O7 therefore exhibits the characteristics of a supercooled magnetic liquid. One implication is that this translationally invariant lattice of strongly correlated spins may be evolving toward an unprecedented magnetic glass state, perhaps due to many-body localization of spin. PMID:26130810

  12. Ferroelectric studies of excessive Sm{sup 3+} containing perovskite PZT and pyrochlore biphase ceramics

    SciTech Connect

    Babu, T. Anil; Sastry, D. L.; Ramesh, K. V.; Reddy, V. Raghavendra

    2014-04-24

    Polycrystalline samples of Sm{sup 3+} modified Pb{sub 1−x} Sm{sub 2x/3} (Zr{sub 0.6}Ti{sub 0.4}) O{sub 3} (PSZT) ceramics (where x = 0.1, 0.2, 0.3, 0.4) have been prepared by a high energy ball milling technique, followed by calcination at 950°C and sintering at 1150°C. As x is increased more than 0.1 mole%, considerable secondary phase has been formed. This phase has been identified as pyrochlore Sm{sub 2}Ti{sub 2}O{sub 7} from its X-ray diffraction (XRD) peaks. The XRD studies also indicate that the perovskte phases of the present systems undergo a dopant induced phase transformation from rhombohedral to tetragonal strucure. All the samples exhibit diffuse but non-relaxor type ferroelectric phase transition. The results of dielectric and hysteresis studies of these materials are presented.

  13. Ultralow dielectric losses in pyrochlore films of the PbO-MgO-Nb{sub 2}O{sub 5}-TiO{sub 2} system

    SciTech Connect

    Zhu, X. H.; Defaye, E.; Suhm, A.; Fribourg-blanc, E.; Aied, M.

    2009-03-23

    (1-x)Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3} (PMNT) (with x=0.1) thin films were prepared on Pt-coated silicon substrates by radio-frequency magnetron sputtering and postdeposition annealing method. A well-crystallized pyrochlore phase structure, which started to nucleate and grow at 450-500 deg. C, was formed in the PMNT thin films. These pyrochlore-structured PMNT thin films show ultralow dielectric losses with a typical loss tangent as low as 0.001, accompanied by a relatively high dielectric constant ({epsilon}{sub r}=176). Such an extremely low dielectric loss, having never been obtained in thin films of perovskite PMNT, is probably ascribed to the specific structural feature of pyrochlore phase, chemically different from its perovskite counterpart, and ascribed to the avoidance of the polar domain-related losses.

  14. Restructuring an EHR system and the Medical Markup Language (MML) standard to improve interoperability by archetype technology.

    PubMed

    Kobayashi, Shinji; Kume, Naoto; Yoshihara, Hiroyuki

    2015-01-01

    In 2001, we developed an EHR system for regional healthcare information inter-exchange and to provide individual patient data to patients. This system was adopted in three regions in Japan. We also developed a Medical Markup Language (MML) standard for inter- and intra-hospital communications. The system was built on a legacy platform, however, and had not been appropriately maintained or updated to meet clinical requirements. To improve future maintenance costs, we reconstructed the EHR system using archetype technology on the Ruby on Rails platform, and generated MML equivalent forms from archetypes. The system was deployed as a cloud-based system for preliminary use as a regional EHR. The system now has the capability to catch up with new requirements, maintaining semantic interoperability with archetype technology. It is also more flexible than the legacy EHR system. PMID:26262183

  15. Restructuring an EHR system and the Medical Markup Language (MML) standard to improve interoperability by archetype technology.

    PubMed

    Kobayashi, Shinji; Kume, Naoto; Yoshihara, Hiroyuki

    2015-01-01

    In 2001, we developed an EHR system for regional healthcare information inter-exchange and to provide individual patient data to patients. This system was adopted in three regions in Japan. We also developed a Medical Markup Language (MML) standard for inter- and intra-hospital communications. The system was built on a legacy platform, however, and had not been appropriately maintained or updated to meet clinical requirements. To improve future maintenance costs, we reconstructed the EHR system using archetype technology on the Ruby on Rails platform, and generated MML equivalent forms from archetypes. The system was deployed as a cloud-based system for preliminary use as a regional EHR. The system now has the capability to catch up with new requirements, maintaining semantic interoperability with archetype technology. It is also more flexible than the legacy EHR system.

  16. Phase Stability and Pressure Dependence of Defect Formation in Gd2Ti2O7 and Gd2Zr2O7 Pyrochlores

    NASA Astrophysics Data System (ADS)

    Zhang, F. X.; Wang, J. W.; Lian, J.; Lang, M. K.; Becker, U.; Ewing, R. C.

    2008-02-01

    We report dramatically different behaviors between isostructural Gd2Ti2O7 and Gd2Zr2O7 pyrochlore at pressures up to 44 GPa, in which the substitution of Ti for Zr significantly increases structural stability. Upon release of pressure, the Gd2Ti2O7 becomes amorphous. In contrast, the high-pressure phase of Gd2Zr2O7 transforms to a disordered defect-fluorite structure. First-principle calculations for both compositions revealed that the response of pyrochlore to high pressure is controlled by the intrinsic energetics of defect formation.

