Magnetic properties of a ferromagnet spin-S, Ising, XY and Heisenberg models semi-infinites systems
International Nuclear Information System (INIS)
Masrour, R.; Hamedoun, M.; Hourmatallah, A.; Bouslykhane, K.; Benzakour, N.
2008-01-01
The magnetic properties of a ferromagnet spin-S a disordered semi-infinite system with a face-centered cubic lattice are investigated using the high-temperature series expansions technique extrapolated with Pade approximants method for Heisenberg, XY and Ising models. The reduced critical temperature of the system τ c =(k B T c )/(2S(S+1)J b ) is studied as function of the thickness of the film and the exchange interactions in the bulk, and within the surfaces J b ,J s and J perpendicular , respectively. It is found that τ c increases with the exchange interactions of surface. The magnetic phase diagrams (τ c versus the dilution x) and the percolation threshold are obtained
Phase transition in Ising, XY and Heisenberg magnetic films
Energy Technology Data Exchange (ETDEWEB)
Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Route Sidi Bouzid - BP 63 46000 Safi (Morocco); LMPHE, Faculte des Sciences, Universite Mohamed V, Rabat (Morocco); Hamedoun, M. [Institute for Nanomaterials and Nanotechnologies, Rabat (Morocco); Academie Hassan II des Sciences et Techniques, Rabat (Morocco); Benyoussef, A. [LMPHE, Faculte des Sciences, Universite Mohamed V, Rabat (Morocco); Institute for Nanomaterials and Nanotechnologies, Rabat (Morocco); Academie Hassan II des Sciences et Techniques, Rabat (Morocco)
2012-01-01
The phase transition and magnetic properties of a ferromagnet spin-S, a disordered diluted thin and semi-infinite film with a face-centered cubic lattice are investigated using the high-temperature series expansions technique extrapolated with Pade approximants method for Heisenberg, XY and Ising models. The reduced critical temperature of the system {tau}{sub c} is studied as function of the thickness of the thin film and the exchange interactions in the bulk, and within the surfaces J{sub b}, J{sub s} and J{sub Up-Tack }, respectively. It is found that {tau}{sub c} increases with the exchange interactions of surface. The magnetic phase diagrams ({tau}{sub c} versus the dilution x) and the percolation threshold are obtained. The shifts of the critical temperatures T{sub c}(l) from the bulk value (T{sub c}({infinity})/T{sub c}(l) - 1) can be described by a power law l{sup -{lambda}}, where {lambda} = 1/{upsilon} is the inverse of the correlation length exponent.
Influence of Non-Uniform Magnetic Field on Quantum Teleportation in Heisenberg XY Model
Institute of Scientific and Technical Information of China (English)
SHAO Bin; YANG Tie-jian; ZHAO Yue-hong; ZOU Jian
2007-01-01
By considering the intrinsic decoherence, the validity of quantum teleportation of a two-qubit 1D Heisenberg XY chain in a non-uniform external magnetic field is studied. The fidelity as the measurement of a possible quantum teleportation is calculated and the effects of the non-uniform magnetic field and the intrinsic decoherence are discussed. It is found that anti-parallel magnetic field is more favorable for teleportation and the fidelity is suppressed by the intrinsic decoherence.
Quantum teleportation via a two-qubit Heisenberg XY chain-effects of anisotropy and magnetic field
Energy Technology Data Exchange (ETDEWEB)
Yeo Ye [Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WB (United Kingdom); Liu Tongqi [Department of Engineering, Trumpington Street, Cambridge CB3 1PZ (United Kingdom); Lu Yuen [Computer Laboratory, William Gates Building, 15 J J Thomson Avenue, Cambridge CB3 0FD (United Kingdom); Yang Qizhong [Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE (United Kingdom)
2005-04-08
In this paper we study the influence of anisotropy on the usefulness of the entanglement in a two-qubit Heisenberg XY chain at thermal equilibrium in the presence of an external magnetic field, as a resource for quantum teleportation via the standard teleportation protocol. We show that the nonzero thermal entanglement produced by adjusting the external magnetic field beyond some critical strength is a useful resource. We also consider entanglement teleportation via two two-qubit Heisenberg XY chains.
Quantum teleportation via a two-qubit Heisenberg XY chain-effects of anisotropy and magnetic field
International Nuclear Information System (INIS)
Yeo Ye; Liu Tongqi; Lu Yuen; Yang Qizhong
2005-01-01
In this paper we study the influence of anisotropy on the usefulness of the entanglement in a two-qubit Heisenberg XY chain at thermal equilibrium in the presence of an external magnetic field, as a resource for quantum teleportation via the standard teleportation protocol. We show that the nonzero thermal entanglement produced by adjusting the external magnetic field beyond some critical strength is a useful resource. We also consider entanglement teleportation via two two-qubit Heisenberg XY chains
de Sousa, J. Ricardo; de Albuquerque, Douglas F.
1997-02-01
By using two approaches of renormalization group (RG), mean field RG (MFRG) and effective field RG (EFRG), we study the critical properties of the simple cubic lattice classical XY and classical Heisenberg models. The methods are illustrated by employing its simplest approximation version in which small clusters with one ( N‧ = 1) and two ( N = 2) spins are used. The thermal and magnetic critical exponents, Yt and Yh, and the critical parameter Kc are numerically obtained and are compared with more accurate methods (Monte Carlo, series expansion and ε-expansion). The results presented in this work are in excellent agreement with these sophisticated methods. We have also shown that the exponent Yh does not depend on the symmetry n of the Hamiltonian, hence the criteria of universality for this exponent is only a function of the dimension d.
The chirality operators for Heisenberg spin systems
International Nuclear Information System (INIS)
Subrahmanyam, V.
1994-01-01
The ground state of closed Heisenberg spin chains with an odd number of sites has a chiral degeneracy, in addition to a two-fold Kramers degeneracy. A non-zero 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. (author). 3 refs
Spin-chirality decoupling in Heisenberg spin glasses and related systems
Kawamura, Hikaru
2006-01-01
Recent studies on the spin and the chirality orderings of the three-dimensional Heisenberg spin glass and related systems are reviewed with particular emphasis on the possible spin-chirality decoupling phenomena. Chirality scenario of real spin-glass transition and its experimental consequence on the ordering of Heisenberg-like spin glasses are discussed.
Werner Heisenberg; Werner Heisenberg
Energy Technology Data Exchange (ETDEWEB)
Schiemann, G.
2008-07-01
This book contains a biography of Heisenberg, a description of the development of quantum mechanics, a consideration of connections of philosophy and physics, and a description of the scientific picture of the world. Finally a list of books written by Heisenberg respectively connected with his work is presented. (HSI)
Chiral-glass transition in a diluted dipolar-interaction Heisenberg system
International Nuclear Information System (INIS)
Zhang Kaicheng; Liu Guibin; Zhu Yan
2011-01-01
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. - Highlights: → We define the chirality in a diluted dipolar Heisenberg system. → The system undergoes a chiral-glass transition at finite temperature. → We extract the critical exponents of the chiral-glass transition.
A mean field study of the quasi-one-dimensional antiferromagnetic anisotropic Heisenberg model
International Nuclear Information System (INIS)
Benyoussef, A.
1996-10-01
The effect of the chain and the dimer anisotropies on the ground state energy and the energy gap of the spin-1/2 quasi-one-dimensional antiferromagnetic Heisenberg model is investigated using a mean field theory. The dependence of the magnetization and the effective hopping parameters on the anisotropy α xy (=J xy perpendicular /J xy parallel ) are presented for several values of the chain anisotropy. However, such a system exhibits a transition from antiferromagnetic ordered to disordered phases for arbitrary chain anisotropy and dimer anisotropy. (author). 22 refs, 11 figs
XX/XY system of sex determination in the geophilomorph centipede Strigamia maritima
Czech Academy of Sciences Publication Activity Database
Green, J. E.; Dalíková, Martina; Sahara, K.; Marec, František; Akam, M.
2016-01-01
Roč. 11, č. 2 (2016), č. článku e0150292. E-ISSN 1932-6203 R&D Projects: GA AV ČR IAA600960925; GA ČR(CZ) GA14-22765S Institutional support: RVO:60077344 Keywords : sex determination * Strigamia maritima * XX/XY system Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.806, year: 2016 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0150292
Lorentz-force equations as Heisenberg equations for a quantum system in the euclidean space
International Nuclear Information System (INIS)
Rodriguez D, R.
2007-01-01
In an earlier work, the dynamic equations for a relativistic charged particle under the action of electromagnetic fields were formulated by R. Yamaleev in terms of external, as well as internal momenta. Evolution equations for external momenta, the Lorentz-force equations, were derived from the evolution equations for internal momenta. The mapping between the observables of external and internal momenta are related by Viete formulae for a quadratic polynomial, the characteristic polynomial of the relativistic dynamics. In this paper we show that the system of dynamic equations, can be cast into the Heisenberg scheme for a four-dimensional quantum system. Within this scheme the equations in terms of internal momenta play the role of evolution equations for a state vector, whereas the external momenta obey the Heisenberg equation for an operator evolution. The solutions of the Lorentz-force equation for the motion inside constant electromagnetic fields are presented via pentagonometric functions. (Author)
XX/XY System of Sex Determination in the Geophilomorph Centipede Strigamia maritima.
Directory of Open Access Journals (Sweden)
Jack E Green
Full Text Available We show that the geophilomorph centipede Strigamia maritima possesses an XX/XY system of sex chromosomes, with males being the heterogametic sex. This is, to our knowledge, the first report of sex chromosomes in any geophilomorph centipede. Using the recently assembled Strigamia genome sequence, we identified a set of scaffolds differentially represented in male and female DNA sequence. Using quantitative real-time PCR, we confirmed that three candidate X chromosome-derived scaffolds are present at approximately twice the copy number in females as in males. Furthermore, we confirmed that six candidate Y chromosome-derived scaffolds contain male-specific sequences. Finally, using this molecular information, we designed an X chromosome-specific DNA probe and performed fluorescent in situ hybridization against mitotic and meiotic chromosome spreads to identify the Strigamia XY sex-chromosome pair cytologically. We found that the X and Y chromosomes are recognizably different in size during the early pachytene stage of meiosis, and exhibit incomplete and delayed pairing.
Magnon damping in two-dimensional Heisenberg ferromagnetic system
International Nuclear Information System (INIS)
Cheng, T.-M.; Li Lin; Ze Xianyu
2006-01-01
A magnon-phonon interaction model is set up for a two-dimensional insulating ferromagnetic system. By using Matsubara function theory we have studied the magnon damping -I m Σ* (1) (k->) and calculated the magnon damping -I m Σ* (1) (k->) curve on the main symmetric point and line in the Brillouin zone for various parameters in the system. It is concluded that at the boundary of Brillouin zone there is a strong magnon damping. However, the magnon damping is very weak on the zone of small wave vector and the magnon damping reaches maximal value at very low temperature. The contributions of longitudinal phonon and transverse phonon on the magnon damping are compared and the influences of various parameters are also discussed
System simulation application for determining the size of daily raw material purchases at PT XY
Napitupulu, H. L.
2018-02-01
Every manufacturing company needs to implement green production, including PT XY as a marine catchment processing industry in Sumatera Utara Province. The company is engaged in the processing of squid for export purposes. The company’s problem relates to the absence of a decision on the daily purchase amount of the squid. The purchase of daily raw materials in varying quantities has caused companies to face the problem of excess raw materials or otherwise the lack of raw materials. The low purchase of raw materials will result in reduced productivity, while large purchases will lead to increased cooling costs for storage of excess raw materials, as well as possible loss of damage raw material. Therefore it is necessary to determine the optimal amount of raw material purchases every day. This can be determined by applying simulation. Application of system simulations can provide the expected optimal amount of raw material purchases.
Abhinav, Kumar; Guha, Partha
2018-03-01
Through the Hasimoto map, various dynamical systems can be mapped to different integrodifferential generalizations of Nonlinear Schrödinger (NLS) family of equations some of which are known to be integrable. Two such continuum limits, corresponding to the inhomogeneous XXX Heisenberg spin chain [J. Phys. C 15, L1305 (1982)] and that of a thin vortex filament moving in a superfluid with drag [Eur. Phys. J. B 86, 275 (2013) 86; Phys. Rev. E 91, 053201 (2015)], are shown to be particular non-holonomic deformations (NHDs) of the standard NLS system involving generalized parameterizations. Crucially, such NHDs of the NLS system are restricted to specific spectral orders that exactly complements NHDs of the original physical systems. The specific non-holonomic constraints associated with these integrodifferential generalizations additionally posses distinct semi-classical signature.
DEFF Research Database (Denmark)
Bhaskar, Mahajan Sagar; Sanjeevikumar, Padmanaban; Wheeler, Patrick
2016-01-01
A New breed of a buck boost converter, named as the XY converter family is proposed in this article. In the XY family, 16 topologies are presented which are highly suitable for renewable energy applications which require a high ratio of DC-DC converter; such as a photovoltaic multilevel inverter...... system, high voltage automotive applications and industrial drives. Compared to the traditional boost converter and existing recent converters, the proposed XY converter family has the ability to provide a higher output voltage by using less number of power devices and reactive components. Other distinct...... features of the XY converter family are i) Single control switch ii) Provide negative output voltage iii) Non-isolated topologies iv) High conversion ratio without making the use of high duty cycle and v) modular structure. XY family is compared with the recent high step-up converters and the detailed...
International Nuclear Information System (INIS)
Fridman, Yu.A.; Matunin, D.A.; Klevets, Ph.N.; Kosmachev, O.A.
2009-01-01
The phase states of the 2D non-Heisenberg ferromagnetic with anisotropic bilinear and biquadratic exchange interactions are investigated. The limiting cases of the system under consideration are the two-dimensional XY-model with biquadratic exchange interaction and the isotropic Heisenberg ferromagnetic. The account of the magnetic dipole interaction leads to the realization of spatially inhomogeneous quadrupolar phase. The stability regions of various phase transitions for different values of the material parameters are studied. The phase diagram is built. Besides, the temperature phase transitions are investigated. The influence of the magnetoelastic interaction on the formation of the long-range quadrupolar order is determined.
3-D quantum Heisenberg ferromagnet with random anisotropy
International Nuclear Information System (INIS)
Santos, R.M.Z. dos; Santos, Raimundo R. dos; Mariz, A.M.; Rio Grande do Norte Univ., Natal; Tsallis, C.
1985-01-01
Critical properties of the 3-D quantum Heisenberg ferromagnet with random anisotropies; that is, the coupling between any pair of nearest-neighbouring spins can be either isotropic (Heisenberg) or anisotropic (Ising-or XY-like) at random are studied. Within a Migdal-Kadanoff approximation the full critical frontier and correlation length critical exponents are obtained. It is found that the isotropic Heisenberg model is unstable (in the context of universality classes) in the presence of a small concentration of couplings with lower symmetry. (Author) [pt
Nocera, A.; Patel, N. D.; Fernandez-Baca, J.; Dagotto, E.; Alvarez, G.
2016-11-01
We study the effects of charge degrees of freedom on the spin excitation dynamics in quasi-one-dimensional magnetic materials. Using the density matrix renormalization group method, we calculate the dynamical spin structure factor of the Hubbard model at half electronic filling on a chain and on a ladder geometry, and compare the results with those obtained using the Heisenberg model, where charge degrees of freedom are considered frozen. For both chains and two-leg ladders, we find that the Hubbard model spectrum qualitatively resembles the Heisenberg spectrum—with low-energy peaks resembling spinonic excitations—already at intermediate on-site repulsion as small as U /t ˜2 -3 , although ratios of peak intensities at different momenta continue evolving with increasing U /t converging only slowly to the Heisenberg limit. We discuss the implications of these results for neutron scattering experiments and we propose criteria to establish the values of U /t of quasi-one-dimensional systems described by one-orbital Hubbard models from experimental information.
Critical behavior in a random field classical Heisenberg model for amorphous systems
International Nuclear Information System (INIS)
Albuquerque, Douglas F. de; Alves, Sandro Roberto L.; Arruda, Alberto S. de
2005-01-01
By using the differential operator technique and the effective field theory scheme, the critical behavior of amorphous classical Heisenberg ferromagnet of spin-1/2 in a random field is studied. The phase diagram in the T-H and T-α planes on a simple cubic lattice for a cluster with two spins is obtained. Tricritical points, reentrant phenomena and influence of the random field and amorphization on the transition temperature are discussed
Quantum discord for a central two-qubit system coupled to an XY-spin-chain environment
International Nuclear Information System (INIS)
Liu Benqiong; Shao Bin; Zou Jian
2010-01-01
We investigate the dynamic behaviors of quantum discord for a central two-qubit system coupled to an XY-spin-chain environment. In the weak-coupling regime, we show that the quantum discord for the two central qubits can become minimized rapidly close to the critical point of a quantum phase transition. By considering the two qubits that are initially prepared in the Werner state, we study the evolution of the quantum discord and that of entanglement under the same conditions. Our results imply that entanglement can disappear completely after a finite time, while the quantum discord decreases and tends to be a stable value according to the initial-state parameter for a very-long-time interval. In this sense, the quantum discord is more robust than entanglement for the quantum system exposed to the environment. The relation between the quantum correlations and the classical correlation is also shown for two particular cases.
Polynomial Heisenberg algebras
International Nuclear Information System (INIS)
Carballo, Juan M; C, David J Fernandez; Negro, Javier; Nieto, Luis M
2004-01-01
Polynomial deformations of the Heisenberg algebra are studied in detail. Some of their natural realizations are given by the higher order susy partners (and not only by those of first order, as is already known) of the harmonic oscillator for even-order polynomials. Here, it is shown that the susy partners of the radial oscillator play a similar role when the order of the polynomial is odd. Moreover, it will be proved that the general systems ruled by such kinds of algebras, in the quadratic and cubic cases, involve Painleve transcendents of types IV and V, respectively
Directory of Open Access Journals (Sweden)
Mikhail G Divashuk
Full Text Available Hemp (Cannabis sativa L. was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71, 5S rDNA (pCT4.2, a subtelomeric repeat (CS-1 and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants. The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.
Divashuk, Mikhail G; Alexandrov, Oleg S; Razumova, Olga V; Kirov, Ilya V; Karlov, Gennady I
2014-01-01
Hemp (Cannabis sativa L.) was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71), 5S rDNA (pCT4.2), a subtelomeric repeat (CS-1) and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants). The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.
On the completeness of the set of Bethe-Hulthen solutions of the linear Heisenberg system
International Nuclear Information System (INIS)
Caspers, W J; Labuz, M; Wal, A
2006-01-01
In this work we formulate the standard form of the solutions of the Heisenberg chain with periodic boundary conditions and show that these solutions can be transformed into the well-known Bethe-Hulthen solutions. The standard form is found by solving the secular problem, separated according to the irreducible representations of the translation group. The relevant parameters exp(ik j ) of the Bethe-Hulthen solutions are found from a set of linear equations with coefficients derived from the standard solutions. This correspondence between standard and Bethe-Hulthen solutions realizes the completeness of the Bethe-Hulthen method
Berry phase in Heisenberg representation
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.
Directory of Open Access Journals (Sweden)
Mohammed Daoud
2018-04-01
Full Text Available A relation is established in the present paper between Dicke states in a d-dimensional space and vectors in the representation space of a generalized Weyl–Heisenberg algebra of finite dimension d. This provides a natural way to deal with the separable and entangled states of a system of N = d − 1 symmetric qubit states. Using the decomposition property of Dicke states, it is shown that the separable states coincide with the Perelomov coherent states associated with the generalized Weyl–Heisenberg algebra considered in this paper. In the so-called Majorana scheme, the qudit (d-level states are represented by N points on the Bloch sphere; roughly speaking, it can be said that a qudit (in a d-dimensional space is describable by a N-qubit vector (in a N-dimensional space. In such a scheme, the permanent of the matrix describing the overlap between the N qubits makes it possible to measure the entanglement between the N qubits forming the qudit. This is confirmed by a Fubini–Study metric analysis. A new parameter, proportional to the permanent and called perma-concurrence, is introduced for characterizing the entanglement of a symmetric qudit arising from N qubits. For d = 3 ( ⇔ N = 2 , this parameter constitutes an alternative to the concurrence for two qubits. Other examples are given for d = 4 and 5. A connection between Majorana stars and zeros of a Bargmmann function for qudits closes this article.
X-ray excited optical luminescence studies on the system BaXY (X ...
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 65; Issue 2. X-ray excited optical luminescence studies on the system Ba (, =F, Cl, Br, I) ... India; Department of Chemical Engineering, National Taiwan University, Republic of China ... Proceedings of the International Workshop/Conference on Computational ...
Remark on Heisenberg's principle
International Nuclear Information System (INIS)
Noguez, G.
1988-01-01
Application of Heisenberg's principle to inertial frame transformations allows a distinction between three commutative groups of reciprocal transformations along one direction: Galilean transformations, dual transformations, and Lorentz transformations. These are three conjugate groups and for a given direction, the related commutators are all proportional to one single conjugation transformation which compensates for uniform and rectilinear motions. The three transformation groups correspond to three complementary ways of measuring space-time as a whole. Heisenberg's Principle then gets another explanation [fr
Exact gate sequences for universal quantum computation using the XY interaction alone
International Nuclear Information System (INIS)
Kempe, J.; Whaley, K.B.
2002-01-01
In a previous publication [J. Kempe et al., Quantum Computation and Information (Rinton Press, Princeton, NJ, 2001), Vol. 1, special issue, p. 33] we showed that it is possible to implement universal quantum computation with the anisotropic XY-Heisenberg exchange acting as a single interaction. To achieve this we used encodings of the states of the computation into a larger Hilbert space. This proof is nonconstructive, however, and did not explicitly give the trade-offs in time that are required to implement encoded single-qubit operations and encoded two-qubit gates. Here we explicitly give the gate sequences needed to simulate these operations on encoded qubits and qutrits (three-level systems) and analyze the trade-offs involved. We also propose a possible layout for the qubits in a triangular arrangement
Heisenberg spin glass experiments and the chiral ordering scenario
International Nuclear Information System (INIS)
Campbell, Ian A.; Petit, Dorothee C.M.C.
2010-01-01
An overview is given of experimental data on Heisenberg spin glass materials so as to make detailed comparisons with numerical results on model Heisenberg spin glasses, with particular reference to the chiral driven ordering transition scenario due to Kawamura and collaborators. On weak anisotropy systems, experiments show critical exponents which are very similar to those estimated numerically for the model Heisenberg chiral ordering transition but which are quite different from those at Ising spin glass transitions. Again on weak anisotropy Heisenberg spin glasses, experimental torque data show well defined in-field transverse ordering transitions up to strong applied fields, in contrast to Ising spin glasses where fields destroy ordering. When samples with stronger anisotropies are studied, critical and in-field behavior tend progressively towards the Ising limit. It can be concluded that the essential physics of laboratory Heisenberg spin glasses mirrors that of model Heisenberg spin glasses, where chiral ordering has been demonstrated numerically. (author)
Indian Academy of Sciences (India)
how Heisenberg identified the quantum mechan- ical exchange ... condensed matter physics from the Indian ... electrons per atom and 'm,' is the electronic mass. Dia- magnetism is .... what is the origin of this ordering field Hint = aM, that gives rise to a ... the case with magnetism, where the fundamental Inech- anism for the ...