  17. Phase stability and pressure dependence of defect formation in Gd2Ti2O7 and Gd2Zr2O7 pyrochlores.

    PubMed

    Zhang, F X; Wang, J W; Lian, J; Lang, M K; Becker, U; Ewing, R C

    2008-02-01

    We report dramatically different behaviors between isostructural Gd2Ti2O7 and Gd2Zr2O7 pyrochlore at pressures up to 44 GPa, in which the substitution of Ti for Zr significantly increases structural stability. Upon release of pressure, the Gd2Ti2O7 becomes amorphous. In contrast, the high-pressure phase of Gd2Zr2O7 transforms to a disordered defect-fluorite structure. First-principle calculations for both compositions revealed that the response of pyrochlore to high pressure is controlled by the intrinsic energetics of defect formation.

  18. A collective unconscious reconsidered: Jung's archetypal imagination in the light of contemporary psychology and social science.

    PubMed

    Hunt, Harry T

    2012-02-01

    A needed rapprochement between Jung and the contemporary human sciences may rest less on the much debated relevance of a biologistic collective unconscious than on a re-inscribing of an archetypal imagination, as the phenomenological and empirical core of Jungian psychology. The most promising approaches in this regard in terms of theory and research in psychology come from combining the cognitive psychology of metaphor and synaesthesia, individual differences in imaginative absorption and openness to numinous experience and spirituality as a form of symbolic intelligence. On the socio-cultural side, this cognitive psychology of archetypal imagination is also congruent with Lévi-Strauss on the metaphoric roots of mythological thinking, and Durkheim on a sociology of collective consciousness. This conjoined perspective, while validating the cross cultural commonality of physical metaphor intuited by Jung and Hillman on alchemy, also shows Jung's Red Book, considered as the expressive source for his more formal psychology, to be far closer in spirit to a socio-cultural collective consciousness, based on metaphoric imagination, than to a phylogenetic or evolutionary unconscious. A mutual re-inscribing of Jung into congruent areas of contemporary psychology, anthropology, sociology, and vice versa, can help to further validate Jung's key observations and is fully consistent with Jung's own early efforts at synthesis within the human sciences. PMID:22288542

  19. Water Resources System Archetypes: Towards a Holistic Understanding of Persistent Water Resources Problems

    NASA Astrophysics Data System (ADS)

    Mirchi, A.; Watkins, D. W.; Madani, K.

    2011-12-01

    Water resources modeling, a well-established tool in water resources planning and management practice, facilitates understanding of the physical and socio-economic processes impacting the wellbeing of humans and ecosystems. While watershed models continue to become more holistic, there is a need for appropriate frameworks and tools for integrated conceptualization of problems to provide reliable qualitative and quantitative bases for policy selection. In recent decades, water resources professionals have become increasingly cognizant of important feedback relationships within water resources systems. We contend that a systems thinking paradigm is required to facilitate characterization of the closed-loop nature of these feedbacks. Furthermore, a close look at different water resources issues reveals that, while many water resources problems are essentially very similar in nature, they continuously appear in different geographical locations. In the systems thinking literature, a number of generic system structures known as system archetypes have been identified to describe common patterns of problematic behavior within systems. In this research, we identify some main system archetypes governing water resources systems, demonstrating their benefits for holistic understanding of various classes of persistent water resources problems. Using the eutrophication problem of Lake Allegan, Michigan, as a case study, we illustrate how the diagnostic tools of system dynamics modeling can facilitate identification of problematic feedbacks within water resources systems and provide insights for sustainable development.

  20. Reconceptualizing successful aging among black women and the relevance of the strong black woman archetype.

    PubMed

    Baker, Tamara A; Buchanan, NiCole T; Mingo, Chivon A; Roker, Rosalyn; Brown, Candace S

    2015-02-01

    Although there are multiple pathways to successful aging, little is known of what it means to age successfully among black women. There is a growing body of literature suggesting that black women experience a number of social challenges (sexism and racism) that may present as barriers to aging successfully. Applying aspects of the Strong Black Women ideal, into theoretical concepts of successful aging, may be particularly relevant in understanding which factors impair or promote the ability of black women to age successfully. The Strong Black Women archetype is a culturally salient ideal prescribing that black women render a guise of self-reliance, selflessness, and psychological, emotional, and physical strength. Although this ideal has received considerable attention in the behavioral sciences, it has been largely absent within the gerontology field. Nevertheless, understanding the dynamics of this cultural ideal may enhance our knowledge while developing an appreciation of the black woman's ability to age successfully. Rather than summarize the social, physical, and mental health literature focusing on health outcomes of black women, this conceptual review examines the Strong Black Women archetype and its application to the lived experiences of black women and contributions to current theories of successful aging. Focusing on successful aging exclusively among black women enhances our understanding of this group by considering their identity as women of color while recognizing factors that dictate their ability to age successfully.