Magnetic properties of a classical XY spin dimer in a “planar” magnetic field
Energy Technology Data Exchange (ETDEWEB)
Ciftja, Orion, E-mail: ogciftja@pvamu.edu [Department of Physics, Prairie View A& M University, Prairie View, TX 77446 (United States); Prenga, Dode [Department of Physics, Faculty of Natural Sciences, University of Tirana, Bul. Zog I, Tirana (Albania)
2016-10-15
Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a “planar” external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin–spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks. - Highlights: • Exact magnetic properties of a dimer system of classical XY spins in magnetic field. • Partition function in nonzero magnetic field obtained in closed-form. • Novel exact analytic results are important for spin models in a magnetic field. • Result provides benchmarks to gauge the accuracy of computational techniques.
Nuclear relaxation study of the spin dynamics in a one-dimensional Heisenberg system, TMMC
International Nuclear Information System (INIS)
Bakheit, M.A.
1974-01-01
Changes in the nuclear relaxation time as a function of the magnetic field intensity in TMMC are very different wether the field direction is parallel or perpendicular to the direction of the exchange chains (vector c). In parallel field, the relaxation probability increases as the field decreases. The process of spin diffusion in a one-dimensional system is well illustrated by the changes experimentally observed. In perpendicular field, the relaxation probability is constant as far as H 0 >2kG, it clearly decreases for H 0 [fr
Theory of a many boson system with the deformed Heisenberg algebra
Directory of Open Access Journals (Sweden)
I.O. Vakarchuk
2015-09-01
Full Text Available We propose to consider nonlinear fluctuations in the theory of liquid 4He deforming the commutation relations between the generalized coordinates and momenta. The generalized coordinates are the coefficients of the density fluctuations of the Bose particles. The deformation parameter takes into account effects of three- and four-particle correlations in the behavior of the system. This parameter is defined from the experimental values of the elementary excitation spectrum and the structure factor extrapolated to T=0 K. The numerical estimation of the ground state energy and the Bose condensate fraction is made. The elementary excitation spectrum and the potential of interaction between the helium atoms are recovered.
Kim, Ki-Hyun; Choi, Young-Man; Gweon, Dae-Gab; Hong, Dong-Pyo; Kim, Koung-Suk; Lee, Suk-Won; Lee, Moon-Gu
2005-12-01
A decoupled dual servo (DDS) stage for ultra-precision scanning system is introduced in this paper. The proposed DDS consists of a 3 axis fine stage for handling and carrying workpieces and a XY coarse stage. Especially, the DDS uses three voice coil motors (VCM) as a planar actuation system of the fine stage to reduce the disturbances due to any mechanical connections with its coarse stage. VCMs are governed by Lorentz law. According to the law and its structure, there are no mechanical connections between coils and magnetic circuits. Moreover, the VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about 5mm2. To break that hurdle, the coarse stage with linear motors is used for the fine stage to move about 200mm2. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. Using MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. For linear motors, Halbach magnet linear motor is proposed and optimally designed in this paper. In addition, for their smooth movements without any frictions, guide systems of the DDS are composed of air bearings. And then, precisely to get their positions, linear scales with 0.1um resolution are used for the coarse's XY motions and plane mirror laser interferometers with 20nm for the fine's XYθz. On scanning, the two stages have same trajectories and are controlled. The control algorithm is Parallel method. The embodied ultra-precision scanning system has about 100nm tracking error and in-positioning stability.
Diamond lattice Heisenberg antiferromagnet
Oitmaa, J.
2018-04-01
We investigate ground-state and high-temperature properties of the nearest-neighbour Heisenberg antiferromagnet on the three-dimensional diamond lattice, using series expansion methods. The ground-state energy and magnetization, as well as the magnon spectrum, are calculated and found to be in good agreement with first-order spin-wave theory, with a quantum renormalization factor of about 1.13. High-temperature series are derived for the free energy, and physical and staggered susceptibilities for spin S = 1/2, 1 and 3/2, and analysed to obtain the corresponding Curie and Néel temperatures.
Energy Technology Data Exchange (ETDEWEB)
Hu, Ai-Yuan, E-mail: huaiyuanhuyuanai@126.com [School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331 (China); Zhang, A.-Jie [Military Operational Research Teaching Division of the 4th Department, PLA Academy of National Defense Information, Wuhan 430000 (China)
2016-02-01
The magnetic properties of a mixed spin-1/2 and spin-1 Heisenberg ferrimagnetic system on a two-dimensional square lattice are investigated by means of the double-time Green's function technique within the random phase decoupling approximation. The role of the nearest-, next-nearest-neighbors interactions and the exchange anisotropy in the Hamiltonian is explored. And their effects on the critical and compensation temperature are discussed in detail. Our investigation indicates that both the next-nearest-neighbor interactions and the anisotropy have a great effect on the phase diagram. - Highlights: • Spin-1/2 and spin-1 ferrimagnetic model is examined. • Green's function technique is used. • The role of the nearest-, next-nearest-neighbors interactions and the exchange anisotropy in the Hamiltonian is explored. • The next-nearest-neighbor interactions and the anisotropy have a great effect on the phase diagram.
Controllable entanglement sudden birth of Heisenberg spins
International Nuclear Information System (INIS)
Zheng Qiang; Zhi Qijun; Zhang Xiaoping; Ren Zhongzhou
2011-01-01
We investigate the Entanglement Sudden Birth (ESB) of two Heisenberg spins A and B. The third controller, qutrit C is introduced, which only has the Dzyaloshinskii-Moriya (DM) spin-orbit interaction with qubit B. We find that the DM interaction is necessary to induce the Entanglement Sudden Birth of the system qubits A and B, and the initial states of the system qubits and the qutrit C are also important to control its Entanglement Sudden Birth. (authors)
Impurity modes in the one-dimensional XXZ Heisenberg model
International Nuclear Information System (INIS)
Sousa, J.M.; Leite, R.V.; Landim, R.R.; Costa Filho, R.N.
2014-01-01
A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken.
First-Order Polynomial Heisenberg Algebras and Coherent States
International Nuclear Information System (INIS)
Castillo-Celeita, M; Fernández C, D J
2016-01-01
The polynomial Heisenberg algebras (PHA) are deformations of the Heisenberg- Weyl algebra characterizing the underlying symmetry of the supersymmetric partners of the Harmonic oscillator. When looking for the simplest system ruled by PHA, however, we end up with the harmonic oscillator. In this paper we are going to realize the first-order PHA through the harmonic oscillator. The associated coherent states will be also constructed, which turn out to be the well known even and odd coherent states. (paper)
Directory of Open Access Journals (Sweden)
Ynduráin, Francisco J.
2002-01-01
Full Text Available Not available
Los azares de las onomásticas hacen coincidir en este año el centenario del nacimiento de tres de los más grandes físicos del siglo XX. Dos de ellos, Fermi y Heisenberg, dejaron una marca fundamental en la ciencia (ambos, pero sobre todo el segundo y, el primero, también en la tecnología. Lawrence, indudablemente de un nivel inferior al de los otros dos, estuvo sin embargo en el origen de uno de los desarrollos tecnológicos que han sido básicos para la exploración del universo subnuclear en la segunda mitad del siglo que ha terminado hace poco, el de los aceleradores de partículas.
Quantum influence in the criticality of the spin- {1}/{2} anisotropic Heisenberg model
Ricardo de Sousa, J.; Araújo, Ijanílio G.
1999-07-01
We study the spin- {1}/{2} anisotropic Heisenberg antiferromagnetic model using the effective field renormalization group (EFRG) approach. The EFRG method is illustrated by employing approximations in which clusters with one ( N'=1) and two ( N=2) spins are used. The dependence of the critical temperature Tc (ferromagnetic-F case) and TN (antiferromagnetic-AF case) and thermal critical exponent, Yt, are obtained as a function of anisotropy parameter ( Δ) on a simple cubic lattice. We find that, in our results, TN is higher than Tc for the quantum anisotropic Heisenberg limit and TN= Tc for the Ising and quantum XY limits. We have also shown that the thermal critical exponent Yt for the isotropic Heisenberg model shows a small dependence on the type of interaction (F or AF) due to finite size effects.
Liu, Haiyang; Pang, Meixia; Yu, Xiaomu; Zhou, Ying; Tong, Jingou; Fu, Beide
2018-01-05
Sex-specific markers are powerful tools for identifying sex-determination system in various animals. Bighead carp (Hypophthalmichehys nobilis) and silver carp (Hypophthalmichthys molitrix) are two of the most important edible fish in Asia, which have a long juvenility period that can lasts for 4-5 years. In this study, we found one sex-specific marker by next-generation sequencing together with bioinformatics analysis in bighead carp. The male-specific markers were used to perform molecular sexing in the progenies of artificial gynogenetic diploids and found all progenies (n = 160) were females. Meanwhile, around 1 : 1 sex ratio was observed in a total of 579 juvenile offspring from three other families. To further extend the male-specific region, we performed genome walking and got a male-specific sequence of 8,661 bp. Five pairs of primers were designed and could be used to efficiently distinguish males from females in bighead carp and silver carp. The development of these male-specific markers and results of their molecular sexing in different populations provide strong evidence for a sex determination system of female homogametry or male heterogametry (XX/XY) in bighead carp and silver carp. To the best of our knowledge, this is the first report of effective sex-specific markers in these two large carp species. © The Author(s) 2018. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.
Temperature-dependent pitch and phase diagram for incommensurate XY spins in a slab geometry
International Nuclear Information System (INIS)
Collins, M.; Saslow, W.M.
1996-01-01
Strain-engineered Heisenberg antiferromagnets recently have been produced by controlling the layer thickness of MnSe/ZnTe superlattices. Neutron-scattering studies reveal a spiral that tends to untwist with increasing temperature. To simulate this system, we employ an XY model with nearest- and second-nearest neighbor antiferromagnetic interactions. The bulk mean-field phase diagram has four possible phases, for the full range of the exchange constants. Monte Carlo calculations are performed for a slab geometry, using an algorithm that allows the system to choose incommensurate boundary conditions. The phase diagram is constructed by monitoring the spiral pitch as a function of temperature for a range of exchange constants. For appropriate exchange constants, good agreement is obtained with experiment. From the mean-field phase diagram it appears that strain engineering an NaCl structure in a superlattice configuration might produce a type of spiral phase, and an associated antiferromagnetic-to-spiral phase transition. copyright 1996 The American Physical Society
Cosmological implications of Heisenberg's principle
Gonzalo, Julio A
2015-01-01
The aim of this book is to analyze the all important implications of Heisenberg's Uncertainty Principle for a finite universe with very large mass-energy content such as ours. The earlier and main contributors to the formulation of Quantum Mechanics are briefly reviewed regarding the formulation of Heisenberg's Principle. After discussing “indeterminacy” versus ”uncertainty”, the universal constants of physics are reviewed and Planck's units are given. Next, a novel set of units, Heisenberg–Lemaitre units, are defined in terms of the large finite mass of the universe. With the help of Heisenberg's principle, the time evolution of the finite zero-point energy for the universe is investigated quantitatively. Next, taking advantage of the rigorous solutions of Einstein's cosmological equation for a flat, open and mixed universe of finite mass, the most recent and accurate data on the “age” (to) and the expansion rate (Ho) of the universe and their implications are reconsidered.
Heisenberg, his wife s account
International Nuclear Information System (INIS)
Heisenberg, E.
1990-01-01
A wife tells about her husband life, Werner Heisenberg, Physics Nobel Price in 1932. After a happy childhood, this brilliant student was Albert Einstein, Niels Bohr, Arnold Sommerfeld s student. But at the nazism time, the great physician refused to leave his country, guaranteeing the Hitler regime and taking part in effort of war, that is to say the run to the bomb. The account of Elisabeth Heisenberg, although subjective, allows to understand the scientist s behaviour face terrifying realities of his time. (N.C.)
Entanglement in the XY spin chain
International Nuclear Information System (INIS)
Its, A R; Jin, B-Q; Korepin, V E
2005-01-01
We consider the entanglement in the ground state of the XY model of an infinite chain. Following Bennett, Bernstein, Popescu and Schumacher, we use the entropy of a sub-system as a measure of entanglement. Vidal, Latorre, Rico and Kitaev have conjectured that the von Neumann entropy of a large block of neighbouring spins approaches a constant as the size of the block increases. We evaluate this limiting entropy as a function of anisotropy and transverse magnetic field. We use the methods based on the integrable Fredholm operators and the Riemann-Hilbert approach. It is shown how the entropy becomes singular at the phase transition points
Energy Technology Data Exchange (ETDEWEB)
Rudowicz, Czesław, E-mail: crudowicz@zut.edu.pl
2014-03-01
Heisenberg antiferromagnetic chains based on Ni{sup 2+} ions with integer spin S=1 exhibit intriguing behavior, e.g. the Haldane gap phase and the large-D phase. The predicted transitions between the two phases and the Neel phase has generated search for real candidate systems. Crucial to this search is the interplay between the ‘in-plane anisotropy’, i.e. the rhombic zero-field splitting (ZFS) E-term, and the ‘planar anisotropy’, i.e. the axial ZFS D-term. This paper clarifies intricate properties of orthorhombic ZFS Hamiltonians (H{sub ZFS}) and inconsistencies revealed by critical survey of pertinent studies. Reporting the non-standard (D, E) sets with λ=E/D out of the standard range (0, 1/3) alongside the standard sets with λ∝(0, 1/3) indicates that these properties are not recognized. We show that direct comparisons of the non-standard and standard sets are meaningless and lead to incorrect conclusions on the strength of the ‘in-plane anisotropy’ (E) as compared with the ‘planar anisotropy’ (D). To remedy such problems, the ZFSP sets reported for the large-D phase candidate systems are reanalyzed using orthorhombic standardization. The six physically equivalent ZFSP sets are determined in the conventional (D, E) and Stevens (b{sub 2}{sup 0}, b{sub 2}{sup 2}) notation. These considerations help understanding intricacies inherent in orthorhombic H{sub ZFS} and provide consistent data for future modeling of ZFS parameters in the large-D phase and Haldane gap systems.
Non-Hermitian Heisenberg representation
Czech Academy of Sciences Publication Activity Database
Znojil, Miloslav
2015-01-01
Roč. 379, č. 36 (2015), s. 2013-2017 ISSN 0375-9601 Institutional support: RVO:61389005 Keywords : quantum mechanics * Non-Hermitian representation of observables * Generalized Heisenberg equations Subject RIV: BE - Theoretical Physics Impact factor: 1.677, year: 2015
Werner Heisenberg - Life and Work
2002-01-01
Werner Heisenberg (centre) with Wolfgang Pauli and Enrico Fermi, 1927. An exhibition on the life and work of Werner Heisenberg will be on display in the Main Building (Mezzanine) at CERN from 1 - 30 July*. German theoretical physicist Werner Karl Heisenberg (1901 - 1976) was one of the leading scientists of the 20th century. Nobel Prize in Physics in 1932, his most significant contribution was to the development of quantum mechanics. He is best known for his uncertainty principle, which restricts the accuracy with which some properties of atoms and particles can be determined simultaneously. Heisenberg was a keen supporter of CERN, and was as the first chairman of CERN's Scientific Policy Committee in October 1954. A related celebration will take place in the TH Amphitheatre (4/3-006), on Thursday 18 July at 16:00. After an introduction from the Director-General Luciano Maiani, his daughter, Barbara Blum, his last postgraduate, Helmut Rechenberg and Valentin Telegdi will evoke memories of the life and work ...
Werner Heisenberg - Life and Work
2002-01-01
Werner Heisenberg (centre) with Wolfgang Pauli (left) and Enrico Fermi on Lake Como, September 1927. An exhibition on the life and work of Werner Heisenberg will be on display in the Main Building (Mezzanine) at CERN from 1 - 23 July. The exhibition was produced by the University Archive of Leipzig University (Gerald Wiemers) and the Max-Planck-Institut für Physik in Munich (Helmut Rechenberg) to mark the centenary of Heisenberg's birth in 1901. German theoretical physicist Werner Karl Heisenberg (5 December 1901 - 1 February 1976) was one of the leading scientists of the 20th century. He carried out important work in nuclear and particle physics, but his most significant contribution was to the development of quantum mechanics. He is best known for his uncertainty principle, which restricts the accuracy with which some properties of atoms and particles - such as position and linear momentum - can be determined simultaneously. In 1932 he was awarded the Noble Prize in Physics 'for the creation of q...
Heisenberg's heirs exploit loopholes in his law
International Nuclear Information System (INIS)
Taubes, G.
1994-01-01
This article describes research into Heisenberg's Uncertainty Principle. Loopholes in the principle have led to a series of experiments using sophisticated optical techniques to extract information from a quantum system without disturbing the variable being measured. The experiments are based on a technique called back-action evasion, which exploits the possibility of channeling all the uncertainty generated by measuring one quantum variable (e.g. laser beam intensity) onto a related variable known as the conjugate observable (beam phase). These experiments and others are described
Quantum Fourier transform, Heisenberg groups and quasi-probability distributions
International Nuclear Information System (INIS)
Patra, Manas K; Braunstein, Samuel L
2011-01-01
This paper aims to explore the inherent connection between Heisenberg groups, quantum Fourier transform (QFT) and (quasi-probability) distribution functions. Distribution functions for continuous and finite quantum systems are examined from three perspectives and all of them lead to Weyl-Gabor-Heisenberg groups. The QFT appears as the intertwining operator of two equivalent representations arising out of an automorphism of the group. Distribution functions correspond to certain distinguished sets in the group algebra. The marginal properties of a particular class of distribution functions (Wigner distributions) arise from a class of automorphisms of the group algebra of the Heisenberg group. We then study the reconstruction of the Wigner function from the marginal distributions via inverse Radon transform giving explicit formulae. We consider some applications of our approach to quantum information processing and quantum process tomography.
Integrable higher order deformations of Heisenberg supermagnetic model
International Nuclear Information System (INIS)
Guo Jiafeng; Yan Zhaowen; Wang Shikun; Wu Ke; Zhao Weizhong
2009-01-01
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 2 =3S-2I for S is an element of USPL(2/1)/S(U(2)xU(1)) and (ii) S 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.
Quasi-Linear Algebras and Integrability (the Heisenberg Picture
Directory of Open Access Journals (Sweden)
Alexei Zhedanov
2008-02-01
Full Text Available 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.
Heisenberg picture and measurement operation
International Nuclear Information System (INIS)
D'Espagnat, B.
1992-01-01
The idea is discussed according to which, in the Heisenberg picture, differently from the Schroedinger picture, the operators correspond exactly to the dynamic properties and the role of the density matrix is merely to describe our passive knowledge thereof. It is shown that the idea in question cannot be consistently kept as it is, and hints are given as to how it could be refined. (from author). 2 refs
Generalized Heisenberg algebra and (non linear) pseudo-bosons
Bagarello, F.; Curado, E. M. F.; Gazeau, J. P.
2018-04-01
We propose a deformed version of the generalized Heisenberg algebra by using techniques borrowed from the theory of pseudo-bosons. In particular, this analysis is relevant when non self-adjoint Hamiltonians are needed to describe a given physical system. We also discuss relations with nonlinear pseudo-bosons. Several examples are discussed.
Heisenberg and the framework of science policy
International Nuclear Information System (INIS)
Carson, C.
2002-01-01
In the decades after 1945, new structures were created for science policy in the Federal Republic. To the establishment of the postwar framework Heisenberg contributed as much as any other figure. This was true even though, on the whole, he took no great pleasure in the venture, nor was he always particularly adept at it. His conceptions revolved around certain key notions: autonomy and centralization, elite advisory bodies and relationships of trust, modernization and international standards. These show up at many levels of his activity, from the Max Planck Society to national and international advisory committees to the Humboldt Foundation itself. His opinions were shaped by encounters in the Federal Republic, but they also grew out of his experience of the Third Reich. At a moment like the present, when the postwar settlement is under review, it is interesting to reflect on the inherited system: on the extent to which it reflects the situation of the postwar decades and the intuitions of those who, like Heisenberg, created it. (orig.)
A quaternionic map for the steady states of the Heisenberg spin-chain
Energy Technology Data Exchange (ETDEWEB)
Mehta, Mitaxi P., E-mail: mitaxi.mehta@ahduni.edu.in [IICT, Ahmedabad University, Opp. IIM, Navrangpura, Ahmedabad (India); Dutta, Souvik; Tiwari, Shubhanshu [BITS-Pilani, K.K. Birla Goa campus, Goa (India)
2014-01-17
We show that the steady states of the classical Heisenberg XXX spin-chain in an external magnetic field can be found by iterations of a quaternionic map. A restricted model, e.g., the xy spin-chain is known to have spatially chaotic steady states and the phase space occupied by these chaotic states is known to go through discrete changes as the field strength is varied. The same phenomenon is studied for the xxx spin-chain. It is seen that in this model the phase space volume varies smoothly with the external field.
A quaternionic map for the steady states of the Heisenberg spin-chain
International Nuclear Information System (INIS)
Mehta, Mitaxi P.; Dutta, Souvik; Tiwari, Shubhanshu
2014-01-01
We show that the steady states of the classical Heisenberg XXX spin-chain in an external magnetic field can be found by iterations of a quaternionic map. A restricted model, e.g., the xy spin-chain is known to have spatially chaotic steady states and the phase space occupied by these chaotic states is known to go through discrete changes as the field strength is varied. The same phenomenon is studied for the xxx spin-chain. It is seen that in this model the phase space volume varies smoothly with the external field.
XY model with higher-order exchange.
Žukovič, Milan; Kalagov, Georgii
2017-08-01
An XY model, generalized by inclusion of up to an infinite number of higher-order pairwise interactions with an exponentially decreasing strength, is studied by spin-wave theory and Monte Carlo simulations. At low temperatures the model displays a quasi-long-range-order phase characterized by an algebraically decaying correlation function with the exponent η=T/[2πJ(p,α)], nonlinearly dependent on the parameters p and α that control the number of the higher-order terms and the decay rate of their intensity, respectively. At higher temperatures the system shows a crossover from the continuous Berezinskii-Kosterlitz-Thouless to the first-order transition for the parameter values corresponding to a highly nonlinear shape of the potential well. The role of topological excitations (vortices) in changing the nature of the transition is discussed.
Deformation quantization of the Heisenberg group
International Nuclear Information System (INIS)
Bonechi, F.
1994-01-01
After reviewing the way the quantization of Poisson Lie Groups naturally leads to Quantum Groups, the existing quantum version H(1) q of the Heisenberg algebra is used to give an explicit example of this quantization on the Heisenberg group. (author) 6 refs
Werner Karl Heisenberg (1901-1976)
International Nuclear Information System (INIS)
Kvasnica, J.
1992-01-01
The life's career of Werner Karl Heisenberg is described with emphasis on his creative development and cooperation with many other prominent physicists in the field of the quantum theory of atoms. In 1925, Heisenberg modified Bohr's quantum rule; in 1927 he formulated the uncertainty principle which puts some restrictions on the simultaneous determination of the position and momentum. In 1928, Heisenberg set up the quantum theory of ferromagnetism, which still underlies all theories of magnetic properties of substances. Soon after Chadwick's discovery of the neutron (1932), Heisenberg introduced the concept of the isospin - he interpreted the proton and the neutron as one particle (nucleon) in two charge states. Heisenberg's professional and pedagogical activities during and after the 2nd world war are also described. (Z.S.). 5 refs
Care of women with XY karyotype
DEFF Research Database (Denmark)
Jorgensen, Pernille Bach; Kjartansdóttir, Kristín Rós; Fedder, Jens
2010-01-01
OUTCOME MEASURE(S): Evaluation of etiology, diagnosis, treatment, and associated disorders in XY women. RESULT(S): Many gene mutations can cause abnormal fetal development leading to androgen insensitivity syndrome or gonadal dysgenesis disorders. Females with these disorders have an XY karyotype but look...... like girls. They are mostly diagnosed at puberty, and the condition will often lead to serious psychological problems. Increased risk of malignancies and problems with pregnancy and infertility are other aspects that should be considered. This guideline will aid doctors in caring for XY females...
Etiological Diagnosis of Undervirilized Male / XY Disorder of Sex Development
International Nuclear Information System (INIS)
Atta, I.; Ibrahim, M.; Parkash, A.; Lone, S. W.; Khan, Y. N.; Raza, J.
2014-01-01
Objective: To do clinical, hormonal and chromosomal analysis in undervirilized male / XY disorder of sex development and to make presumptive etiological diagnosis according to the new Disorder of Sex Development (DSD) classification system. Study Design: Case series. Place and Duration of Study: Endocrine Unit at National Institute of Child Health, Karachi, Pakistan, from January 2007 to December 2012. Methodology: Patients of suspected XY DSD / undervirilized male visiting endocrine clinic were enrolled in the study. Criteria suggested XY DSD include overt genital ambiguity, apparent female/male genitalia with inguinal/labial mass, apparent male genitalia with unilateral or bilateral non-palpable testes, micropenis and isolated hypospadias or with undescended testis. The older children who had delayed puberty were also evaluated with respect to DSD. As a part of evaluation of XY DSD, abdominopelvic ultrasound, karyotype, hormone measurement (testosterone, FSH, LH), FISH analysis with SRY probing, genitogram, laparoscopy, gonadal biopsy and HCG stimulation test were performed. Frequencies and percentages applied on categorical data whereas mean, median, standard deviation were calculated for continuous data. Results: A total of 187 patients met the criteria of XY DSD. Age ranged from 1 month to 15 years, 55 (29.4%) presented in infancy, 104 (55.6%) between 1 and 10 years and 28 (15%) older than 10 years. Twenty five (13.4%) were raised as female and 162 as (86.6%) male. The main complaints were ambiguous genitalia, unilateral cryptorchidism, bilateral cryptorchidism, micropenis, delayed puberty, hypospadias, female like genitalia with gonads, inguinal mass. The karyotype was 46 XY in 183 (97.9%), 46 XX in 2 (1.1%), 47 XXY in 1 (0.5%), 45 X/46 XY in 1 (0.5%) patient. HCG stimulation test showed low testosterone response in 43 (23 %), high testosterone response in 62 (33.2%), partial testosterone response in 32 (17.1%) and normal testosterone response in 50 (26
Local quantum control of Heisenberg spin chains
International Nuclear Information System (INIS)
Heule, Rahel; Bruder, C.; Stojanovic, Vladimir M.; Burgarth, Daniel
2010-01-01
Motivated by some recent results of quantum control theory, we discuss the feasibility of local operator control in arrays of interacting qubits modeled as isotropic Heisenberg spin chains. Acting on one of the end spins, we aim at finding piecewise-constant control pulses that lead to optimal fidelities for a chosen set of quantum gates. We analyze the robustness of the obtained results for the gate fidelities to random errors in the control fields, finding that with faster switching between piecewise-constant controls the system is less susceptible to these errors. The observed behavior falls into a generic class of physical phenomena that are related to a competition between resonance- and relaxation-type behavior, exemplified by motional narrowing in NMR experiments. Finally, we discuss how the obtained optimal gate fidelities are altered when the corresponding rapidly varying piecewise-constant control fields are smoothened through spectral filtering.
Entanglement of periodic anisotropic XY chains
International Nuclear Information System (INIS)
Zhang Lifa; Tong Peiqing
2005-01-01
By using the concept of concurrence, the entanglement of periodic anisotropic XY chains in a transverse field is studied numerically. It is found that the derivatives ∂ λ C(1) of nearest-neighbour concurrence diverge at quantum critical points. By proper scaling, we found that all the derivatives ∂ λ C(1) for periodic XY chains in the vicinity of quantum critical points have the same behaviours as that of a uniform chain
At the Limits of Criticality-Based Quantum Metrology: Apparent Super-Heisenberg Scaling Revisited
Rams, Marek M.; Sierant, Piotr; Dutta, Omyoti; Horodecki, Paweł; Zakrzewski, Jakub
2018-04-01
We address the question of whether the super-Heisenberg scaling for quantum estimation is indeed realizable. We unify the results of two approaches. In the first one, the original system is compared with its copy rotated by the parameter-dependent dynamics. If the parameter is coupled to the one-body part of the Hamiltonian, the precision of its estimation is known to scale at most as N-1 (Heisenberg scaling) in terms of the number of elementary subsystems used N . The second approach compares the overlap between the ground states of the parameter-dependent Hamiltonian in critical systems, often leading to an apparent super-Heisenberg scaling. However, we point out that if one takes into account the scaling of time needed to perform the necessary operations, i.e., ensuring adiabaticity of the evolution, the Heisenberg limit given by the rotation scenario is recovered. We illustrate the general theory on a ferromagnetic Heisenberg spin chain example and show that it exhibits such super-Heisenberg scaling of ground-state fidelity around the critical value of the parameter (magnetic field) governing the one-body part of the Hamiltonian. Even an elementary estimator represented by a single-site magnetization already outperforms the Heisenberg behavior providing the N-1.5 scaling. In this case, Fisher information sets the ultimate scaling as N-1.75, which can be saturated by measuring magnetization on all sites simultaneously. We discuss universal scaling predictions of the estimation precision offered by such observables, both at zero and finite temperatures, and support them with numerical simulations in the model. We provide an experimental proposal of realization of the considered model via mapping the system to ultracold bosons in a periodically shaken optical lattice. We explicitly derive that the Heisenberg limit is recovered when the time needed for preparation of quantum states involved is taken into account.
Quenched disorder and spin-glass correlations in XY nematics
International Nuclear Information System (INIS)
Petridis, L; Terentjev, E M
2006-01-01
We present a theoretical study of the equilibrium ordering in a 3D XY nematic system with quenched random disorder. Within this model, treated with the replica trick and Gaussian variational method, the correlation length is obtained as a function of the local nematic order parameter Q and the effective disorder strength Γ. These results, ξ ∼ Q 2 e 1/Q 2 and ξ ∼ (1/Γ) e -Γ , clarify what happens in the limiting cases of diminishing Q and Γ, that is near a phase transition of a pure system. In particular, it is found that quenched disorder is irrelevant as Q → 0 and hence does not change the character of the continuous XY nematic-isotropic phase transition. We discuss how these results compare with experiments and simulations
Theory for disordered phase in Heisenberg and non-Heisenberg two-dimensional S=1 ferromagnets
International Nuclear Information System (INIS)
Spirin, D.V.; Fridman, Yu.A.
2003-01-01
We apply a modification of self-consistent spin-wave theory to investigation of two-dimensional S=1 isotropic Heisenberg and non-Heisenberg ferromagnets at nonzero temperatures. We use Hubbard operators method and bosonization technique. We calculated chemical potential and found dependence of correlation length on temperature. Specific heat has Schottky-type peak and decreases at high temperatures. Disordered phase in non-Heisenberg ferromagnet is also studied. The results for such a model differ from those of Heisenberg one
Quantum Heisenberg groups and Sklyanin algebras
International Nuclear Information System (INIS)
Andruskiewitsch, N.; Devoto, J.; Tiraboschi, A.
1993-05-01
We define new quantizations of the Heisenberg group by introducing new quantizations in the universal enveloping algebra of its Lie algebra. Matrix coefficients of the Stone-von Neumann representation are preserved by these new multiplications on the algebra of functions on the Heisenberg group. Some of the new quantizations provide also a new multiplication in the algebra of theta functions; we obtain in this way Sklyanin algebras. (author). 23 refs
Correlation functions of heisenberg-mattis model in one dimension
International Nuclear Information System (INIS)
Azeeem, W.
1991-01-01
The technique of real-space renormalization to the dynamics of Heisenberg-Mattis model, which represents a random magnetic system with competing ferromagnetic and antiferromagnetic interactions has been applied. The renormalization technique, which has been in use for calculating density of states, is extended to calculate dynamical response function from momentum energy dependent Green's functions. Our numerical results on density of states and structure function of one-dimensional Heisenberg-Mattis model come out to be in good agreement with computer simulation results. The numerical scheme worked out in this thesis has the advantage that it can also provide a complete map of momentum and energy dependence of the structure function. (author)
Applications of the Heisenberg magnetic model in nanoscience
International Nuclear Information System (INIS)
Labuz, M.; Kuzma, M.; Wal, A.
2003-01-01
The theoretical Heisenberg magnet model and its solution given by Bethe and Hulthen (B.H.) known as Bethe Ansatz (BA) is widely applied in physics (solid state physics, quantum dots, statistical physics, high-temperatures superconductivity, low-dimensional systems, etc.), chemistry (polymers, organic metals and magnets), biology (biological molecular arrays and chains), etc. In most of the applications, the Heisenberg model is applied to infinite chains (asymptotic case), which is a good reality approximation for objects of macroscopic size. In such a case, the solutions of the model are well known. However, for objects of nanoscale size, one has to find solutions of the Heisenberg model of a finite chain consisting of N nodes. For such a chain, the problem of solving of B.H. equations is very complicated (because of the strange nonlinearity of these equations) even for very small objects N N (combinatorial explosion). In such cases, even numerical methods are helpless. In our paper, we propose an approach in which numerical methods could be adapted to such a large numerical problem, as B.H. solutions for objects consisting of N>100, which responds to nanoscale physical or biological objects. This method is based on the 'experimental' observation that B.H. solutions change in a quasi-continuous way with respect to N
Photoelectric elements of the eclipsing binary XY Ceti
International Nuclear Information System (INIS)
Srivastava, R.K.; Padalia, T.D.
1975-01-01
The absolute elements of the system XY Ceti have been obtained on the basis of the spectroscopic elements given by Popper (1971) and the photoelectric elements derived previously. The colours of the components have been obtained. Both components are found to lie fairly on the Main Sequence. The primary component of the system, however, is slightly more evolved as it shows a tendency to drift away from the Main Sequence. The spectral classes now assigned are A5V (primary) and A7V (secondary). The values of Roche constants indicate that the system is a detached one. (Auth.)
Excitation spectrum of Heisenberg spin ladders
International Nuclear Information System (INIS)
Barnes, T.; Dagotto, E.; Riera, J.; Swanson, E.S.
1993-01-01
Heisenberg antiferromagnetic spin ''ladders'' (two coupled spin chains) are low-dimensional magnetic systems which for S=1/2 interpolate between half-integer-spin chains, when the chains are decoupled, and effective integer-spin one-dimensional chains in the strong-coupling limit. The spin-1/2 ladder may be realized in nature by vanadyl pyrophosphate, (VO) 2 P 2 O 7 . In this paper we apply strong-coupling perturbation theory, spin-wave theory, Lanczos techniques, and a Monte Carlo method to determine the ground-state energy and the low-lying excitation spectrum of the ladder. We find evidence of a nonzero spin gap for all interchain couplings J perpendicular >0. A band of spin-triplet excitations above the gap is also analyzed. These excitations are unusual for an antiferromagnet, since their long-wavelength dispersion relation behaves as (k-k 0 ) 2 (in the strong-coupling limit J perpendicular much-gt J, where J is the in-chain antiferromagnetic coupling). Their band is folded, with a minimum energy at k 0 =π, and a maximum between k 1 =π/2 (for J perpendicular =0) and 0 (for J perpendicular =∞). We also give numerical results for the dynamical structure factor S(q,ω), which can be determined in neutron scattering experiments. Finally, possible experimental techniques for studying the excitation spectrum are discussed
The Heisenberg picture for single photon states
International Nuclear Information System (INIS)
Pienaar, Jacques; Myers, Casey; Ralph, Timothy C.
2011-01-01
In the context of quantum field theory, the Heisenberg picture has a distinct advantage over the Schrodinger picture because the Schrodinger picture requires us to transform the vacuum state itself, which can be intractable in the case of non-inertial reference frames, whereas the Heisenberg picture allows us to keep the same vacuum state and only transform the operators. However, the Heisenberg calculation requires the operators to already be expressed as a function of creation and annihilation operators acting on the original vacuum, whereas calculations in quantum information and quantum computation use operators that act on qubit states, necessarily containing particles. The relationship between the operators acting on these states and the operators acting on the vacuum state has remained elusive. We derive such an expression using an explicit model for single-particle production from the vacuum.
Zhang, Zuo-Yuan; Wei, DaXiu; Liu, Jin-Ming
2018-06-01
The precision of measurements for two incompatible observables in a physical system can be improved with the assistance of quantum memory. In this paper, we investigate the quantum-memory-assisted entropic uncertainty relation for a spin-1 Heisenberg model in the presence of external magnetic fields, the systemic quantum entanglement (characterized by the negativity) is analyzed as contrast. Our results show that for the XY spin chain in thermal equilibrium, the entropic uncertainty can be reduced by reinforcing the coupling between the two particles or decreasing the temperature of the environment. At zero-temperature, the strong magnetic field can result in the growth of the entropic uncertainty. Moreover, in the Ising case, the variation trends of the uncertainty are relied on the choices of anisotropic parameters. Taking the influence of intrinsic decoherence into account, we find that the strong coupling accelerates the inflation of the uncertainty over time, whereas the high magnetic field contributes to its reduction during the temporal evolution. Furthermore, we also verify that the evolution behavior of the entropic uncertainty is roughly anti-correlated with that of the entanglement in the whole dynamical process. Our results could offer new insights into quantum precision measurement for the high spin solid-state systems.
I grandi della fisica da Platone a Heisenberg
Von Weizsäcker, Carl Friedrich
2002-01-01
Parmenide ; Platone ; Aristotele ; Copernico, Keplero, Galilei ; Galileo Galilei ; Cartesio ; Gottfried Wilhelm Leibniz ; Cartesio, Newton, Leibniz, Kant ; Immanuel Kant ; Johann Wolfgang Goethe ; Robert Meyer ; Albert Einstein ; Niels Bohr ; Paul Adrien Maurice Dirac ; Niels Bohr e Werner Heisenberg, un ricordo del 1932 ; Werner Heisenberg ; Heisenberg, fisico e filosofo ; l'interpretazione filosofica della fisica moderna.
Remarks on Heisenberg-Euler-type electrodynamics
Kruglov, S. I.
2017-05-01
We consider Heisenberg-Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg-Euler electrodynamics is a particular case of this model. Corrections to Coulomb’s law at r →∞ are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at r →∞. Corrections to the Reissner-Nordström solution are obtained.
Hilbert schemes of points and Heisenberg algebras
International Nuclear Information System (INIS)
Ellingsrud, G.; Goettsche, L.
2000-01-01
Let X [n] be the Hilbert scheme of n points on a smooth projective surface X over the complex numbers. In these lectures we describe the action of the Heisenberg algebra on the direct sum of the cohomologies of all the X [n] , which has been constructed by Nakajima. In the second half of the lectures we study the relation of the Heisenberg algebra action and the ring structures of the cohomologies of the X [n] , following recent work of Lehn. In particular we study the Chern and Segre classes of tautological vector bundles on the Hilbert schemes X [n] . (author)
Conde-Saldaña, Cristhian Camilo; Barreto, Cynthia Aparecida Valiati; Villa-Navarro, Francisco Antonio; Dergam, Jorge Abdala
2018-02-01
This work constitutes the first cytogenetic characterization of a trans-Andean species of Heptapteridae. The catfish Pimelodella cf. chagresi from the Upper Rio Magdalena was studied, applying standard cytogenetic techniques (Giemsa, C-banding, and argyrophilic nucleolar organizer region [Ag-NOR]) and fluorescence in situ hybridization techniques using repetitive DNA probes: microsatellites (CA 15 and GA 15 ) and ribosomal RNA (rRNA) multigene families (18S and 5S recombinant DNA [rDNA] probes). The species showed a unique diploid chromosome number 2n = 50 (32m [metacentrics] +14sm [submetacentrics] +4st [subtelocentrics]) and a XX/XY sex chromosomal system, where the heteromorphic Y-chromosome revealed a conspicuous accumulation of all the assayed domains of repetitive DNA. P. cf. chagresi karyotype shares common features with other Heptapteridae, such as the predominance of metacentric and submetacentric chromosomes, and one pair of subtelomeric nucleolar organizer regions (NORs). These results reflect an independent karyological identity of a trans-Andean species and the relevance of repetitive DNA sequences in the process of sex chromosome differentiation in fish; it is the first case of syntenic accumulation of rRNA multigene families (18S and 5S rDNA) and microsatellite sequences (CA 15 and GA 15 ) in a differentiated sex chromosome in Neotropical fish.
InXy and SeXy, compact heterologous reporter proteins for mammalian cells.
Fluri, David A; Kelm, Jens M; Lesage, Guillaume; Baba, Marie Daoud-El; Fussenegger, Martin
2007-10-15
Mammalian reporter proteins are essential for gene-function analysis, drugscreening initiatives and as model product proteins for biopharmaceutical manufacturing. Bacillus subtilis can maintain its metabolism by secreting Xylanase A (XynA), which converts xylan into shorter xylose oligosaccharides. XynA is a family 11 xylanase monospecific for D-xylose containing substrates. Mammalian cells transgenic for constitutive expression of wild-type xynA showed substantial secretion of this prokaryotic enzyme. Deletion analysis confirmed that a prokaryotic signal sequence encoded within the first 81 nucleotides was compatible with the secretory pathway of mammalian cells. Codon optimization combined with elimination of the prokaryotic signal sequence resulted in an exclusively intracellular mammalian Xylanase A variant (InXy) while replacement by an immunoglobulin-derived secretion signal created an optimal secreted Xylanase A derivative (SeXy). A variety of chromogenic and fluorescence-based assays adapted for use with mammalian cells detected InXy and SeXy with high sensitivity and showed that both reporter proteins resisted repeated freeze/thaw cycles, remained active over wide temperature and pH ranges, were extremely stable in human serum stored at room temperature and could independently be quantified in samples also containing other prominent reporter proteins such as the human placental alkaline phosphatase (SEAP) and the Bacillus stearothermophilus-derived secreted alpha-amylase (SAMY). Glycoprofiling revealed that SeXy produced in mammalian cells was N- glycosylated at four different sites, mutation of which resulted in impaired secretion. SeXy was successfully expressed in a variety of mammalian cell lines and primary cells following transient transfection and transduction with adeno-associated virus particles (AAV) engineered for constitutive SeXy expression. Intramuscular injection of transgenic AAVs into mice showed significant SeXy levels in the bloodstream
Simulation of time-dependent Heisenberg models in one dimension
DEFF Research Database (Denmark)
Volosniev, A. G.; Hammer, H. -W.; Zinner, N. T.
2016-01-01
In this Letter, we provide a theoretical analysis of strongly interacting quantum systems confined by a time-dependent external potential in one spatial dimension. We show that such systems can be used to simulate spin chains described by Heisenberg Hamiltonians in which the exchange coupling...... constants can be manipulated by time-dependent driving of the shape of the external confinement. As illustrative examples, we consider a harmonic trapping potential with a variable frequency and an infinite square well potential with a time-dependent barrier in the middle....
XY females do better than the XX in the African pygmy mouse, Mus minutoides.
Saunders, Paul A; Perez, Julie; Rahmoun, Massilva; Ronce, Ophélie; Crochet, Pierre-André; Veyrunes, Frédéric
2014-07-01
All therian mammals have a similar XY/XX sex-determination system except for a dozen species. The African pygmy mouse, Mus minutoides, harbors an unconventional system in which all males are XY, and there are three types of females: the usual XX but also XX* and X*Y ones (the asterisk designates a sex-reversal mutation on the X chromosome). The long-term evolution of such a system is a paradox, because X*Y females are expected to face high reproductive costs (e.g., meiotic disruption and loss of unviable YY embryos), which should prevent invasion and maintenance of a sex-reversal mutation. Hence, mechanisms for compensating for the costs could have evolved in M. minutoides. Data gathered from our laboratory colony revealed that X*Y females do compensate and even show enhanced reproductive performance in comparison to the XX and XX*; they produce significantly more offspring due to (i) a higher probability of breeding, (ii) an earlier first litter, and (iii) a larger litter size, linked to (iv) a greater ovulation rate. These findings confirm that rare conditions are needed for an atypical sex-determination mechanism to evolve in mammals, and provide valuable insight into understanding modifications of systems with highly heteromorphic sex chromosomes. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
Polarizability tensor and Kramers-Heisenberg induction
Wijers, Christianus M.J.
2004-01-01
A general expression for the semiclassical, nonrelativistic linear polarizability of an arbitrary volume element V has been derived in the long wavelength approximation. The derivation starts from the expectation value of the dipole strength, as in the original Kramers-Heisenberg paper about optical
Uncertainty inequalities for the Heisenberg group
Indian Academy of Sciences (India)
where φ is an admissible wavelet and kφ is an appropriate positive constant. For more on the history and the relevance of the uncertainty inequality, we refer the readers to the survey [5], the books [6,8], and the papers [2,10,11]. For the Heisenberg group Hn, Thangavelu [16] proved the following theorem. Theorem 1.1.
Boeij, de J.; Lomonova, E.A.; Duarte, J.L.; Vandenput, A.J.A.
2008-01-01
In this paper, a new topology for contactless energy transfer is proposed and tested that can transfer energy to a moving load using inductive coupling. This contactless energy transfer topology is designed to supply power to the moving parts in high-precision mechatronic systems without cable
Graphics of (X,Y) spectrum for microcomputer; Graficado de espectro (X,Y) para microcomputadora
Energy Technology Data Exchange (ETDEWEB)
Macias B, L.R
1991-08-15
When carrying out diffraction works is frequently required to visualize the spectra of the data obtained in order to analyzing them. The design for the obtaining of data in the neutron diffractometer by means of the microcomputer allows to store them in a file by means of the one which transferring to the CYBER system so that by means of its utilities the mentioned spectrum is observed in a graph. In diffraction works, it is sought to study crystalline materials by means of the execution of the Bragg law by that the mounted sample on the diffractometer is subjected to a scanning of the sample with a radiation of a well-known wavelength and this way varying the angles, the corresponding interplanar distances are determined. The main objective of this work, is starting of a data set generated by the diffractometer, to generate the graph of the corresponding (X,Y) spectra in visual form in the screen of a microcomputer and if it is required, to obtain the graph in printed form by means of the same computer program for microcomputer. (Author)
Directory of Open Access Journals (Sweden)
Maxence S Vincent
2016-08-01
Full Text Available The Type IX secretion system (T9SS is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion of surface attachment of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY and PorX encode typical two-component system (TCS sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of the porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we showed that PorX does not bind and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS.
Vincent, Maxence S.; Durand, Eric; Cascales, Eric
2016-01-01
The Type IX secretion system (T9SS) is a versatile multi-protein complex restricted to bacteria of the Bacteriodetes phylum and responsible for the secretion or cell surface exposition of diverse proteins that participate to S-layer formation, gliding motility or pathogenesis. The T9SS is poorly characterized but a number of proteins involved in the assembly of the secretion apparatus in the oral pathogen Porphyromonas gingivalis have been identified based on genome substractive analyses. Among these proteins, PorY, and PorX encode typical two-component system (TCS) sensor and CheY-like response regulator respectively. Although the porX and porY genes do not localize at the same genetic locus, it has been proposed that PorXY form a bona fide TCS. Deletion of porX in P. gingivalis causes a slight decrease of the expression of a number of other T9SS genes, including sov, porT, porP, porK, porL, porM, porN, and porY. Here, we show that PorX and the soluble cytoplasmic domain of PorY interact. Using electrophoretic mobility shift, DNA-protein co-purification and heterologous host expression assays, we demonstrate that PorX does not bind T9SS gene promoters and does not directly regulate expression of the T9SS genes. Finally, we show that PorX interacts with the cytoplasmic domain of PorL, a component of the T9SS membrane core complex and propose that the CheY-like PorX protein might be involved in the dynamics of the T9SS. PMID:27630829
Spin-density functional for exchange anisotropic Heisenberg model
International Nuclear Information System (INIS)
Prata, G.N.; Penteado, P.H.; Souza, F.C.; Libero, Valter L.
2009-01-01
Ground-state energies for antiferromagnetic Heisenberg models with exchange anisotropy are estimated by means of a local-spin approximation made in the context of the density functional theory. Correlation energy is obtained using the non-linear spin-wave theory for homogeneous systems from which the spin functional is built. Although applicable to chains of any size, the results are shown for small number of sites, to exhibit finite-size effects and allow comparison with exact-numerical data from direct diagonalization of small chains.
International Nuclear Information System (INIS)
Ibort, A; Man'ko, V I; Marmo, G; Simoni, A; Ventriglia, F
2009-01-01
A natural extension of the Wigner function to the space of irreducible unitary representations of the Weyl-Heisenberg group is discussed. The action of the automorphisms group of the Weyl-Heisenberg group onto Wigner functions and their generalizations and onto symplectic tomograms is elucidated. Some examples of physical systems are considered to illustrate some aspects of the characterization of the Wigner functions as solutions of differential equations
Thermal excitations of frustrated XY spins in two dimensions
International Nuclear Information System (INIS)
Benakli, M.; Zheng, H.; Gabay, M.
1996-11-01
We present a new variational approach to the study of phase transitions in frustrated 2D XY models. In the spirit of Villain's approach for the ferromagnetic case we divide thermal excitations into a low temperature long wavelength part (LW) and a high temperature short wavelength part (SW). In the present work we mainly deal with LW excitations and we explicitly consider the cases of the fully frustrated triangular (FFTXY) and square (FFSQXY) XY models. The novel aspect of our method is that it preserves the coupling between phase (spin angles) and chiral degrees of freedom. LW fluctuations consist of coupled phase and chiral excitations. As a result, we find that for frustrated systems the effective interactions between phase variables is long range and oscillatory in contrast to the unfrustrated problem. Using Monte Carlo (MC) simulations we show that our analytical calculations produce accurate results at all temperature T; this is seen at low T in the spin wave stiffness constant and in the staggered chirality; this is also the case near T c : transitions are driven by the SW part associated with domain walls and vortices, but the coupling between phase and chiral variables is still relevant in the critical region. In that regime our analytical results yield the correct T dependence for bare couplings (given by the LW fluctuations) such as the Coulomb gas temperature T CG of the frustrated XY models. In particular, we find that T CG tracks chiral rather than phase fluctuations. Our results provide support for a single phase transition scenario in the FFTXY and FFSQXY models. (author). 35 refs, 8 figs
Dimensional crossover in the XY-compound YBa_{2}Cu_{3}O_{6}_{+}_{x}
DEFF Research Database (Denmark)
Montfrooij, W.; Casalta, H.; Schleger, P.
1998-01-01
The magnetic ordering of the bilayered Heisenberg antiferromagnet YBa2Cu3O6+x with weak XY-anisotropy was investigated for temperatures close to the magnetic transition temperature T-N. We find that the magnitude of the sublattice magnetization is well described by a power law similar to epsilon(0...... of the magnetic reflections (1/2h,1/2h,0), indicative of a small component of the electron moments perpendicular to the ab-plane. (C) 1998 Elsevier Science B.V. All rights reserved....
Chaotic dynamics of Heisenberg ferromagnetic spin chain with bilinear and biquadratic interactions
Blessy, B. S. Gnana; Latha, M. M.
2017-10-01
We investigate the chaotic dynamics of one dimensional Heisenberg ferromagnetic spin chain by constructing the Hamiltonian equations of motion. We present the trajectory and phase plots of the system with bilinear and also biquadratic interactions. The stability of the system is analysed in both cases by constructing the Jacobian matrix and by measuring the Lyapunov exponents. The results are illustrated graphically.
Ising critical behaviour in the one-dimensional frustrated quantum XY model
International Nuclear Information System (INIS)
Granato, E.
1993-06-01
A generalization of the one-dimensional frustrated quantum XY model is considered in which the inter and intra-chain coupling constants of the two infinite XY (planar rotor) chains have different strengths. The model can describe the superconductor-insulator transition due to charging effects in a ladder of Josephson junctions in a magnetic field with half a flux quantum per plaquette. From a fluctuation-effective action, this transition is expected to be in the universality class of the two-dimensional classical XY-Ising model. The critical behaviour is studied using a Monte Carlo transfer matrix applied to the path-integral representation of the model and a finite-size-scaling analysis of data on small system sizes. It is found that, unlike the previous studied case of equal inter and intra-chain coupling constants, the XY and Ising-like excitations of the quantum model decouple for large interchain coupling, giving rise to pure Ising model critical behaviour for the chirality order parameter in good agreement with the results for the XY-Ising model. (author). 18 refs, 4 figs
The Heisenberg antiferromagnet on the square-kagomé lattice
Directory of Open Access Journals (Sweden)
J. Richter
2009-01-01
Full Text Available We discuss the ground state, the low-lying excitations as well as high-field thermodynamics of the Heisenberg antiferromagnet on the two-dimensional square-kagomé lattice. This magnetic system belongs to the class of highly frustrated spin systems with an infinite non-trivial degeneracy of the classical ground state as it is also known for the Heisenberg antiferromagnet on the kagomé and on the star lattice. The quantum ground state of the spin-half system is a quantum paramagnet with a finite spin gap and with a large number of non-magnetic excitations within this gap. We also discuss the magnetization versus field curve that shows a plateaux as well as a macroscopic magnetization jump to saturation due to independent localized magnon states. These localized states are highly degenerate and lead to interesting features in the low-temperature thermodynamics at high magnetic fields such as an additional low-temperature peak in the specific heat and an enhanced magnetocaloric effect.
Considerations on Bohr's, Heisenberg's and Schroedinger's philosophy
International Nuclear Information System (INIS)
Shimony, A.
1981-01-01
In denying that the words 'physical reality' are meaningful without reference to an experimental arrangement, Bohr renounces any knowledge of the 'thing-in-itself'. However, the relation of his epistemology to both idealism and positivism remains obscure. Heisenberg departs from Bohr in enunciating a metaphysical implication of quantum mechanics. Heisenberg asserts that there is an intermediate modality -potentiality- between logical possibility and existence. His attempts to explain the transition from potentiality to existence are not convincing. Schroedinger rejects Bohr's interpretation of quantum mechanics as a positivist exercise and seeks instead a realist interpretation. Nevertheless, the metaphysics of Schroedinger is fundamentally idealistic, maintaining that the material aspect of the world is composed of the same elements as mind, but in a different order [fr
Heisenberg rise of total cross sections
International Nuclear Information System (INIS)
Ezhela, V.V.; Yushchenko, O.P.
1988-01-01
It is shown that on the basis of the original idea of Heisenberg on the quasiclassical picture of extended particle interactions one can construct a satisfactory description of the total cross sections, elastic cross sections, elastic diffractive slopes and mean charged multiplicities in the cm energy range from 5 to 900 GeV, and produce reasonable extrapolations up to several tens of TeV. 14 refs.; 7 figs.; 2 tabs
Entanglement in a Dimerized Antiferromagnetic Heisenberg Chain
Hao, Xiang; Zhu, Shiqun
2008-01-01
The entanglement properties in an antiferromagnetic dimerized Heisenberg spin-1/2 chain are investigated. The entanglement gap, which is the difference between the ground-state energy and the minimal energy that any separable state can attain, is calculated to detect the entanglement. It is found that the entanglement gap can be increased by varying the alternation parameter. Through thermal energy, the witness of the entanglement can determine a characteristic temperature below that an entan...
International Nuclear Information System (INIS)
Peng Xinhua; Du Jiangfeng; Suter, D.
2005-01-01
Full text: Quantum information processing requires the effective measurement of quantum states. An important method, called quantum state tomography, needs measuring a complete set of observables on the measured system to determine its unknown quantum state ρ. The measurement involves certain noncommuting observables as a result of Bohr's complementarity. Very recently, Allahverdyan et al. proposed a new method in which the unknown quantum state r is determined by measuring a set of commuting observables in the price of a controlled interaction with an auxiliary system. If both systems S and A are spins, their z components (σ z ) can be chosen to measure after some specific Heisenberg exchange interaction. We study in detail a general Heisenberg XYZ model for a two-qubit system and present two classes of special Heisenberg interactions which can serve as the controlled interaction in Allahverdyan's scheme when the state of the auxiliary system A is initially completely disordered. Using the nuclear magnetic resonance techniques, the measurement scheme in a single apparatus has been experimentally demonstrated by designing the quantum circuit to simulate the Heisenberg exchange interaction. (author)
International Nuclear Information System (INIS)
Korshunov, S.E.; Uimin, G.V.
1986-01-01
A most popular model in the family of two-dimensional uniformly-frustrated XY models is the antiferromagnetic model on a triangular lattice (AF XY(t) model). Its ground state is both continuously and twofold discretely degenerated. Different phase transitions possible in such systems are investigated. Relevant topological excitations are analyzed and a new class of such (vortices with a fractional number of circulation quanta) is discovered. Their role in determining the properties of the system proves itself essential. The characteristics of phase transitions related to breaking of discrete and continuous symmetries change. The phase diagram of the ''generalized'' AF XY(t) model is constructed. The results obtained are rederived in the representation of the Coulomb gas with half-interger charges, equivalent to the AF XY(t) model with the Berezinskii-Villain interaction
Phase diagram and quench dynamics of the cluster-XY spin chain.
Montes, Sebastián; Hamma, Alioscia
2012-08-01
We study the complete phase space and the quench dynamics of an exactly solvable spin chain, the cluster-XY model. In this chain, the cluster term and the XY couplings compete to give a rich phase diagram. The phase diagram is studied by means of the quantum geometric tensor. We study the time evolution of the system after a critical quantum quench using the Loschmidt echo. The structure of the revivals after critical quantum quenches presents a nontrivial behavior depending on the phase of the initial state and the critical point.
Higher-spin cluster algorithms: the Heisenberg spin and U(1) quantum link models
Energy Technology Data Exchange (ETDEWEB)
Chudnovsky, V
2000-03-01
I discuss here how the highly-efficient spin-1/2 cluster algorithm for the Heisenberg antiferromagnet may be extended to higher-dimensional representations; some numerical results are provided. The same extensions can be used for the U(1) flux cluster algorithm, but have not yielded signals of the desired Coulomb phase of the system.
Higher-spin cluster algorithms: the Heisenberg spin and U(1) quantum link models
International Nuclear Information System (INIS)
Chudnovsky, V.
2000-01-01
I discuss here how the highly-efficient spin-1/2 cluster algorithm for the Heisenberg antiferromagnet may be extended to higher-dimensional representations; some numerical results are provided. The same extensions can be used for the U(1) flux cluster algorithm, but have not yielded signals of the desired Coulomb phase of the system
Formation of quadrupolar phase in non-Heisenberg ferromagnets with half-integer spin
International Nuclear Information System (INIS)
Fridman, Yu.A.; Kosmachev, O.A.; Spirin, D.V.
2005-01-01
Possibility of realization of quadrupolar phase in non-Heisenberg ferromagnet with magnetic ion spin 32 is studied. It is shown that such phase state exists only in ferromagnets with high value of biquadratic exchange when external magnetic field is not applied. Phase diagram of the system is built
Criticality of the D=2 anisotropic quantum Heisenberg model
International Nuclear Information System (INIS)
Caride, A.O.; Tsallis, C.; Zanette, S.I.
1983-01-01
Within a real space renormalization group framework, the square-lattice spin-1/2 Heisenberg ferromagnet in the presence of an Ising-like anisotropy is discussed. The controversial point on how T sub(c) vanishes in the isotropic Heisenberg limit is analyzed: quite strong evidence is presented favoring a continuous function of anisotropy. The crossover from the isotropic Heisenberg model to the pure Ising one is exhibited. (Author) [pt
Barrier functions for Pucci-Heisenberg operators and applications
Cutri , Alessandra; Tchou , Nicoletta
2007-01-01
International audience; The aim of this article is the explicit construction of some barrier functions ("fundamental solutions") for the Pucci-Heisenberg operators. Using these functions we obtain the continuity property, up to the boundary, for the viscosity solution of fully non-linear Dirichlet problems on the Heisenberg group, if the boundary of the domain satisfies some regularity geometrical assumptions (e.g. an exterior Heisenberg-ball condition at the characteristic points). We point ...
46,XY hypergonadotropic hypogonadism and myasthenia gravis.
Lichiardopol, Corina; Herlea, V; Ioan, Virginia; Tomulescu, V; Mixich, F
2006-01-01
Both hypergonadotropic hypogonadism and myasthenia gravis can be parts of type II autoimmune polyendocrine syndrome and association between the two disorders has been reported in few cases. A 14 year old male patient with a personal history of bilateral cryptorchidism and ptosis was referred for delayed puberty. Clinical examination revealed eunuchoid habitus, small, soft testes, gynecomastia, ptosis, a myasthenic deficit score of 22.5 points and an IQ of 84 points. Decreased testosterone (0.064 ng/mL) and elevated LH (64.5 mUI/mL) were consistent with hypergonadotropic hypogonadism and karyotype was normal: 46,XY. Thyroid function, haematologic evaluation, BUN, electrolytes, and glycemia were in the normal range. Therapy consisted of anticholinesterase inhibitors, immunosuppressants, corticotherapy, testosterone; thoracoscopic thymectomy was performed showing thymic lymphoid hyperplasia on histopathologic examination. Myasthenic score improved (12.5 points), progressive virilization occurred, and a year later the patient presented with cushingoid features and obesity.
Coulomb-gas scaling, superfluid films, and the XY model
International Nuclear Information System (INIS)
Minnhagen, P.; Nylen, M.
1985-01-01
Coulomb-gas-scaling ideas are invoked as a link between the superfluid density of two-dimensional 4 He films and the XY model; the Coulomb-gas-scaling function epsilon(X) is extracted from experiments and is compared with Monte Carlo simulations of the XY model. The agreement is found to be excellent
Heisenberg and the German atomic project
International Nuclear Information System (INIS)
Hermann, A.
1988-01-01
The discovery of nuclear fusion 50 years ago, man's entry into the new atomic age, occurred in a fateful era, marked by the Munich Agreement shortly before and the outbreak of World War II shortly afterwards. Werner Heisenberg, Germany's Number One Physicist, was, on the one hand, respected as a competent and 'useful' theoretician, but on the other, was reviled as a 'white Jew, the spirit of Einstein's spirit'. He plays a key role in answering the question of whether research at that time could have resulted in a German atomic bomb. (orig.) [de
Heisenberg Model in a Rotating Magnetic Field
Institute of Scientific and Technical Information of China (English)
LIN Qiong-Gui
2005-01-01
We study the Heisenberg model under the influence of a rotating magnetic field. By using a time-dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no chronological product. The spin vectors (mean values of the spin operators) are obtained as explicit functions of time in the most general case. A series of cyclic solutions are presented. The nonadiabatic geometric phases of these cyclic solutions are calculated, and are expressed in terms of the solid angle subtended by the closed trace of the total spin vector, as well as in terms of those of the individual spins.
Quantum phase transitions in random XY spin chains
International Nuclear Information System (INIS)
Bunder, J.E.; McKenzie, R.H.
2000-01-01
Full text: The XY spin chain in a transverse field is one of the simplest quantum spin models. It is a reasonable model for heavy fermion materials such as CeCu 6-x Au x . It has two quantum phase transitions: the Ising transition and the anisotropic transition. Quantum phase transitions occur at zero temperature. We are investigating what effect the introduction of randomness has on these quantum phase transitions. Disordered systems which undergo quantum phase transitions can exhibit new universality classes. The universality class of a phase transition is defined by the set of critical exponents. In a random system with quantum phase transitions we can observe Griffiths-McCoy singularities. Such singularities are observed in regions which have no long range order, so they are not classified as critical regions, yet they display phenomena normally associated with critical points, such as a diverging susceptibility. Griffiths-McCoy phases are due to rare regions with stronger than! average interactions and may be present far from the quantum critical point. We show how the random XY spin chain may be mapped onto a random Dirac equation. This allows us to calculate the density of states without making any approximations. From the density of states we can describe the conditions which should allow a Griffiths-McCoy phase. We find that for the Ising transition the dynamic critical exponent, z, is not universal. It is proportional to the disorder strength and inversely proportional to the energy gap, hence z becomes infinite at the critical point where the energy gap vanishes
Anti-ferromagnetic Heisenberg model on bilayer honeycomb
International Nuclear Information System (INIS)
Shoja, M.; Shahbazi, F.
2012-01-01
Recent experiment on spin-3/2 bilayer honeycomb lattice antiferromagnet Bi 3 Mn 4 O 12 (NO 3 ) shows a spin liquid behavior down to very low temperatures. This behavior can be ascribed to the frustration effect due to competitions between first and second nearest neighbour's antiferromagnet interaction. Motivated by the experiment, we study J 1 -J 2 Antiferromagnet Heisenberg model, using Mean field Theory. This calculation shows highly degenerate ground state. We also calculate the effect of second nearest neighbor through z direction and show these neighbors also increase frustration in these systems. Because of these degenerate ground state in these systems, spins can't find any ground state to be freeze in low temperatures. This behavior shows a novel spin liquid state down to very low temperatures.
Comments on 'On a proposed new test of Heisenberg's principle'
International Nuclear Information System (INIS)
Home, D.; Sengupta, S.
1981-01-01
A logical fallacy is pointed out in Robinson's analysis (J. Phys. A.; 13:877 (1980)) of a thought experiment purporting to show violation of Heisenberg's uncertainty principle. The real problem concerning the interpretation of Heisenberg's principle is precisely stated. (author)
Extended Heisenberg principle: Tentative analysis of its applications
International Nuclear Information System (INIS)
Golbbiewski, A.; Witko, M.
1988-01-01
The paper examines the extension of the Heisenberg principle for a larger number of simultaneously discussed observables. The possibilities of the extended Heisenberg principle are discussed for evaluation of the average value of the square of the selected operator and for evaluation of the standard deviation of the selected operator
Werner Heisenberg, 5 December 1901 - 1 February 1976
International Nuclear Information System (INIS)
Mott, N.; Peierls, R.
1977-01-01
An account is given of the life and work of Werner Heisenberg, with particular reference to his contribution to quantum mechanics and the formulation of the uncertainty principle. The development of atomic energy in Germany during the war is described, and the part played by Heisenberg in German post-war science. (U.K.)
Science 101: What, Exactly, Is the Heisenberg Uncertainty Principle?
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…
Figueiredo, T. P.; Rocha, J. C. S.; Costa, B. V.
2017-12-01
Although the topological Berezinskii-Kosterlitz-Thouless transition was for the first time described by 40 years ago, it is still a matter of discussion. It has been used to explain several experiments in the most diverse physical systems. In contrast with the ordinary continuous phase transitions the BKT-transition does not break any symmetry. However, in some contexts it can easily be confused with other continuous transitions, in general due to an insufficient data analysis. The two-dimensional XY (or sometimes called planar rotator) spin model is the fruit fly model describing the BKT transition. As demonstrated by Bramwell and Holdsworth (1993) the finite-size effects are more important in two-dimensions than in others due to the logarithmic system size dependence of the properties of the system. Closely related is the anisotropic two dimensional Heisenberg model (AH). Although they have the same Hamiltonian the spin variable in the former has only two degrees of freedom while the AH has three. Many works treat the AH model as undergoing a transition in the same universality class as the XY model. However, its characterization as being in the BKT class of universality deserve some investigation. This paper has two goals. First, we describe an analytical evidence showing that the AH model is in the BKT class of universality. Second, we make an extensive simulation, using the numerical Replica Exchange Wang-Landau method that corroborate our analytical calculations. From our simulation we obtain the BKT transition temperature as TBKT = 0 . 6980(10) by monitoring the susceptibility, the two point correlation function and the helicity modulus. We discuss the misuse of the fourth order Binder's cumulant to locate the transition temperature. The specific heat is shown to have a non-critical behavior as expected in the BKT transition. An analysis of the two point correlation function at low temperature, C(r) ∝r - η(T), shows that the exponent, η, is consistent
Directory of Open Access Journals (Sweden)
Rafael Fabiano Machado Rosa
2008-11-01
ser rotineiramente avaliados em indivíduos com amenorréia primária. Dessa forma, haveria um reconhecimento mais precoce das pacientes 46,XY e, conseqüentemente, um adequado manejo clínico das mesmas.PURPOSE: to verify the prevalence and clinical characteristics of patients with primary amenorrhea and XY caryotype, evaluated in our Service, aiming at identifying findings which could help their recognition. METHODS: from January 1975 to November 2007, 104 patients with amenorrhea were evaluated. All the cases were analyzed by the caryotype by GTG bands. Among them, 21 (20.2% presented a XY 46 constitution. Nevertheless, two of them were excluded from the study, because of incomplete data in their patient's chart. Most of the 19 patients who formed the sample had been referred to us by the gynecology clinics (63.2%. Their ages varied from 16 to 41 years old (an average of 22.1. Data were collected about their family and previous history, physical examination and results of complementary exams and the information was taken into consideration to determine the diagnosis. RESULTS: the predominant diagnosis was resistance to androgens syndrome (n=12; 63.2%; five patients (25.3% presented XY pure gonadal dysgenesis (XY PGD, one (5.3% 17 alpha-hydroxylase deficiency, and one (5.3%, 5 alpha-reductase deficiency. Clinical findings frequently found in these patients included abnormal development of secondary sexual characters (n=19, uterine agenesia with a blind vagina (n=14, family history of amenorrhea (n=8, and palpable gonads in the inguinal canal (n=5. Two of them presented a history of inguinal hernia. Systemic arterial hypertension was only diagnosed in the patient with 17 alpha-hydroxylase deficiency, and gonadal malignization, in the one with XY PGD. CONCLUSIONS: the rate of patients with XY caryotype (20% was higher than the one described in the literature (3 to 11%. It is believed that this fact is related to the way patients are usually referred to our service
Unceratainty of Heisenberg in Universe Destruction
Directory of Open Access Journals (Sweden)
Sri Jumini
2017-12-01
Full Text Available The Qur'an is a guidence which explaines all about the universe to human being. The discovery of science has been able to explain the truth of the Qur'an scientifically. One of which is the principle of Heisenberg's uncertainty in the event of the universe destruction. The purpose of this research is to know: 1 Science's view of the event of the universe destruction (Big Crunch in Qur’an [Al Infithaar]: 1-3, and How the relation of Heisenberg’s uncertainty principles and the law of thermodynamics II toward the collapse of the universe (Big Crunch based on Scientific views and the Quran. This research is a qualitative research using library research method which analyzes the related books directly or indirectly. The results of the analysis stated that: 1 The concentration of mass, which is big enough, relates to some of the laws of physics, those are: Relativity, Heisenberg's uncertainty principles, and the law of Thermodynamic II; 2 The universe will return at its sole point, i.e; the absence of the universe; 3 The destruction of the universe is the destruction of the order of the universe which then the stars fall scatteredly because of the gravitational force that prevents them disappears, the balance of the universe diminishes, decreases and becomes uncertain, and eventually disappears.
About the unitary discretizations of Heisenberg equations of motion
International Nuclear Information System (INIS)
Vazquez, L.
1986-01-01
In a recent paper Bender et al. (1985) have used a unitary discretization of Heisenberg equations for a one-dimensional quantum system in order to obtain information about the spectrum of the underlying continuum theory. The method consists in comparing the matrix elements between adjacent Fock states of the operators and at two steps. At the same time a very simple variational approach must be made. The purpose of this paper is to show that with unitary schemes, accurate either to order τ or τ 2 , we obtain the same spectrum results in the framework of the above method. On the other hand the same eigenvalues are obtained with a non-unitary scheme (Section II). In Section III we discuss the construction of the Hamiltonian associated to the unitary discretizations. (orig.)
Variational principles for particles and fields in Heisenberg matrix mechanics
International Nuclear Information System (INIS)
Klein, A.; Li, C.T.; Vassanji, M.
1980-01-01
For many years we have advocated a form of quantum mechanics based on the application of sum rule methods (completeness) to the equations of motion and to the commutation relations, i.e., to Heisenberg matrix mechanics. Sporadically we have discussed or alluded to a variational foundation for this method. In this paper we present a series of variational principles applicable to a range of systems from one-dimensional quantum mechanics to quantum fields. The common thread is that the stationary quantity is the trace of the Hamiltonian over Hilbert space (or over a subspace of interest in an approximation) expressed as a functional of matrix elements of the elementary operators of the theory. These parameters are constrained by the kinematical relations of the theory introduced by the method of Lagrange multipliers. For the field theories, variational principles in which matrix elements of the density operators are chosen as fundamental are also developed. A qualitative discussion of applications is presented
International Nuclear Information System (INIS)
Alécio, Raphael C.; Lyra, Marcelo L.; Strečka, Jozef
2016-01-01
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. - Highlights: • Ground-state properties of Ising-Heisenberg and full Heisenberg spin tubes are studied. • Phases with 1/3 and 2/3 magnetization plateaus are present in both models. • We unveil the region in the parameter space on which inter-rung quantum fluctuations are relevant. • The full Heisenberg tube exhibits quantum bipartite entanglement between intra- as well as inter-rung spins.
Achieving the Heisenberg limit in quantum metrology using quantum error correction.
Zhou, Sisi; Zhang, Mengzhen; Preskill, John; Jiang, Liang
2018-01-08
Quantum metrology has many important applications in science and technology, ranging from frequency spectroscopy to gravitational wave detection. Quantum mechanics imposes a fundamental limit on measurement precision, called the Heisenberg limit, which can be achieved for noiseless quantum systems, but is not achievable in general for systems subject to noise. Here we study how measurement precision can be enhanced through quantum error correction, a general method for protecting a quantum system from the damaging effects of noise. We find a necessary and sufficient condition for achieving the Heisenberg limit using quantum probes subject to Markovian noise, assuming that noiseless ancilla systems are available, and that fast, accurate quantum processing can be performed. When the sufficient condition is satisfied, a quantum error-correcting code can be constructed that suppresses the noise without obscuring the signal; the optimal code, achieving the best possible precision, can be found by solving a semidefinite program.
Energy Technology Data Exchange (ETDEWEB)
Masood, Syed [Department of Physics, International Islamic University, H-10 Sector, Islamabad (Pakistan); Faizal, Mir, E-mail: mirfaizalmir@gmail.com [Irving K. Barber School of Arts and Sciences, University of British Columbia – Okanagan, Kelowna, BC V1V 1V7 (Canada); Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada); Zaz, Zaid [Department of Electronics and Communication Engineering, University of Kashmir, Srinagar, Kashmir, 190006 (India); Ali, Ahmed Farag [Department of Physics, Faculty of Science, Benha University, Benha, 13518 (Egypt); Raza, Jamil [Department of Physics, International Islamic University, H-10 Sector, Islamabad (Pakistan); Shah, Mushtaq B. [Department of Physics, National Institute of Technology, Srinagar, Kashmir, 190006 (India)
2016-12-10
In this paper, we will propose the most general form of the deformation of Heisenberg algebra motivated by the generalized uncertainty principle. This deformation of the Heisenberg algebra will deform all quantum mechanical systems. The form of the generalized uncertainty principle used to motivate these results will be motivated by the space fractional quantum mechanics, and non-locality in quantum mechanical systems. We also analyse a specific limit of this generalized deformation for one dimensional system, and in that limit, a nonlocal deformation of the momentum operator generates a local deformation of all one dimensional quantum mechanical systems. We analyse the low energy effects of this deformation on a harmonic oscillator, Landau levels, Lamb shift, and potential barrier. We also demonstrate that this deformation leads to a discretization of space.
International Nuclear Information System (INIS)
Masood, Syed; Faizal, Mir; Zaz, Zaid; Ali, Ahmed Farag; Raza, Jamil; Shah, Mushtaq B.
2016-01-01
In this paper, we will propose the most general form of the deformation of Heisenberg algebra motivated by the generalized uncertainty principle. This deformation of the Heisenberg algebra will deform all quantum mechanical systems. The form of the generalized uncertainty principle used to motivate these results will be motivated by the space fractional quantum mechanics, and non-locality in quantum mechanical systems. We also analyse a specific limit of this generalized deformation for one dimensional system, and in that limit, a nonlocal deformation of the momentum operator generates a local deformation of all one dimensional quantum mechanical systems. We analyse the low energy effects of this deformation on a harmonic oscillator, Landau levels, Lamb shift, and potential barrier. We also demonstrate that this deformation leads to a discretization of space.
Field dependent spin transport of anisotropic Heisenberg chain
Energy Technology Data Exchange (ETDEWEB)
Rezania, H., E-mail: rezania.hamed@gmail.com
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. - Highlights: • Theoretical calculation of spin conductivity of spin chain Heisenberg model. • The investigation of the effects of anisotropy and magnetic field on the temperature dependence of spin conductivity. • The study of the effect of temperature on the spin Drude weight.
International Nuclear Information System (INIS)
Fridman, Yu.A.; Klevets, Ph.N.; Kozhemyako, O.V.
2003-01-01
Influence of magnetoelastic (ME) interaction on the phase transitions in two-dimensional non-Heisenberg ferromagnets is investigated. It is shown that if the constant of Heisenberg exchange interaction is large, the ferromagnetic phase is implemented in a system. When the value of biquadratic exchange interaction increases there is a phase transition to the quadrupolar phase characterized by the tensor order parameters. Thus, ME interaction plays an essential role, not only stabilizing the long-range magnetic order in the system, but also determining the order of the phase transition
Multipartite geometric entanglement in finite size XY model
Energy Technology Data Exchange (ETDEWEB)
Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Giampaolo, Salvatore Marco; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)
2009-06-01
We investigate the behavior of the multipartite entanglement in the finite size XY model by means of the hierarchical geometric measure of entanglement. By selecting specific components of the hierarchy, we study both global entanglement and genuinely multipartite entanglement.
Structure factors for the alternating Heisenberg chain
International Nuclear Information System (INIS)
Hamer, C.J.; Zheng, W.
2004-01-01
Full text: We develop a linked cluster method to calculate the spectral weights of many-particle excitations at zero temperature. The dynamical structure factor, which is measured in neutron scattering experiments, is expressed as a sum of 'exclusive' structure factors, each representing the contribution of a specific excited state. We apply these methods to the alternating Heisenberg chain, where complete wave-vector and frequency dependent spectral weights for one- and two-particle excitations (continuum and bound states) are calculated near the dimerized limit (λ = O). We also examine the variation of the spectral weights as the uniform chain (λ = 1) is approached. In agreement with Schmidt and Uhrig, we find that the spectral weight is dominated by 2-triplet states, even at λ 1, which implies that a description in terms of triplet-pair excitations remains a good quantitative description even for the uniform, undimerized chain
Dynamical properties of dissipative XYZ Heisenberg lattices
Rota, R.; Minganti, F.; Biella, A.; Ciuti, C.
2018-04-01
We study dynamical properties of dissipative XYZ Heisenberg lattices where anisotropic spin-spin coupling competes with local incoherent spin flip processes. In particular, we explore a region of the parameter space where dissipative magnetic phase transitions for the steady state have been recently predicted by mean-field theories and exact numerical methods. We investigate the asymptotic decay rate towards the steady state both in 1D (up to the thermodynamical limit) and in finite-size 2D lattices, showing that critical dynamics does not occur in 1D, but it can emerge in 2D. We also analyze the behavior of individual homodyne quantum trajectories, which reveal the nature of the transition.
Quantum stability for the Heisenberg ferromagnet
International Nuclear Information System (INIS)
Bargheer, Till; Beisert, Niklas; Gromov, Nikolay
2008-01-01
Highly spinning classical strings on RxS 3 are described by the Landau-Lifshitz model or equivalently by the Heisenberg ferromagnet in the thermodynamic limit. The spectrum of this model can be given in terms of spectral curves. However, it is a priori not clear whether any given admissible spectral curve can actually be realized as a solution to the discrete Bethe equations, a property which can be referred to as stability. In order to study the issue of stability, we find and explore the general two-cut solution or elliptic curve. It turns out that the moduli space of this elliptic curve shows a surprisingly rich structure. We present the various cases with illustrations and thus gain some insight into the features of multi-cut solutions. It appears that all admissible spectral curves are indeed stable if the branch cuts are positioned in a suitable, non-trivial fashion.
Heisenberg vortex for light-weight refrigeration of liquid hydrogen
National Aeronautics and Space Administration — Only 83 years ago Werner Karl Heisenberg was awarded the Nobel Prize in physics. His work led to the creation of quantum mechanics, the application of which has,...
Heisenberg's principle of uncertainty and the uncertainty relations
International Nuclear Information System (INIS)
Redei, Miklos
1987-01-01
The usual verbal form of the Heisenberg uncertainty principle and the usual mathematical formulation (the so-called uncertainty theorem) are not equivalent. The meaning of the concept 'uncertainty' is not unambiguous and different interpretations are used in the literature. Recently a renewed interest has appeared to reinterpret and reformulate the precise meaning of Heisenberg's principle and to find adequate mathematical form. The suggested new theorems are surveyed and critically analyzed. (D.Gy.) 20 refs
Linear-Optical Generation of Eigenstates of the Two-Site XY Model
Directory of Open Access Journals (Sweden)
Stefanie Barz
2015-04-01
Full Text Available Much of the anticipation accompanying the development of a quantum computer relates to its application to simulating dynamics of another quantum system of interest. Here, we study the building blocks for simulating quantum spin systems with linear optics. We experimentally generate the eigenstates of the XY Hamiltonian under an external magnetic field. The implemented quantum circuit consists of two cnot gates, which are realized experimentally by harnessing entanglement from a photon source and applying a cphase gate. We tune the ratio of coupling constants and the magnetic field by changing local parameters. This implementation of the XY model using linear quantum optics might open the door to future studies of quenching dynamics using linear optics.
Quantum Dense Coding About a Two-Qubit Heisenberg XYZ Model
Xu, Hui-Yun; Yang, Guo-Hui
2017-09-01
By taking into account the nonuniform magnetic field, the quantum dense coding with thermal entangled states of a two-qubit anisotropic Heisenberg XYZ chain are investigated in detail. We mainly show the different properties about the dense coding capacity ( χ) with the changes of different parameters. It is found that dense coding capacity χ can be enhanced by decreasing the magnetic field B, the degree of inhomogeneity b and temperature T, or increasing the coupling constant along z-axis J z . In addition, we also find χ remains the stable value as the change of the anisotropy of the XY plane Δ in a certain temperature condition. Through studying different parameters effect on χ, it presents that we can properly turn the values of B, b, J z , Δ or adjust the temperature T to obtain a valid dense coding capacity ( χ satisfies χ > 1). Moreover, the temperature plays a key role in adjusting the value of dense coding capacity χ. The valid dense coding capacity could be always obtained in the lower temperature-limit case.
Spin nematic and orthogonal nematic states in S=1 non-Heisenberg magnet
International Nuclear Information System (INIS)
Fridman, Yu.A.; Kosmachev, O.A.; Klevets, Ph.N.
2013-01-01
Phases of S=1 non-Heisenberg magnet at various relationships between the exchange integrals are studied in the mean-field limit at zero temperature. It is shown that four phases can be realized in the system under consideration: the ferromagnetic, antiferromagnetic, nematic, and the orthogonal nematic states. The phase diagram is constructed. It is shown that the phase transitions between the ferromagnetic phase and the orthogonal nematic phase and between the antiferromagnetic phase and the orthogonal nematic phase are the degenerated first-order transitions. For the first time the spectra of elementary excitations in all phases are obtained within the mean-field limit. - Highlights: ► We investigated phases of S=1 non-Heisenberg magnet. ► Found four phases: ferromagnetic, antiferromagnetic, nematic, and orthogonal nematic. ► The phase diagram is determined. ► The spectra of elementary excitations are obtained in all phases for the first time.
Three types magnetic moment distribution of nonlinear excitations in a Heisenberg helimagnet
Energy Technology Data Exchange (ETDEWEB)
Qi, Jian-Wen [School of Physics, Northwest University, Xi' an 710069 (China); Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi' an 710069 (China); Li, Zai-Dong [Department of Applied Physics, Hebei University of Technology, Tianjin 300401 (China); Yang, Zhan-Ying, E-mail: zyyang@nwu.edu.cn [School of Physics, Northwest University, Xi' an 710069 (China); Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi' an 710069 (China); Yang, Wen-Li [Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi' an 710069 (China); Institute of Modern Physics, Northwest University, Xi' an 710069 (China)
2017-06-15
Highlights: • Three different types of soliton excitations under the spin-wave background are demonstrated in spin chain system. • The magnetic moment distributions corresponding to these solitons are characterized in detail. • The formation mechanisms of those excitations are explained by the magnon density distribution. - Abstract: We study the nonlinear spin dynamics of an anisotropic Heisenberg helimagnet in a fourth-order integrable nonlinear Schrödinger equation. We demonstrate that there are three types of nonlinear spin excitations on a spin-wave background in the Heisenberg helimagnet, notably including anti-dark soliton, W-shaped soliton, and multi-peak soliton. The magnetic moment distribution that corresponds to each of these are characterized in detail. Additionally, the formation mechanism is clarified by the magnon density distribution.
A simple and powerful XY-Type current monitor for 30 MeV IPEN/CNEN-SP cyclotron
Energy Technology Data Exchange (ETDEWEB)
Barcellos, Henrique; Matsuda, Hylton; Sumyia, Luiz Carlos do A.; Junqueira, Fernando de C.; Costa, Osvaldo L. da, E-mail: hbolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2017-11-01
A water-cooled XY-type current monitor was designed and built in the Cyclotrons Laboratory of the Nuclear and Energy Research Institute (IPEN). It is a very simple design and easily adaptable to the cyclotron beam lines. Tests were done demonstrating to be an instrument of great assistance in proton beam position along beam transport line and target port. Nowadays the XY-type current monitor has been widely used in {sup 18}F-FDG routine productions, employing irradiation system which were originally designed for productions on 18 MeV cyclotron accelerator only, however, applying the XY-type current monitor the target port may be exchanged between the 30 MeV and 18 MeV cyclotrons and the observed results are in perfect agreement with expected. (author)
Quantum critical singularities in two-dimensional metallic XY ferromagnets
Varma, Chandra M.; Gannon, W. J.; Aronson, M. C.; Rodriguez-Rivera, J. A.; Qiu, Y.
2018-02-01
An important problem in contemporary physics concerns quantum-critical fluctuations in metals. A scaling function for the momentum, frequency, temperature, and magnetic field dependence of the correlation function near a 2D-ferromagnetic quantum-critical point (QCP) is constructed, and its singularities are determined by comparing to the recent calculations of the correlation functions of the dissipative quantum XY model (DQXY). The calculations are motivated by the measured properties of the metallic compound YFe2Al10 , which is a realization of the DQXY model in 2D. The frequency, temperature, and magnetic field dependence of the scaling function as well as the singularities measured in the experiments are given by the theory without adjustable exponents. The same model is applicable to the superconductor-insulator transitions, classes of metallic AFM-QCPs, and as fluctuations of the loop-current ordered state in hole-doped cuprates. The results presented here lend credence to the solution found for the 2D-DQXY model and its applications in understanding quantum-critical properties of diverse systems.
Graphics of (X,Y) spectrum for microcomputer
International Nuclear Information System (INIS)
Macias B, L.R.
1991-08-01
When carrying out diffraction works is frequently required to visualize the spectra of the data obtained in order to analyzing them. The design for the obtaining of data in the neutron diffractometer by means of the microcomputer allows to store them in a file by means of the one which transferring to the CYBER system so that by means of its utilities the mentioned spectrum is observed in a graph. In diffraction works, it is sought to study crystalline materials by means of the execution of the Bragg law by that the mounted sample on the diffractometer is subjected to a scanning of the sample with a radiation of a well-known wavelength and this way varying the angles, the corresponding interplanar distances are determined. The main objective of this work, is starting of a data set generated by the diffractometer, to generate the graph of the corresponding (X,Y) spectra in visual form in the screen of a microcomputer and if it is required, to obtain the graph in printed form by means of the same computer program for microcomputer. (Author)
Random isotropic one-dimensional XY-model
Gonçalves, L. L.; Vieira, A. P.
1998-01-01
The 1D isotropic s = ½XY-model ( N sites), with random exchange interaction in a transverse random field is considered. The random variables satisfy bimodal quenched distributions. The solution is obtained by using the Jordan-Wigner fermionization and a canonical transformation, reducing the problem to diagonalizing an N × N matrix, corresponding to a system of N noninteracting fermions. The calculations are performed numerically for N = 1000, and the field-induced magnetization at T = 0 is obtained by averaging the results for the different samples. For the dilute case, in the uniform field limit, the magnetization exhibits various discontinuities, which are the consequence of the existence of disconnected finite clusters distributed along the chain. Also in this limit, for finite exchange constants J A and J B, as the probability of J A varies from one to zero, the saturation field is seen to vary from Γ A to Γ B, where Γ A(Γ B) is the value of the saturation field for the pure case with exchange constant equal to J A(J B) .
Variational principles and Heisenberg matrix mechanics
International Nuclear Information System (INIS)
Klein, A.; Li, C.-T.
1979-01-01
If in Heisenberg's equations of motion for a problem in quantum mechanics (or quantum field theory) one studies matrix elements in the energy representation and by use of completeness conditions expresses the equations solely in terms of matrix elements of the canonical variables, and if one does likewise with the associated kinematical constraints (commutation relations), one arrives at a formulation - largely unexplored hitherto - which can be exploited for both practical and theoretical development. In this contribution, the above theme is developed within the framework of one-dimensional problems. It is shown how this formulation, both dynamics and kinematics, can be derived from a new variational principle, indeed from an entire class of such principles. A powerful method of diagonalizing the Hamiltonians by means of computations utilizing these equations is described. The variational method is shown to be particularly useful for the study of the regime of large quantum numbers. The usual WKB approximation is seen to be contained as well as a basis for the study of systematic corrections to it. Further applications in progress are mentioned. (Auth.)
Form factors of the finite quantum XY-chain
International Nuclear Information System (INIS)
Iorgov, Nikolai
2011-01-01
Explicit factorized formulas for the matrix elements (form factors) of the spin operators σ x and σ y between the eigenvectors of the Hamiltonian of the finite quantum periodic XY-chain in a transverse field were derived. The derivation is based on the relations between three models: the model of quantum XY-chain, Ising model on 2D lattice and N = 2 Baxter-Bazhanov-Stroganov τ (2) -model. Due to these relations we transfer the formulas for the form factors of the latter model recently obtained by the use of separation of variables method to the model of quantum XY-chain. Hopefully, the formulas for the form factors will help in analysis of multipoint dynamic correlation functions at a finite temperature. As an example, we re-derive the asymptotics of the two-point correlation function in the disordered phase without the use of the Toeplitz determinants and the Wiener-Hopf factorization method.
International Nuclear Information System (INIS)
Myrheim, J.
1993-06-01
The thesis deals with the application of different methods to the quantization problem for system of identical particles in one and two dimensions. The standard method is the analytic quantization method due to Schroedinger, which leads to the concept of fractional statistics in one and two dimensions. Two-dimensional particles with fractional statistics are well known by the name of anyons. Two alternative quantization methods are shown by the author, the algebraic method of Heisenberg and the Feynman path integral method. The Feynman method is closely related to the Schroedinger method, whereas the Heisenberg and Schroedinger methods may give different results. The relation between the Heisenberg and Schroedinger methods is discussed. The Heisenberg method is applied to the equations of motion of vortices in superfluid helium, which have the form of Hamiltonian equations for a one-dimensional system. The same method is also discussed more generally for systems of identical particles in one and two dimensions. An application of the Feynman method to the problem of computing the equation of state for a gas of anyons is presented. 104 refs., 4 figs
An RXTE observation of the intermediate polar XY Arietis
International Nuclear Information System (INIS)
Hellier, Coel
1999-01-01
RXTE's observation of XY Ari covered more eclipses of this close binary at a higher count rate than ever before. The eclipses located the accretion regions on the white dwarf and showed that they covered < 0.002 of the white dwarf surface. Additionally we recorded the first outburst of XY Ari seen, allowing us to watch as an unstable accretion disk overwhelmed the magnetic field of the white dwarf and pushed inwards, cutting off our line-of-sight to the lower accretion pole. We also find limits on the mass of the white dwarf
Mutations of the SRY-responsive enhancer of SOX9 are uncommon in XY gonadal dysgenesis.
Georg, I; Bagheri-Fam, S; Knower, K C; Wieacker, P; Scherer, Gerd; Harley, V R
2010-01-01
During mouse sex determination, SRY upregulates the core testis-specific enhancer of Sox9, TESCO. Mutations in human SRY are found in one third of cases with XY pure gonadal dysgenesis (XY GD; Swyer syndrome), while two thirds remain unexplained. Heterozygous SOX9 mutations can cause XY GD in association with the skeletal malformation syndrome campomelic dysplasia. We hypothesized that human TESCO mutations could cause isolated XY GD. Sixty-six XY GD cases with an intact SRY were analyzed for TESCO point mutations or deletions. No mutations were identified. We conclude that TESCO mutations are not a common cause of XY GD. Copyright © 2010 S. Karger AG, Basel.
Heisenberg lecture: Supersymmetry in the spectra of atomic nuclei
International Nuclear Information System (INIS)
Graw, Gerhard
2003-01-01
Talk given at the Symposium: 'Werner Heisenberg und die Wissenschaft, das Denken und die Kunst', Alexander von Humboldt Club, Bucharest, October 16 - 17, 2001, Goethe-Institut, Bucharest, Romania. This Symposium of the Humboldt Club in Bucharest was dedicated to the work of Werner Heisenberg. With the occasion of the hundredth anniversary of his birthday the aim was to recall the impact of Heisenberg's work not only on physics and related fields but also on philosophy and on our present understanding of science. Werner Heisenberg discovered and formulated the laws of quantum physics, the concepts and the tools one uses at present. These discoveries resulted from his ambitious goal to reveal the fundamental laws of physics and to understand these laws within the logical and structural aspects they imply for the understanding of nature and of thinking. In this way he was aware of the potential of this fundamental new approach and applied the concept of quantum phenomena to physics, chemistry, biology, and to logical-philosophical questions. Being invited here as first speaker of this Symposium the author considered as appropriate, first to recall a few dates out of his vita and essentials of his work, and then to address to a timely subject, which is, hopefully, related to the work of Werner Heisenberg. (author)
Effects of surface exchange anisotropy in Heisenberg ferromagnetic insulators
International Nuclear Information System (INIS)
Selzer, S.; Majlis, N.
1982-03-01
We consider an fcc semi-infinite ferromagnetic insulator displaying an anisotropic exchange interaction between spins on the (111) surface plane of the form Jsub(parallel)[Ssub(i)sup(x)Ssub(j)sup(x)+Ssub(i)sup(y)Ssub(j)sup(y )+etaSsub(i)sup(z)Ssub(j)sup(z)], assuming all other interactions isotropic. A self-consistent RPA calculation is performed, with a Green function method valid for any spin S, up to the bulk transition temperature Tsub(c)sup(b), by imposing that the magnetization of the third layer equals the bulk value. For eta sufficiently large, the surface magnetization is non-zero for T>Tsub(c)sup(b), up to a transition temperature Tsub(c)sup(s)(eta) whenever eta>=etasub(c)>1, where Tsub(c)sup(s)(etasub(c))=Tsub(c)sup(b). For T>Tsub(c)sup(b) the system is equivalent to a film of three layers, where the magnetization of the third one is identically zero as a boundary condition. A discontinuity of the derivative in the curve of the magnetization of the first two layers vs. temperature is found at Tsub(c)sup(b). The results show clearly a cross-over from Heisenberg to Ising behaviour at the surface. (author)
Deformed Heisenberg algebra, fractional spin fields, and supersymmetry without fermions
International Nuclear Information System (INIS)
Plyushchay, M.S.
1996-01-01
Within a group-theoretical approach to the description of (2+1)-dimensional anyons, the minimal covariant set of linear differential equations is constructed for the fractional spin fields with the help of the deformed Heisenberg algebra (DHA), [a - ,a + ]=1+νK, involving the Klein operator K, {K,a ± }=0, K 2 =1. The connection of the minimal set of equations with the earlier proposed open-quote open-quote universal close-quote close-quote vector set of anyon equations is established. On the basis of this algebra, a bosonization of supersymmetric quantum mechanics is carried out. The construction comprises the cases of exact and spontaneously broken N=2 supersymmetry allowing us to realize a Bose endash Fermi transformation and spin-1/2 representation of SU(2) group in terms of one bosonic oscillator. The construction admits an extension to the case of OSp(2 parallel 2) supersymmetry, and, as a consequence, both applications of the DHA turn out to be related. The possibility of open-quote open-quote superimposing close-quote close-quote the two applications of the DHA for constructing a supersymmetric (2+1)-dimensional anyon system is discussed. As a consequential result we point out that the osp(2 parallel 2) superalgebra is realizable as an operator algebra for a quantum mechanical 2-body (nonsupersymmetric) Calogero model. Copyright copyright 1996 Academic Press, Inc
Momentum conservation decides Heisenberg's interpretation of the uncertainty formulas
International Nuclear Information System (INIS)
Angelidis, T.D.
1977-01-01
In the light of Heisenberg's interpretation of the uncertainty formulas, the conditions necessary for the derivation of the quantitative statement or law of momentum conservation are considered. The result of such considerations is a contradiction between the formalism of quantum physics and the asserted consequences of Heisenberg's interpretation. This contradiction decides against Heisenberg's interpretation of the uncertainty formulas on upholding that the formalism of quantum physics is both consistent and complete, at least insofar as the statement of momentum conservation can be proved within this formalism. A few comments are also included on Bohr's complementarity interpretation of the formalism of quantum physics. A suggestion, based on a statistical mode of empirical testing of the uncertainty formulas, does not give rise to any such contradiction
Heisenberg's uncertainty relation: Violation and reformulation
International Nuclear Information System (INIS)
Ozawa, Masanao
2014-01-01
The uncertainty relation 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 so that their product should be no less than a limit set by Planck's constant. In 1980, Braginsky, Vorontsov, and Thorne claimed that this relation leads to a sensitivity limit for gravitational wave detectors. However, in 1988 a model of position measurement was constructed that breaks both this limit and Heisenberg's relation. Here, we discuss the problems as to how we reformulate Heisenberg's relation to be universally valid and how we experimentally quantify the error and the disturbance to refute the old relation and to confirm the new relation.
Multi parametric deformed Heisenberg algebras: a route to complexity
International Nuclear Information System (INIS)
Curado, E.M.F.; Rego-Monteiro, M.A.
2000-09-01
We introduce a generalized of the Heisenberg which is written in terms of a functional of one generator of the algebra, f(J 0 ), that can be any analytical function. When f is linear with slope θ, we show that the algebra in this case corresponds to q-oscillators for q 2 = tan θ. The case where f is polynomial of order n in J 0 corresponds to a n-parameter Heisenberg algebra. The representations of the algebra, when f is any analytical function, are shown to be obtained through the study of the stability of the fixed points of f and their composed functions. The case when f is a quadratic polynomial in J 0 , the simplest non-linear scheme which is able to create chaotic behavior, is analyzed in detail and special regions in the parameter space give representations that ca not be continuously deformed to representations of Heisenberg algebra. (author)
Heisenberg in the atomic age science and the public sphere
Carson, Cathryn
2010-01-01
The end of the Second World War opened a new era for science in public life. Heisenberg in the Atomic Age explores the transformations of science's public presence in the postwar Federal Republic of Germany. It shows how Heisenberg's philosophical commentaries, circulating in the mass media, secured his role as science's public philosopher, and it reflects on his policy engagements and public political stands, which helped redefine the relationship between science and the state. With deep archival grounding, the book tracks Heisenberg's interactions with intellectuals from Heidegger to Habermas and political leaders from Adenauer to Brandt. It also traces his evolving statements about his wartime research on nuclear fission for the National Socialist regime. Working between the history of science and German history, the book's central theme is the place of scientific rationality in public life - after the atomic bomb, in the wake of the Third Reich.
Entanglement dynamics of a Heisenberg chain with Dzyaloshinskii–Moriya interaction
International Nuclear Information System (INIS)
Qiang, Zheng; Xiao-Ping, Zhang; Zhong-Zhou, Ren; Qi-Jun, Zhi
2009-01-01
This paper investigates the entanglement dynamics of the system, composed of two qubits A and B with Heisenberg XX spin interactation. There is a third controller qubit C, which only has Dzyaloshinskii–Moriya (DM) spin-orbit interaction with the qubit B. It is found that depending on the initial state of the controller qubit C and DM interaction, the entanglement of the system displays amplification and sudden birth effects. These effects indicate that one can control the entanglement of the system, which may be helpful for quantum information processing. (general)
Teleportation via thermally entangled states of a two-qubit Heisenberg XXZ chain
Institute of Scientific and Technical Information of China (English)
QIN Meng; TAO Ying-Juan; TIAN Dong-Ping
2008-01-01
We investigate quantum teleportation as a tool to study the thermally entangled state of a twoqubit Heisenberg XXZ chain.Our work is mainly to investigate the characteristics of a Heisenberg XXZ chain and get some analytical results of the fully entangled fraction.We also consider the entanglement teleportation via a two-qubit Heisenberg XXZ chain.
On the fermionic Heisenberg group and its Q-representation
International Nuclear Information System (INIS)
Frydryszak, A.
1992-01-01
A nonstandard way of representing the canonical anticommutation relations is presented. It is connected with a generalization of the Heisenberg group to a graded phase space. It is shown how Grassmann harmonic analysis can be performed and what are the Q-representations of such a generalized Heisenberg group. As in the conventional case, the Schroedinger and Bargmann-Fock realizations were shown to exist. Grassmann-Hermite polynomials are obtained via the generalized Bargmann transform and new Grassmann-Laguerre polynomials are introduced. (author). 10 refs
The Finite Heisenberg-Weyl Groups in Radar and Communications
Directory of Open Access Journals (Sweden)
Calderbank AR
2006-01-01
Full Text Available We investigate the theory of the finite Heisenberg-Weyl group in relation to the development of adaptive radar and to the construction of spreading sequences and error-correcting codes in communications. We contend that this group can form the basis for the representation of the radar environment in terms of operators on the space of waveforms. We also demonstrate, following recent developments in the theory of error-correcting codes, that the finite Heisenberg-Weyl groups provide a unified basis for the construction of useful waveforms/sequences for radar, communications, and the theory of error-correcting codes.
Energy Technology Data Exchange (ETDEWEB)
Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.c [Departamento de Fisica y Quimica, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Salazar-Enriquez, C.D.; Londono-Navarro, J.; Jurado, J.F. [Departamento de Fisica y Quimica, Universidad Nacional de Colombia-Sede Manizales, A.A. 127 Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulacion, Instituto de Fisica. Universidad de Antioquia, A.A. 1226, Medellin (Colombia)
2011-06-15
This work presents a critical temperature study of La{sub 1-x}Ca{sub x}MnO{sub 3} manganites in bulk by means of Monte Carlo method thermal activated magnetic properties. The analysis was carried out for stoichiometries in the range of 0{<=}x{<=}1. The model is based on a three-dimensional classical Heisenberg-Hamiltonian involving the presence of Mn{sup 3+eg}, Mn{sup 3+eg'} and Mn{sup 4+} ions, and their nearest neighbor interaction. For this modeling, simple cubic lattice samples of size L{sup 3}, with L=6, 15 and 30 were used. The values of exchange parameters were determined by using LaMnO{sub 3} (x=0), La{sub 0.5}Ca{sub 0.5}MnO{sub 3} and CaMnO{sub 3} (x=1) phases. Relationships between exchange parameters and anisotropy constants for different hole densities were found. Results of transition temperatures for each phase showed good agreement with experimental reports, especially for L=30 and L{yields}{infinity}. - Research highlights: Stoichiometry influences the exchange interaction between magnetic ions. Charge and orbital ordering depend on the stoichiometry. LCMO magnetic phase diagram has a great variety of magnetic states.
Motion of a magnetic soliton about a lattice soliton in a Heisenberg chain
International Nuclear Information System (INIS)
Nayyar, A.H.; Murtaza, G.
1981-08-01
As an example of interaction between two solitons belonging to different species, a semiclassical study of the nonlinear dynamics of a coupled magnon-phonon system in a one-dimensional Heisenberg ferromagnet is made, where both the lattice and the spin systems are taken with their respective nonlinear interactions. The lattice soliton is shown to introduce spatial inhomogeneities into the propagation of the magnetic soliton resulting in (a) the trapping of the magnetic soliton in the harmonic field of the lattice soliton and (b) the amplitude and the width of the magnetic soliton becoming time-dependent. (author)
International Nuclear Information System (INIS)
Curado, E.M.F.; Hassouni, Y.; Rego-Monteiro, M.A.; Rodrigues, Ligia M.C.S.
2008-01-01
We discuss the role of generalized Heisenberg algebras (GHA) in obtaining an algebraic method to describe physical systems. The method consists in finding the GHA associated to a physical system and the relations between its generators and the physical observables. We choose as an example the infinite square-well potential for which we discuss the representations of the corresponding GHA. We suggest a way of constructing a physical realization of the generators of some GHA and apply it to the square-well potential. An expression for the position operator x in terms of the generators of the algebra is given and we compute its matrix elements
Quantum correlations and limit cycles in the driven-dissipative Heisenberg lattice
Owen, E. T.; Jin, J.; Rossini, D.; Fazio, R.; Hartmann, M. J.
2018-04-01
Driven-dissipative quantum many-body systems have attracted increasing interest in recent years as they lead to novel classes of quantum many-body phenomena. In particular, mean-field calculations predict limit cycle phases, slow oscillations instead of stationary states, in the long-time limit for a number of driven-dissipative quantum many-body systems. Using a cluster mean-field and a self-consistent Mori projector approach, we explore the persistence of such limit cycles as short range quantum correlations are taken into account in a driven-dissipative Heisenberg model.
Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas
2011-03-01
A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.
On the continuum limit of a classical compressible Heisenberg chain
International Nuclear Information System (INIS)
Fivez, J.
1982-01-01
The equations of motion are derived for the classical compressible Heisenberg chain in the continuum limit to lowest non-trivial order in the derivatives. It is possible to eliminate the translations from the equation for the spins. The resulting equation does not admit of simple magnetic solitary wave solutions, in contradiction to the results of other authors. (author)
The Bohr-Heisenberg correspondence principle viewed from phase space
DEFF Research Database (Denmark)
Dahl, Jens Peder
2002-01-01
Phase-space representations play an increasingly important role in several branches of physics. Here, we review the author's studies of the Bohr-Heisenberg correspondence principle within the Weyl-Wigner phase-space representation. The analysis leads to refined correspondence rules that can...
On the Clebsch-Gordan series for some Heisenberg groups
International Nuclear Information System (INIS)
Raszillier, H.
1984-11-01
We suggest the use of the Stone-von Neumann theorem for a simple insight into the Clebsch-Gordan series of the Heisenberg groups of quantum mechanics, constructed over the abelian groups Rsup(n) and Fsub(p)sup(n). (orig.)
Finite Heisenberg groups and Seiberg dualities in quiver gauge theories
International Nuclear Information System (INIS)
Burrington, Benjamin A.; Liu, James T.; Mahato, Manavendra; Pando Zayas, Leopoldo A.
2006-01-01
A large class of quiver gauge theories admits the action of finite Heisenberg groups of the form Heis(Z q xZ q ). This Heisenberg group is generated by a manifest Z q shift symmetry acting on the quiver along with a second Z q rephasing (clock) generator acting on the links of the quiver. Under Seiberg duality, however, the action of the shift generator is no longer manifest, as the dualized node has a different structure from before. Nevertheless, we demonstrate that the Z q shift generator acts naturally on the space of all Seiberg dual phases of a given quiver. We then prove that the space of Seiberg dual theories inherits the action of the original finite Heisenberg group, where now the shift generator Z q is a map among fields belonging to different Seiberg phases. As examples, we explicitly consider the action of the Heisenberg group on Seiberg phases for C 3 /Z 3 , Y 4,2 and Y 6,3 quivers
A Poisson type formula for Hardy classes on Heisenberg's group
Directory of Open Access Journals (Sweden)
Lopushansky O.V.
2010-06-01
Full Text Available The Hardy type class of complex functions with infinite many variables defined on the Schrodinger irreducible unitary orbit of reduced Heisenberg group, generated by the Gauss density, is investigated. A Poisson integral type formula for their analytic extensions on an open ball is established. Taylor coefficients for analytic extensions are described by the associatedsymmetric Fock space.
Spin Waves in a Classical Compressible Heisenberg Chain
Fivez, J.; Raedt, H. De
1980-01-01
The effect of the spin—lattice interaction on the spin dynamics of a classical Heisenberg chain is studied by means of a truncated continued fraction. At low temperature, the spin correlation length and the spin wave frequency show the same simple dependence on the coupling.
On the magnetism of Heisenberg double-layer antiferromagnets
International Nuclear Information System (INIS)
Uijen, C.M.J. van.
1980-01-01
The author investigates the sublattice magnetization and the susceptibility of the double-layer Heisenberg antiferromagnet K 3 M 2 F 7 by employing the techniques of elastic and quasi-elastic critical magnetic scattering of neutrons. (G.T.H.)
Low temperature spin wave dynamics in classical Heisenberg chains
International Nuclear Information System (INIS)
Heller, P.; Blume, M.
1977-11-01
A detailed and quantitative study of the low-temperature spin-wave dynamics was made for the classical Heisenberg-coupled chain using computer simulation. Results for the spin-wave damping rates and the renormalization of the spin-wave frequencies are presented and compared with existing predictions
Resolvent kernel for the Kohn Laplacian on Heisenberg groups
Directory of Open Access Journals (Sweden)
Neur Eddine Askour
2002-07-01
Full Text Available We present a formula that relates the Kohn Laplacian on Heisenberg groups and the magnetic Laplacian. Then we obtain the resolvent kernel for the Kohn Laplacian and find its spectral density. We conclude by obtaining the Green kernel for fractional powers of the Kohn Laplacian.
Critical behaviour of magnetic thin film with Heisenberg spin-S model
International Nuclear Information System (INIS)
Masrour, R.; Hamedoun, M.; Bouslykhane, K.; Hourmatallah, A.; Benzakour, N.; Benyoussef, A.
2009-01-01
The magnetic properties of a ferromagnetic thin film of face centered cubic (FCC) lattice with Heisenberg spin-S are examined using the high-temperature series expansions technique extrapolated with Pade approximations method. The critical reduced temperature of the system τ c is studied as function of thickness of the film and the exchange interactions in the bulk, and within the surfaces J b , J s and J perpendicular respectively. A critical value of surface exchange interaction above which surface magnetism appears is obtained. The dependence of the reduced critical temperature on the film thickness L has been investigated.
Cruz, C.
The characterization of quantum information quantifiers has attracted a considerable attention of the scientific community, since they are a useful tool to verify the presence of quantum correlations in a quantum system. In this context, in the present work we show a theoretical study of some quantifiers, such as entanglement witness, entanglement of formation, Bell’s inequality violation and geometric quantum discord as a function of the diffractive properties of neutron scattering. We provide one path toward identifying the presence of quantum correlations and quantum nonlocality in a molecular magnet as a Heisenberg spin-1/2 dimer, by diffractive properties typically obtained via neutron scattering experiments.
Quantum Monte Carlo simulation for S=1 Heisenberg model with uniaxial anisotropy
International Nuclear Information System (INIS)
Tsukamoto, Mitsuaki; Batista, Cristian; Kawashima, Naoki
2007-01-01
We perform quantum Monte Carlo simulations for S=1 Heisenberg model with an uniaxial anisotropy. The system exhibits a phase transition as we vary the anisotropy and a long range order appears at a finite temperature when the exchange interaction J is comparable to the uniaxial anisotropy D. We investigate quantum critical phenomena of this model and obtain the line of the phase transition which approaches a power-law with logarithmic corrections at low temperature. We derive the form of logarithmic corrections analytically and compare it to our simulation results
Large-N behaviour of string solutions in the Heisenberg model
Fujita, T; Takahashi, H
2003-01-01
We investigate the large-N behaviour of the complex solutions for the two-magnon system in the S = 1/2 Heisenberg XXZ model. The Bethe ansatz equations are numerically solved for the string solutions with a new iteration method. Clear evidence of the violation of the string configurations is found at N = 22, 62, 121, 200, 299, 417, but the broken states are still Bethe states. The number of Bethe states is consistent with the exact diagonalization, except for one singular state.
The infinite range Heisenberg model and high temperature superconductivity
Tahir-Kheli, Jamil
1992-01-01
The thesis deals with the theory of high temperature superconductivity from the standpoint of three-band Hubbard models.Chapter 1 of the thesis proposes a strongly coupled variational wavefunction that has the three-spin system of an oxygen hole and its two neighboring copper spins in a doublet and the background Cu spins in an eigenstate of the infinite range antiferromagnet. This wavefunction is expected to be a good "zeroth order" wavefunction in the superconducting regime of dopings. The three-spin polaron is stabilized by the hopping terms rather than the copper-oxygen antiferromagnetic coupling Jpd. Considering the effect of the copper-copper antiferromagnetic coupling Jdd, we show that the three-spin polaron cannot be pure Emery (Dg), but must have a non-negligible amount of doublet-u (Du) character for hopping stabilization. Finally, an estimate is made for the magnitude of the attractive coupling of oxygen holes.Chapter 2 presents an exact solution to a strongly coupled Hamiltonian for the motion of oxygen holes in a 1-D Cu-O lattice. The Hamiltonian separates into two pieces: one for the spin degrees of freedom of the copper and oxygen holes, and the other for the charge degrees of freedom of the oxygen holes. The spinon part becomes the Heisenberg antiferromagnet in 1-D that is soluble by the Bethe Ansatz. The holon piece is also soluble by a Bethe Ansatz with simple algebraic relations for the phase shifts.Finally, we show that the nearest neighbor Cu-Cu spin correlation increases linearly with doping and becomes positive at x [...] 0.70.
Infinite-range Heisenberg model and high-temperature superconductivity
Tahir-Kheli, Jamil; Goddard, William A., III
1993-11-01
A strongly coupled variational wave function, the doublet spin-projected Néel state (DSPN), is proposed for oxygen holes in three-band models of high-temperature superconductors. This wave function has the three-spin system of the oxygen hole plus the two neighboring copper atoms coupled in a spin-1/2 doublet. The copper spins in the neighborhood of a hole are in an eigenstate of the infinite-range Heisenberg antiferromagnet (SPN state). The doublet three-spin magnetic polaron or hopping polaron (HP) is stabilized by the hopping terms tσ and tτ, rather than by the copper-oxygen antiferromagnetic coupling Jpd. Although, the HP has a large projection onto the Emery (Dg) polaron, a non-negligible amount of doublet-u (Du) character is required for optimal hopping stabilization. This is due to Jdd, the copper-copper antiferromagnetic coupling. For the copper spins near an oxygen hole, the copper-copper antiferromagnetic coupling can be considered to be almost infinite ranged, since the copper-spin-correlation length in the superconducting phase (0.06-0.25 holes per in-plane copper) is approximately equal to the mean separation of the holes (between 2 and 4 lattice spacings). The general DSPN wave function is constructed for the motion of a single quasiparticle in an antiferromagnetic background. The SPN state allows simple calculations of various couplings of the oxygen hole with the copper spins. The energy minimum is found at symmetry (π/2,π/2) and the bandwidth scales with Jdd. These results are in agreement with exact computations on a lattice. The coupling of the quasiparticles leads to an attraction of holes and its magnitude is estimated.
Search for the Heisenberg spin glass on rewired square lattices with antiferromagnetic interaction
Energy Technology Data Exchange (ETDEWEB)
Surungan, Tasrief, E-mail: tasrief@unhas.ac.id; Bansawang, B.J.; Tahir, Dahlang [Department of Physics, Hasanuddin University, Makassar, South Sulawesi 90245 (Indonesia)
2016-03-11
Spin glass (SG) is a typical magnetic system with frozen random spin orientation at low temperatures. The system exhibits rich physical properties, such as infinite number of ground states, memory effect, and aging phenomena. There are two main ingredients considered to be pivotal for the existence of SG behavior, namely, frustration and randomness. For the canonical SG system, frustration is led by the presence of competing interaction between ferromagnetic (FM) and antiferromagnetic (AF) couplings. Previously, Bartolozzi et al. [Phys. Rev. B73, 224419 (2006)], reported the SG properties of the AF Ising spins on scale free network (SFN). It is a new type of SG, different from the canonical one which requires the presence of both FM and AF couplings. In this new system, frustration is purely caused by the topological factor and its randomness is related to the irregular connectvity. Recently, Surungan et. al. [Journal of Physics: Conference Series, 640, 012001 (2015)] reported SG bahavior of AF Heisenberg model on SFN. We further investigate this type of system by studying an AF Heisenberg model on rewired square lattices. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter to search for the existence of SG phase.
Spin glass behavior of the antiferromagnetic Heisenberg model on scale free network
International Nuclear Information System (INIS)
Surungan, Tasrief; Zen, Freddy P; Williams, Anthony G
2015-01-01
Randomness and frustration are considered to be the key ingredients for the existence of spin glass (SG) phase. In a canonical system, these ingredients are realized by the random mixture of ferromagnetic (FM) and antiferromagnetic (AF) couplings. The study by Bartolozzi et al. [Phys. Rev. B73, 224419 (2006)] who observed the presence of SG phase on the AF Ising model on scale free network (SFN) is stimulating. It is a new type of SG system where randomness and frustration are not caused by the presence of FM and AF couplings. To further elaborate this type of system, here we study Heisenberg model on AF SFN and search for the SG phase. The canonical SG Heisenberg model is not observed in d-dimensional regular lattices for (d ≤ 3). We can make an analogy for the connectivity density (m) of SFN with the dimensionality of the regular lattice. It should be plausible to find the critical value of m for the existence of SG behaviour, analogous to the lower critical dimension (d l ) for the canonical SG systems. Here we study system with m = 2, 3, 4 and 5. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter. We observed SG phase for each value of m and estimated its corersponding critical temperature. (paper)
Ground state properties of a spin chain within Heisenberg model with a single lacking spin site
International Nuclear Information System (INIS)
Mebrouki, M.
2011-01-01
The ground state and first excited state energies of an antiferromagnetic spin-1/2 chain with and without a single lacking spin site are computed using exact diagonalization method, within the Heisenberg model. In order to keep both parts of a spin chain with a lacking site connected, next nearest neighbors interactions are then introduced. Also, the Density Matrix Renormalization Group (DMRG) method is used, to investigate ground state energies of large system sizes; which permits us to inquire about the effect of large system sizes on energies. Other quantum quantities such as fidelity and correlation functions are also studied and compared in both cases. - Research highlights: → In this paper we compute ground state and first excited state energies of a spin chain with and without a lacking spin site. The next nearest neighbors are introduced with the antiferromagnetic Heisenberg spin-half. → Exact diagonalization is used for small systems, where DMRG method is used to compute energies for large systems. Other quantities like quantum fidelity and correlation are also computed. → Results are presented in figures with comments. → E 0 /N is computed in a function of N for several values of J 2 and for both systems. First excited energies are also investigated.
Search for the Heisenberg spin glass on rewired square lattices with antiferromagnetic interaction
International Nuclear Information System (INIS)
Surungan, Tasrief; Bansawang, B.J.; Tahir, Dahlang
2016-01-01
Spin glass (SG) is a typical magnetic system with frozen random spin orientation at low temperatures. The system exhibits rich physical properties, such as infinite number of ground states, memory effect, and aging phenomena. There are two main ingredients considered to be pivotal for the existence of SG behavior, namely, frustration and randomness. For the canonical SG system, frustration is led by the presence of competing interaction between ferromagnetic (FM) and antiferromagnetic (AF) couplings. Previously, Bartolozzi et al. [Phys. Rev. B73, 224419 (2006)], reported the SG properties of the AF Ising spins on scale free network (SFN). It is a new type of SG, different from the canonical one which requires the presence of both FM and AF couplings. In this new system, frustration is purely caused by the topological factor and its randomness is related to the irregular connectvity. Recently, Surungan et. al. [Journal of Physics: Conference Series, 640, 012001 (2015)] reported SG bahavior of AF Heisenberg model on SFN. We further investigate this type of system by studying an AF Heisenberg model on rewired square lattices. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter to search for the existence of SG phase.
Search for the Heisenberg spin glass on rewired cubic lattices with antiferromagnetic interaction
International Nuclear Information System (INIS)
Surungan, Tasrief
2016-01-01
Spin glass (SG) is a typical magnetic system which is mainly characterized by a frozen random spin orientation at low temperatures. Frustration and randomness are considered to be the key ingredients for the existence of SGs. Previously, Bartolozzi et al . [Phys. Rev. B73, 224419 (2006)] found that the antiferromagnetic (AF) Ising spins on scale free network (SFN) exhibited SG behavior. This is purely AF system, a new type of SG different from the canonical one which requires the presence of both FM and AF couplings. In this new system, frustration is purely due to a topological factor and its randomness is brought by irregular connectivity. Recently, it was reported that the AF Heisenberg model on SFN exhibited SG behavior [Surungan et al ., JPCS, 640, 012005 (2015)/doi:10.1088/1742-6596/640/1/012005]. In order to accommodate the notion of spatial dimension, we further investigated this type of system by studying an AF Heisenberg model on rewired cubic lattices, constructed by adding one extra bond randomly connecting each spin to one of its next-nearest neighbors. We used Replica Exchange algorithm of Monte Carlo Method and calculated the SG order parameter to search for the existence of SG phase. (paper)
Ming, Fei; Wang, Dong; Shi, Wei-Nan; Huang, Ai-Jun; Sun, Wen-Yang; Ye, Liu
2018-04-01
The uncertainty principle is recognized as an elementary ingredient of quantum theory and sets up a significant bound to predict outcome of measurement for a couple of incompatible observables. In this work, we develop dynamical features of quantum memory-assisted entropic uncertainty relations (QMA-EUR) in a two-qubit Heisenberg XXZ spin chain with an inhomogeneous magnetic field. We specifically derive the dynamical evolutions of the entropic uncertainty with respect to the measurement in the Heisenberg XXZ model when spin A is initially correlated with quantum memory B. It has been found that the larger coupling strength J of the ferromagnetism ( J 0 ) chains can effectively degrade the measuring uncertainty. Besides, it turns out that the higher temperature can induce the inflation of the uncertainty because the thermal entanglement becomes relatively weak in this scenario, and there exists a distinct dynamical behavior of the uncertainty when an inhomogeneous magnetic field emerges. With the growing magnetic field | B | , the variation of the entropic uncertainty will be non-monotonic. Meanwhile, we compare several different optimized bounds existing with the initial bound proposed by Berta et al. and consequently conclude Adabi et al.'s result is optimal. Moreover, we also investigate the mixedness of the system of interest, dramatically associated with the uncertainty. Remarkably, we put forward a possible physical interpretation to explain the evolutionary phenomenon of the uncertainty. Finally, we take advantage of a local filtering operation to steer the magnitude of the uncertainty. Therefore, our explorations may shed light on the entropic uncertainty under the Heisenberg XXZ model and hence be of importance to quantum precision measurement over solid state-based quantum information processing.
Nearly Deconfined Spinon Excitations in the Square-Lattice Spin-1/2 Heisenberg Antiferromagnet
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Hui Shao
2017-12-01
Full Text Available We study the spin-excitation spectrum (dynamic structure factor of the spin-1/2 square-lattice Heisenberg antiferromagnet and an extended model (the J-Q model including four-spin interactions Q in addition to the Heisenberg exchange J. Using an improved method for stochastic analytic continuation of imaginary-time correlation functions computed with quantum Monte Carlo simulations, we can treat the sharp (δ-function contribution to the structure factor expected from spin-wave (magnon excitations, in addition to resolving a continuum above the magnon energy. Spectra for the Heisenberg model are in excellent agreement with recent neutron-scattering experiments on Cu(DCOO_{2}·4D_{2}O, where a broad spectral-weight continuum at wave vector q=(π,0 was interpreted as deconfined spinons, i.e., fractional excitations carrying half of the spin of a magnon. Our results at (π,0 show a similar reduction of the magnon weight and a large continuum, while the continuum is much smaller at q=(π/2,π/2 (as also seen experimentally. We further investigate the reasons for the small magnon weight at (π,0 and the nature of the corresponding excitation by studying the evolution of the spectral functions in the J-Q model. Upon turning on the Q interaction, we observe a rapid reduction of the magnon weight to zero, well before the system undergoes a deconfined quantum phase transition into a nonmagnetic spontaneously dimerized state. Based on these results, we reinterpret the picture of deconfined spinons at (π,0 in the experiments as nearly deconfined spinons—a precursor to deconfined quantum criticality. To further elucidate the picture of a fragile (π,0-magnon pole in the Heisenberg model and its depletion in the J-Q model, we introduce an effective model of the excitations in which a magnon can split into two spinons that do not separate but fluctuate in and out of the magnon space (in analogy to the resonance between a photon and a particle-hole pair in
Chiang, Mao-Hsiung
2010-01-01
This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.
Directory of Open Access Journals (Sweden)
Mao-Hsiung Chiang
2010-03-01
Full Text Available This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm and nanometer accuracy (20 nm. In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.
Critical properties of the Kitaev-Heisenberg Model
Sizyuk, Yuriy; Price, Craig; Perkins, Natalia
2013-03-01
Collective behavior of local moments in Mott insulators in the presence of strong spin-orbit coupling is one of the most interesting questions in modern condensed matter physics. Here we study the finite temperature properties of the Kitaev-Heisenberg model which describe the interactions between the pseudospin J = 1 / 2 iridium moments on the honeycomb lattice. This model was suggested as a possible model to explain low-energy physics of AIr2O3 compounds. In our study we show that the Kitaev-Heisenberg model may be mapped into the six state clock model with an intermediate power-law phase at finite temperatures. In the framework of the Ginsburg-Landau theory, we provide an analysis of the critical properties of the finite-temperature ordering transitions. NSF grant DMR-1005932
Radiation emission as a virtually exact realization of Heisenbergs microscope
Energy Technology Data Exchange (ETDEWEB)
Andersen, K.K., E-mail: kka@phys.au.dk [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C (Denmark); Brock, S. [Department of Culture and Society, Aarhus University, Jens Chr. Skous Vej 5, 8000 Aarhus C (Denmark); Esberg, J.; Thomsen, H.D.; Uggerhøj, U.I. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C (Denmark)
2013-11-15
Through the concept of ‘formation length’, recently observed directly in the radiation emission from ultrarelativistic electrons and an essential component in the interpretation of strong field radiation from electrons penetrating single crystals, we discuss the indeterminacy in the location of radiation emission. The analogy with the indeterminacy in the Heisenberg microscope Gedanken experiment is demonstrated from a number of viewpoints to be almost exact. The positive attitude regarding photon emission as a process that is somehow located in space and time is emphasized. We therefore interpret the measurements of formation lengths in radiation emission as a practically realizable version – using virtual incident photons instead of real – of the Heisenberg microscope Gedanken experiment.
Critical behavior of the XY-rotor model on regular and small-world networks
De Nigris, Sarah; Leoncini, Xavier
2013-07-01
We study the XY rotors model on small networks whose number of links scales with the system size Nlinks˜Nγ, where 1≤γ≤2. We first focus on regular one-dimensional rings in the microcanonical ensemble. For γ1.5, the system equilibrium properties are found to be identical to the mean field, which displays a second-order phase transition at a critical energy density ɛ=E/N,ɛc=0.75. Moreover, for γc≃1.5 we find that a nontrivial state emerges, characterized by an infinite susceptibility. We then consider small-world networks, using the Watts-Strogatz mechanism on the regular networks parametrized by γ. We first analyze the topology and find that the small-world regime appears for rewiring probabilities which scale as pSW∝1/Nγ. Then considering the XY-rotors model on these networks, we find that a second-order phase transition occurs at a critical energy ɛc which logarithmically depends on the topological parameters p and γ. We also define a critical probability pMF, corresponding to the probability beyond which the mean field is quantitatively recovered, and we analyze its dependence on γ.
Magnetization plateaus in the spin-1/2 antiferromagnetic Heisenberg model on a kagome-strip chain
Morita, Katsuhiro; Sugimoto, Takanori; Sota, Shigetoshi; Tohyama, Takami
2018-01-01
The spin-1/2 Heisenberg model on a kagome lattice is a typical frustrated quantum spin system. The basic structure of a kagome lattice is also present in the kagome-strip lattice in one dimension, where a similar type of frustration is expected. We thus study the magnetization plateaus of the spin-1/2 Heisenberg model on a kagome-strip chain with three-independent antiferromagnetic exchange interactions using the density-matrix renormalization-group method. In a certain range of exchange parameters, we find twelve kinds of magnetization plateaus, nine of which have magnetic structures breaking translational and/or reflection symmetry spontaneously. The structures are classified by an array of five-site unit cells with specific bond-spin correlations. In a case with a nontrivial plateau, namely a 3/10 plateau, we find long-period magnetic structure with a period of four unit cells.
Green function study of a mixed spin-((3)/(2)) and spin-((1)/(2)) Heisenberg ferrimagnetic model
International Nuclear Information System (INIS)
Li Jun; Wei Guozhu; Du An
2004-01-01
The magnetic properties of a mixed spin-((3)/(2)) and spin-((1)/(2)) Heisenberg ferrimagnetic system on a square lattice are investigated theoretically by a multisublattice Green-function technique which takes into account the quantum nature of Heisenberg spins. This model can be relevant for understanding the magnetic behavior of the new class of organometallic materials that exhibit spontaneous magnetic moments at room temperature. We discuss the spontaneous magnetic moments and the finite-temperature phase diagram. We find that there is no compensation point at finite temperature when only the nearest-neighbor interaction and the single-ion anisotropy are included. When the next-nearest-neighbor interaction between spin-((1)/(2)) is taken into account and exceeds a minimum value, a compensation point appears and it is basically unchanged for other values in Hamiltonian fixed. The next-nearest-neighbor interaction between spin-((3)/(2)) has the effect of changing the compensation temperature
International Nuclear Information System (INIS)
Zhong Ming; Tong Peiqing
2011-01-01
The Loschmidt echo (LE) of a central two-level qubit coupled to nonuniform anisotropic XY chains in a transverse field is studied. A general formula for LE is derived, which we use to discuss the influence of the criticality of the environment on LE. It is found that for the periodic XY chain the behaviors of LE in the vicinity of the critical points are similar to those of the uniform case. It is different for the disordered transverse Ising chains. For the aperiodic chains, if the surrounding systems are bounded chains, the behaviors of LE are similar to those of the uniform case, while if the surrounding systems are unbounded chains, they are similar to those of the disordered case.
Type-I integrable quantum impurities in the Heisenberg model
Energy Technology Data Exchange (ETDEWEB)
Doikou, Anastasia, E-mail: adoikou@upatras.gr
2013-12-21
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.
Type-I integrable quantum impurities in the Heisenberg model
International Nuclear Information System (INIS)
Doikou, Anastasia
2013-01-01
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
New relativistic generalization of the Heisenberg commutation relations
International Nuclear Information System (INIS)
Bohm, A.; Loewe, M.; Magnollay, P.; Tarlini, M.; Aldinger, R.R.; Kielanowski, P.
1984-01-01
A relativistic generalization of the Heisenberg commutation relations is suggested which is different from the conventional ones used for the intrinsic coordinates and momenta in the relativistic oscillator model and the relativistic string. This new quantum relativistic oscillator model is determined by the requirement that it gives a unified description of relativistic vibrations and rotations and contracts in the nonrelativistic limit c -1 →0 into the usual nonrelativistic harmonic oscillator
A rare case report of 46XY mixed gonadal dysgenesis
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Rakesh Arora
2013-01-01
Full Text Available A 16-year-old person, reared as female presented with complaints of genital ambiguity and primary amenorrhoea along with lack of secondary sexual characters, but without short stature and Turner′s stigmata. She was taking steroids after being misdiagnosed as congenital adrenal hyperplasia (CAH. Karyotype analysis revealed 46XY karyotype. There was no evidence of hypocortisolemia (cortisol 9.08 μg/dl, adrenocorticotropic hormone [ACTH] 82.5 pg/ml or elevated level of 17-OH-progesterone (0.16 ng/ml. Pooled luteinizing hormone (LH was 11.79 mIU/ml and follicle-stimulating hormone (FSH was 66.37 mIU/ml. Serum estradiol level was 25 pg/ml (21-251. Basal and 72 h post beta-human chorionic gonadotropin (hCG levels of androstenedione and testosterone levels were done (basal testosterone of 652 ng/dl and basal androstenedione of 1.17 ng/ml; 72 h post hCG testosterone of 896 ng/dl and androstenedione of 1.34 ng/ml. Magnetic resonance imaging (MRI pelvis (with ultrasonogrphy [USG] correlation revealed uterus didelphys with obstructed right moiety and bilateral ovarian-like structures. Right sided gonads and adjacent tubal structures were visualized laparoscopically and removed. Left sided gonads were not visualized and Mullerian remnants were adhered to sigmoid colon. Histopathological examination revealed presence of testicular tissue showing atrophic seminiferous tubules with hyperplasia of Leydig cells. No ovarian tissue was seen. Based on these results a diagnosis of 46XY mixed gonadal dysgenesis (MGD was made, which is rare and is difficult to distinguish from 46XY ovotesticular disorder of sexual differentiation (OT-DSD. The patient was managed with a multidisciplinary approach and fertility issues discussed with the patient′s caregivers.
Partial transpose of two disjoint blocks in XY spin chains
International Nuclear Information System (INIS)
Coser, Andrea; Tonni, Erik; Calabrese, Pasquale
2015-01-01
We consider the partial transpose of the spin reduced density matrix of two disjoint blocks in spin chains admitting a representation in terms of free fermions, such as XY chains. We exploit the solution of the model in terms of Majorana fermions and show that such partial transpose in the spin variables is a linear combination of four Gaussian fermionic operators. This representation allows to explicitly construct and evaluate the integer moments of the partial transpose. We numerically study critical XX and Ising chains and we show that the asymptotic results for large blocks agree with conformal field theory predictions if corrections to the scaling are properly taken into account. (paper)
SILENE and TDT: A code for collision probability calculations in XY geometries
International Nuclear Information System (INIS)
Sanchez, R.; Stankovski, Z.
1993-01-01
Collision probability methods are routinely used for cell and assembly multigroup transport calculations in core design tasks. Collision probability methods use a specialized tracking routine to compute neutron trajectories within a given geometric object. These trajectories are then used to generate the appropriate collision matrices in as many groups as required. Traditional tracking routines are based on open-quotes globalclose quotes geometric descriptions (such as regular meshes) and are not able to cope with the geometric detail required in actual core calculations. Therefore, users have to modify their geometry in order to match the geometric model accepted by the tracking routine, introducing thus a modeling error whose evaluation requires the use of a open-quotes referenceclose quotes method. Recently, an effort has been made to develop more flexible tracking routines either by directly adopting tracking Monte Carlo techniques or by coding of complicated geometries. Among these, the SILENE and TDT package is being developed at the Commissariat a l' Energie Atomique to provide routine as well as reference calculations in arbitrarily shaped XY geometries. This package combines a direct graphical acquisition system (SILENE) together with a node-based collision probability code for XY geometries (TDT)
Smectic-like phase for modulated XY spins in two dimensions
International Nuclear Information System (INIS)
Benakli, M.; Gabay, M.; Saslow, W.M.
1997-09-01
The row model for frustrated XY spins on a triangular lattice in 2D is used to study incommensurate (IC) and commensurate (C) phases, in the regime where a (C)-(IC) transition may be observed. Thermodynamic quantities for the (IC) state are computed analytically by means of the NSCHA, a new variational method appropriate for frustrated systems. On the commensurate side of the (C)-(IC) boundary, NSCHA predicts an instability of the (C) phase suggesting that this state is in fact spatially inhomogeneous. Detailed Monte-Carlo (MC) simulations using fluctuating boundary conditions and specific histogram techniques show that in this regime the configuration consists of stripes of (C) and (IC) phases alternating in space. This state, which resembles the smectic-A phase of liquid crystals, exists because of the strong coupling between chiral and phase (spin angle) variables. As a result, the transition between the (IC) and the (C) states can only occur at zero temperature T so that the Lifshitz point is at T = 0 for modulated XY spins in 2D. (author)
The Design of Control Pulses for Heisenberg Always-On Qubit Models
Magyar, Rudolph
2015-03-01
One model for a universal quantum computer is a spin array with constant nearest neighbor interactions and a controlled unidirectional site-specific magnetic field to generate unitary transformations. This system can be described by a Heisenberg spin Hamiltonian and can be simulated for on the order of 50 spins. It has recently been shown that time-dependent density functional inspired methods may be used to relate various spin models of qubits to ones that may be easier to compute numerically allowing potentially the efficient simulation of greater numbers of spins. One of the challenges of such an agenda is the identification of control pulses that produce desired gate operations (CNOT and single qubit phase gates). We apply control theory to design a universal set of pulses for a Heisenberg always-on model Hamiltonian for a few qubits and compare to known pulses when available. We suggest how this approach may be useful to design control pulses in other realistic designs. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Security Administration under contract DE-AC04-94AL85000.
Iridates and RuCl3 - from Heisenberg antiferromagnets to potential Kitaev spin-liquids
van den Brink, Jeroen
The observed richness of topological states on the single-electron level prompts the question what kind of topological phases can develop in more strongly correlated, many-body electron systems. Correlation effects, in particular intra- and inter-orbital electron-electron interactions, are very substantial in 3 d transition-metal compounds such as the copper oxides, but the spin-orbit coupling (SOC) is weak. In 5 d transition-metal compounds such as iridates, the interesting situation arises that the SOC and Coulomb interactions meet on the same energy scale. The electronic structure of iridates thus depends on a strong competition between the electronic hopping amplitudes, local energy-level splittings, electron-electron interaction strengths, and the SOC of the Ir 5d electrons. The interplay of these ingredients offers the potential to stabilise relatively well-understood states such as a 2D Heisenberg-like antiferromagnet in Sr2IrO4, but in principle also far more exotic ones, such a topological Kitaev quantum spin liquid, in (hyper)honeycomb iridates. I will discuss the microscopic electronic structures of these iridates, their proximity to idealized Heisenberg and Kitaev models and our contributions to establishing the physical factors that appear to have preempted the realization of quantum spin liquid phases so far and include a discussion on the 4d transition metal chloride RuCl3. Supported by SFB 1143 of the Deutsche Forschungsgemeinschaft.
International Nuclear Information System (INIS)
Li Jun; Wei Guozhu; Du An
2005-01-01
The compensation and critical behaviors of a mixed spin-2 and spin-12 Heisenberg ferrimagnetic system on a square lattice are investigated theoretically by the two-time Green's function technique, which takes into account the quantum nature of Heisenberg spins. The model can be relevant for understanding the magnetic behavior of the new class of organometallic ferromagnetic materials that exhibit spontaneous magnetic properties at room temperature. We carry out the calculation of the sublattice magnetizations and the spin-wave spectra of the ground state. In particular, we have studied the effects of the nearest, next-nearest-neighbor interactions, the crystal field and the external magnetic field on the compensation temperature and the critical temperature. When only the nearest-neighbor interactions and the crystal field are included, no compensation temperature exists; when the next-nearest-neighbor interaction between spin-12 is taken into account and exceeds a minimum value, a compensation point appears and it is basically unchanged for other parameters in Hamiltonian fixed. The next-nearest-neighbor interactions between spin-2 and the external magnetic field have the effects of changing the compensation temperature and there is a narrow range of parameters of the Hamiltonian for which the model has the compensation temperatures and compensation temperature exists only for a small value of them
Lee, Dong-Jin; Lee, Sun-Kyu
2015-01-01
This paper presents a design and control system for an XY stage driven by an ultrasonic linear motor. In this study, a hybrid bolt-clamped Langevin-type ultrasonic linear motor was manufactured and then operated at the resonance frequency of the third longitudinal and the sixth lateral modes. These two modes were matched through the preload adjustment and precisely tuned by the frequency matching method based on the impedance matching method with consideration of the different moving weights. The XY stage was evaluated in terms of position and circular motion. To achieve both fine and stable motion, the controller consisted of a nominal characteristics trajectory following (NCTF) control for continuous motion, dead zone compensation, and a switching controller based on the different NCTFs for the macro- and micro-dynamics regimes. The experimental results showed that the developed stage enables positioning and continuous motion with nanometer-level accuracy.
Lima, J. P. De; Gonçalves, L. L.
The critical dynamics of the isotropic XY-model on the one-dimensional superlattice is considered in the framework of the position space renormalization group theory. The decimation transformation is introduced by considering the equations of motion of the operators associated to the excitations of the system, and it corresponds to an extension of the procedure introduced by Stinchcombe and dos Santos (J. Phys. A18, L597 (1985)) for the homogeneous lattice. The dispersion relation is obtained exactly and the static and dynamic scaling forms are explicitly determined. The dynamic critical exponent is also obtained and it is shown that it is identical to the one of the XY-model on the homogeneous chain.
Heisenberg (and Schrödinger, and Pauli) on hidden variables
Bacciagaluppi, Guido; Crull, Elise
In this paper, we discuss various aspects of Heisenberg's thought on hidden variables in the period 1927-1935. We also compare Heisenberg's approach to others current at the time, specifically that embodied by von Neumann's impossibility proof, but also views expressed mainly in correspondence by Pauli and by Schrödinger. We shall base ourselves mostly on published and unpublished materials that are known but little-studied, among others Heisenberg's own draft response to the EPR paper. Our aim will be not only to clarify Heisenberg's thought on the hidden-variables question, but in part also to clarify how this question was understood more generally at the time.
Dynamical decoupling assisted acceleration of two-spin evolution in XY spin-chain environment
Energy Technology Data Exchange (ETDEWEB)
Wei, Yong-Bo; Zou, Jian [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Wang, Zhao-Ming [Department of Physics, Ocean University of China, Qingdao 266100 (China); Shao, Bin, E-mail: sbin610@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Li, Hai [School of Information and Electronic Engineering, Shandong Institute of Business and Technology, Yantai 264000 (China)
2016-01-28
We study the speed-up role of dynamical decoupling in an open system, which is modeled as two central spins coupled to their own XY spin-chain environment. We show that the fast bang–bang pulses can suppress the system evolution, which manifests the quantum Zeno effect. In contrast, with the increasing of the pulse interval time, the bang–bang pulses can enhance the decay of the quantum speed limit time and induce the speed-up process, which displays the quantum anti-Zeno effect. In addition, we show that the random pulses can also induce the speed-up of quantum evolution. - Highlights: • We propose a scheme to accelerate the dynamical evolution of central spins in an open system. • The quantum speed limit of central spins can be modulated by changing pulse frequency. • The random pulses can play the same role as the regular pulses do for small perturbation.
Energy Technology Data Exchange (ETDEWEB)
Brymora, Katarzyna; Calvayrac, Florent, E-mail: Florent.Calvayrac@univ-lemans.fr
2017-07-15
Highlights: • A new method is given to extract surface anisotropies from ab initio calculations. • Heisenberg model for magnetic clusters and surfaces is validated in simple cases. • Ligands, metallic clusters, or coatings degrade the validity of the Heisenberg model. • Values for surface anisotropies, volume anisotropies, exchange constants are computed. • Results are in agreement with experimental data, previous theoretical findings. - Abstract: We performed ab initio computations of the magnetic properties of simple iron oxide clusters and slabs. We considered an iron oxide cluster functionalized by a molecule or glued to a gold cluster of the same size. We also considered a magnetite slab coated by cobalt oxide or a mixture of iron oxide and cobalt oxide. The changes in magnetic behavior were explored using constrained magnetic calculations. A possible value for the surface anisotropy was estimated from the fit of a classical Heisenberg model on ab initio results. The value was found to be compatible with estimations obtained by other means, or inferred from experimental results. The addition of a ligand, coating, or of a metallic nanoparticle to the systems degraded the quality of the description by the Heisenberg Hamiltonian. Proposing a change in the anisotropies allowing for the proportion of each transition atom we could get a much better description of the magnetism of series of hybrid cobalt and iron oxide systems.
International Nuclear Information System (INIS)
Mishra, Utkarsh; Rakshit, Debraj; Prabhu, R; Sen, Aditi; Sen, Ujjwal
2016-01-01
Disordered systems form one of the centrestages of research in many body sciences and lead to a plethora of interesting phenomena and applications. A paradigmatic disordered system consists of a one-dimensional array of quantum spin-1/2 particles, governed by the Heisenberg spin glass Hamiltonian with natural or engineered quenched disordered couplings in an external magnetic field. These systems allow disorder-induced enhancement for bipartite and multipartite observables. Here we show that simultaneous application of independent quenched disorders results in disorder-induced enhancement, while the same is absent with individual application of the same disorders. We term the phenomenon as constructive interference and the corresponding parameter stretches as the Venus regions. Interestingly, it has only been observed for multiparty entanglement and is absent for the single- and two-party physical quantities. (paper)
The semi-infinite anisotropic spin-1/2 Heisenberg ferromagnet
International Nuclear Information System (INIS)
Benyoussef, A.; Boubekri, A.; Ez-Zahraouy, H.; Saber, M.
1998-08-01
Using the effective field theory with a probability distribution technique that accounts for the self-spin correlation functions, the phase transitions in the semi-infinite anisotropic spin-1/2 Heisenberg ferromagnet on a simple cubic lattice are examined. For fixed values of the reduced exchange anisotropic parameter, the critical temperature of the system is studied as a function of the ratio R of the surface exchange couplings to the bulk ones. It was found that if R ≤ R c , the system orders at the bulk critical temperature T B c /J and if R ≥ R c , the system exhibits two successive transitions. The surface orders at the surface critical temperature T S c /J which is higher than T B c /J and as the temperature is lowered, in the presence of ordered surface, the bulk orders at T B c /J. (author)
Du, Sienmi; Itoh, Noriko; Askarinam, Sahar; Hill, Haley; Arnold, Arthur P; Voskuhl, Rhonda R
2014-02-18
Women are more susceptible to multiple sclerosis (MS) and have more robust immune responses than men. However, men with MS tend to demonstrate a more progressive disease course than women, suggesting a disconnect between the severity of an immune attack and the CNS response to a given immune attack. We have previously shown in an MS model, experimental autoimmune encephalomyelitis, that autoantigen-sensitized XX lymph node cells, compared with XY, are more encephalitogenic. These studies demonstrated an effect of sex chromosomes in the induction of immune responses, but did not address a potential role of sex chromosomes in the CNS response to immune-mediated injury. Here, we examined this possibility using XX versus XY bone marrow chimeras reconstituted with a common immune system of one sex chromosomal type. We found that experimental autoimmune encephalomyelitis mice with an XY sex chromosome complement in the CNS, compared with XX, demonstrated greater clinical disease severity with more neuropathology in the spinal cord, cerebellum, and cerebral cortex. A candidate gene on the X chromosome, toll-like receptor 7, was then examined. Toll-like receptor 7 expression in cortical neurons was higher in mice with XY compared with mice with XX CNS, consistent with the known neurodegenerative role for toll-like receptor 7 in neurons. These results suggest that sex chromosome effects on neurodegeneration in the CNS run counter to effects on immune responses, and may bear relevance to the clinical enigma of greater MS susceptibility in women but faster disability progression in men. This is a demonstration of a direct effect of sex chromosome complement on neurodegeneration in a neurological disease.
Quantum chaos in the Heisenberg picture
International Nuclear Information System (INIS)
McKellar, B.H.J.; Lancaster, M.; McCaw, J.
2000-01-01
Full text: We explore the possibility of defining quantum chaos in the algebra of quantum mechanical operators. The simple definition of the Lyapunov exponent in terms of a metric on that algebra has the expected properties for the quantum logistic map, as we confirm for the simple spin 1 system. We then show numerically and analytically that the Hamiltonian evolution of finite spin systems does not lead to chaos in this definition, and investigate alternative definitions of quantum chaos in the algebra of operators
Performance Characterization of an xy-Stage Applied to Micrometric Laser Direct Writing Lithography
Directory of Open Access Journals (Sweden)
Juan Jaramillo
2017-01-01
Full Text Available This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP observed by a camera and image processing is based on Fourier transform and phase measurement methods. The results report that the built system has a stability against vibrations determined by peak-valley deviations of 65 nm and 26 nm in the x and y directions, respectively, with a standard deviation of 10 nm in both directions. When the xy-stage is in movement, it works with a resolution of 0.36 μm, which is an acceptable value for most of research and development (R and D microtechnology developments in which the typical feature size used is in the micrometer range.
Performance Characterization of an xy-Stage Applied to Micrometric Laser Direct Writing Lithography.
Jaramillo, Juan; Zarzycki, Artur; Galeano, July; Sandoz, Patrick
2017-01-31
This article concerns the characterization of the stability and performance of a motorized stage used in laser direct writing lithography. The system was built from commercial components and commanded by G-code. Measurements use a pseudo-periodic-pattern (PPP) observed by a camera and image processing is based on Fourier transform and phase measurement methods. The results report that the built system has a stability against vibrations determined by peak-valley deviations of 65 nm and 26 nm in the x and y directions, respectively, with a standard deviation of 10 nm in both directions. When the xy-stage is in movement, it works with a resolution of 0.36 μm, which is an acceptable value for most of research and development (R and D) microtechnology developments in which the typical feature size used is in the micrometer range.
Entanglement entropy of two disjoint blocks in XY chains
International Nuclear Information System (INIS)
Fagotti, Maurizio; Calabrese, Pasquale
2010-01-01
We study the Rényi entanglement entropies of two disjoint intervals in XY chains. We exploit the exact solution of the model in terms of free Majorana fermions and we show how to construct the reduced density matrix in the spin variables by taking the Jordan–Wigner string between the two blocks properly into account. From this we can evaluate any Rényi entropy of finite integer order. We study in detail critical XX and Ising chains and we show that the asymptotic results for large blocks agree with recent conformal field theory predictions if corrections to the scaling are included in the analysis correctly. We also report results for the gapped phase and after a quantum quench
Ellipses of constant entropy in the XY spin chain
International Nuclear Information System (INIS)
Franchini, F; Its, A R; Jin, B-Q; Korepin, V E
2007-01-01
Entanglement in the ground state of the XY model on the infinite chain can be measured by the von Neumann entropy of a block of neighbouring spins. We study a double scaling limit: the size of the block is much larger than 1 but much smaller than the length of the whole chain. The entropy of the block has an asymptotic limit in the gapped regimes. We study this limiting entropy as a function of the anisotropy and of the magnetic field. We identify its minima at product states and its divergencies at the quantum phase transitions. We find that the curves of constant entropy are ellipses and hyperbolas, and that they all meet at one point (essential critical point). Depending on the approach to the essential critical point, the entropy can take any value between 0 and ∞. In the vicinity of this point, small changes in the parameters cause large change of the entropy
Logarithmic corrections to scaling in the XY2-model
International Nuclear Information System (INIS)
Kenna, R.; Irving, A.C.
1995-01-01
We study the distribution of partition function zeroes for the XY-model in two dimensions. In particular we find the scaling behaviour of the end of the distribution of zeroes in the complex external magnetic field plane in the thermodynamic limit (the Yang-Lee edge) and the form for the density of these zeroes. Assuming that finite-size scaling holds, we show that there have to exist logarithmic corrections to the leading scaling behaviour of thermodynamic quantities in this model. These logarithmic corrections are also manifest in the finite-size scaling formulae and we identify them numerically. The method presented here can be used to check the compatibility of scaling behaviour of odd and even thermodynamic functions in other models too. ((orig.))
Development of x-y table for baby electron beam detection using dispose printer
International Nuclear Information System (INIS)
Leo Kwee Wah; Mohd Rizal Md Chulan; Muhamad Zahidee Taat; Abu Bakar Md Ghazali; Mohamad Nor Atan; Siti A'iasah Hashim
2005-01-01
This paper describes the development of X-Y table using the dispose printer. It consists the mechanical part and the control (Interfacing and software/programming) part description. As the result, the x-y table will be used to moves the electron beam detector for the baby electron beam machine. (Author)
Graphical Representation of Complex Solutions of the Quadratic Equation in the "xy" Plane
McDonald, Todd
2006-01-01
This paper presents a visual representation of complex solutions of quadratic equations in the xy plane. Rather than moving to the complex plane, students are able to experience a geometric interpretation of the solutions in the xy plane. I am also working on these types of representations with higher order polynomials with some success.
Q-operators for the open Heisenberg spin chain
Directory of Open Access Journals (Sweden)
Rouven Frassek
2015-12-01
Full Text Available We construct Q-operators for the open spin-12 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.
Quantum spin circulator in Y junctions of Heisenberg chains
Buccheri, Francesco; Egger, Reinhold; Pereira, Rodrigo G.; Ramos, Flávia B.
2018-06-01
We show that a quantum spin circulator, a nonreciprocal device that routes spin currents without any charge transport, can be achieved in Y junctions of identical spin-1 /2 Heisenberg chains coupled by a chiral three-spin interaction. Using bosonization, boundary conformal field theory, and density matrix renormalization group simulations, we find that a chiral fixed point with maximally asymmetric spin conductance arises at a critical point separating a regime of disconnected chains from a spin-only version of the three-channel Kondo effect. We argue that networks of spin-chain Y junctions provide a controllable approach to construct long-sought chiral spin-liquid phases.
From linear optical quantum computing to Heisenberg-limited interferometry
International Nuclear Information System (INIS)
Lee, Hwang; Kok, Pieter; Williams, Colin P; Dowling, Jonathan P
2004-01-01
The working principles of linear optical quantum computing are based on photodetection, namely, projective measurements. The use of photodetection can provide efficient nonlinear interactions between photons at the single-photon level, which is technically problematic otherwise. We report an application of such a technique to prepare quantum correlations as an important resource for Heisenberg-limited optical interferometry, where the sensitivity of phase measurements can be improved beyond the usual shot-noise limit. Furthermore, using such nonlinearities, optical quantum non-demolition measurements can now be carried out easily at the single-photon level
Collective impurity effects in the Heisenberg triangular antiferromagnet
International Nuclear Information System (INIS)
Maryasin, V S; Zhitomirsky, M E
2015-01-01
We theoretically investigate the Heisenberg antiferromagnet on a triangular lattice doped with nonmagnetic impurities. Two nontrivial effects resulting from collective impurity behavior are predicted. The first one is related to presence of uncompensated magnetic moments localized near vacancies as revealed by the low-temperature Curie tail in the magnetic susceptibility. These moments exhibit an anomalous growth with the impurity concentration, which we attribute to the clustering mechanism. In an external magnetic field, impurities lead to an even more peculiar phenomenon lifting the classical ground-state degeneracy in favor of the conical state. We analytically demonstrate that vacancies spontaneously generate a positive biquadratic exchange, which is responsible for the above degeneracy lifting
Directory of Open Access Journals (Sweden)
Christoph P. Hofmann
2016-03-01
Full Text Available The low-temperature properties of systems characterized by a spontaneously broken internal rotation symmetry, O(N→O(N−1, are governed by Goldstone bosons and can be derived systematically within effective Lagrangian field theory. In the present study we consider systems living in two spatial dimensions, and evaluate their partition function at low temperatures and weak external fields up to three-loop order. Although our results are valid for any such system, here we use magnetic terminology, i.e., we refer to quantum spin systems. We discuss the sign of the (pseudo-Goldstone boson interaction in the pressure, staggered magnetization, and susceptibility as a function of an external staggered field for general N. As it turns out, the d=2+1 quantum XY model (N=2 and the d=2+1 Heisenberg antiferromagnet (N=3, are rather special, as they represent the only cases where the spin-wave interaction in the pressure is repulsive in the whole parameter regime where the effective expansion applies. Remarkably, the d=2+1 XY model is the only system where the interaction contribution in the staggered magnetization (susceptibility tends to positive (negative values at low temperatures and weak external field.
Emergent criticality and Friedan scaling in a two-dimensional frustrated Heisenberg antiferromagnet
Orth, Peter P.; Chandra, Premala; Coleman, Piers; Schmalian, Jörg
2014-03-01
We study a two-dimensional frustrated Heisenberg antiferromagnet on the windmill lattice consisting of triangular and dual honeycomb lattice sites. In the classical ground state, the spins on different sublattices are decoupled, but quantum and thermal fluctuations drive the system into a coplanar state via an "order from disorder" mechanism. We obtain the finite temperature phase diagram using renormalization group approaches. In the coplanar regime, the relative U(1) phase between the spins on the two sublattices decouples from the remaining degrees of freedom, and is described by a six-state clock model with an emergent critical phase. At lower temperatures, the system enters a Z6 broken phase with long-range phase correlations. We derive these results by two distinct renormalization group approaches to two-dimensional magnetism: Wilson-Polyakov scaling and Friedan's geometric approach to nonlinear sigma models where the scaling of the spin stiffnesses is governed by the Ricci flow of a 4D metric tensor.
Adiabatically modeling quantum gates with two-site Heisenberg spins chain: Noise vs interferometry
Jipdi, M. N.; Tchoffo, M.; Fai, L. C.
2018-02-01
We study the Landau Zener (LZ) dynamics of a two-site Heisenberg spin chain assisted with noise and focus on the implementation of logic gates via the resulting quantum interference. We present the evidence of the quantum interference phenomenon in triplet spin states and confirm that, three-level systems mimic Landau-Zener-Stückelberg (LZS) interferometers with occupancies dependent on the effective phase. It emerges that, the critical parameters tailoring the system are obtained for constructive interferences where the two sets of the chain are found to be maximally entangled. Our findings demonstrate that the enhancement of the magnetic field strength suppresses noise effects; consequently, the noise severely impacts the occurrence of quantum interference for weak magnetic fields while for strong fields, quantum interference subsists and allows the modeling of universal sets of quantum gates.
Xu, Ping; Du, An
2017-09-01
A superlattice composed of spin-1 and spin-2 with ABAB … structure was described with Heisenberg model. The magnetizations and magnetic entropy changes under different magnetic fields were calculated by the Green's function method. The magnetization compensation phenomenon could be observed by altering the intralayer exchange interactions and the single-ion anisotropies of spins. Along with the temperature increasing, the system in the absence of magnetization compensation shows normal magnetic entropy change and displays a peak near the critical temperature, and yet the system with magnetization compensation shows normal magnetic entropy change near the compensation temperature but inverse magnetic entropy change near the critical temperature. Finally, we illustrated the reasons of different behaviors of magnetic entropy change by analyzing the contributions of two sublattices to the total magnetic entropy change.
Heisenberg Groups as Platform for the AAG key-exchange protocol
Kahrobaei, Delaram; Lam, Ha T.
2014-01-01
Garber, Kahrobaei, and Lam studied polycyclic groups generated by number field as platform for the AAG key-exchange protocol. In this paper, we discuss the use of a different kind of polycyclic groups, Heisenberg groups, as a platform group for AAG by submitting Heisenberg groups to one of AAG's major attacks, the length-based attack.
DEFF Research Database (Denmark)
Berglund, Agnethe; Johannsen, Trine H; Stochholm, Kirstine
2018-01-01
Context: Little is known about long-term health outcomes in phenotypic females with 46,XY disorders of sex development (XY females) and the socioeconomic profile is not described in detail. Objective: To describe morbidity, mortality and socioeconomic status in XY females in a comparison...... the general population. Interventions: None. Main outcome measures: combined mortality and morbidity as well as chapter-specific morbidity. Medicinal use and socioeconomic profile, including education, cohabitation and retirement. Results: Compared to female controls overall morbidity was increased in XY...... closely related to the DSD condition. Judged on educational level and income XY females perform well on the labor market. However, DSD seems to impact on the prospects of family life.....
DEFF Research Database (Denmark)
Berglund, Agnethe; Johannsen, Trine H; Krag, Kirstine Stochholm
2016-01-01
CONTEXT: The prevalence of phenotypic females with a 46,XY karyotype is low, thus current knowledge about age and clinical presentation at diagnosis is sparse even for the most frequent conditions, androgen insensitivity syndrome (AIS), and gonadal dysgenesis. OBJECTIVE: To estimate incidence......, prevalence, age at diagnosis, and clinical presentation at diagnosis in 46,XY females. DESIGN AND SETTING: A nationwide study covering all known females with a 46,XY karyotype in Denmark since 1960. The diagnosis of 46,XY disorder of sex development (DSD) was determined by medical record evaluation, data.......0-13.5; range, 0-34 y) in AIS and 17.0 years (95% confidence interval, 15.5-19.0; range, 0-28 y) in gonadal dysgenesis (P = .001). Clinical presentation was dependent on cause of DSD. CONCLUSIONS: The first estimate on prevalence of 46,XY females is 6.4 per 100 000 live born females. The presentation of AIS...
Interaction of a single mode field cavity with the 1D XY model: Energy spectrum
International Nuclear Information System (INIS)
Tonchev, H; Donkov, A A; Chamati, H
2016-01-01
In this work we use the fundamental in quantum optics Jaynes-Cummings model to study the response of spin 1/2chain to a single mode of a laser light falling on one of the spins, a focused interaction model between the light and the spin chain. For the spin-spin interaction along the chain we use the XY model. We report here the exact analytical results, obtained with the help of a computer algebra system, for the energy spectrum in this model for chains of up to 4 spins with nearest neighbors interactions, either for open or cyclic chain configurations. Varying the sign and magnitude of the spin exchange coupling relative to the light-spin interaction we have investigated both cases of ferromagnetic or antiferromagnetic spin chains. (paper)
Theory X/Y in the Health Care Setting: Employee Perceptions, Attitudes, and Behaviors.
Prottas, David J; Nummelin, Mary Rogers
Douglas McGregor's conceptualization of Theory X and Theory Y has influenced management practices for almost six decades, despite the relative paucity of empirical support. This empirical study examined the relationships between health care employees' perceptions of (1) manager Theory Y and Theory X orientations; (2) work unit psychological safety, organizational citizenship behavior, and service quality; and (3) the employing entity. The study used survey data from more than 3500 employees of a large US health care system and analyzed them using confirmatory factor and hierarchical regression analyses. Results indicate that McGregor's conceptualization is best considered as two separate constructs-Theory Y and Theory X-rather than as one-dimensional X/Y construct. This study's three dependent variables were positively related to Theory Y and negatively related to Theory X, with larger Theory Y effect sizes. Psychological safety partially mediated the relationship between Theory Y and the dependent variables Y. Practical implications are presented.
The phase transition in the anisotropic Heisenberg model with long range dipolar interactions
International Nuclear Information System (INIS)
Mól, L.A.S.; Costa, B.V.
2014-01-01
In this work we have used extensive Monte Carlo calculations to study the planar to paramagnetic phase transition in the two-dimensional anisotropic Heisenberg model with dipolar interactions (AHd) considering the true long-range character of the dipolar interactions by means of the Ewald summation. Our results are consistent with an order–disorder phase transition with unusual critical exponents in agreement with our previous results for the Planar Rotator model with dipolar interactions. Nevertheless, our results disagree with the Renormalization Group results of Maier and Schwabl [Phys. Rev. B, 70, 134430 (2004)] [13] and the results of Rapini et al. [Phys. Rev. B, 75, 014425 (2007)] [12], where the AHd was studied using a cut-off in the evaluation of the dipolar interactions. We argue that besides the long-range character of dipolar interactions their anisotropic character may have a deeper effect in the system than previously believed. Besides, our results show that the use of a cut-off radius in the evaluation of dipolar interactions must be avoided when analyzing the critical behavior of magnetic systems, since it may lead to erroneous results. - Highlights: • The anisotropic Heisenberg model with dipolar interactions is studied. • True long-range interactions were considered by means of Ewald summation. • We found an order–disorder phase transition with unusual critical exponents. • Previous results show a different behavior when a cut-off radius is introduced. • The use of a cut-off radius must be avoided when dealing with dipolar systems
Fermionology in the Kondo-Heisenberg model: the case of CeCoIn5
Zhong, Yin; Zhang, Lan; Lu, Han-Tao; Luo, Hong-Gang
2015-09-01
The Fermi surface of heavy electron systems plays a fundamental role in understanding their variety of puzzling phenomena, for example, quantum criticality, strange metal behavior, unconventional superconductivity and even enigmatic phases with yet unknown order parameters. The spectroscopy measurement of the typical heavy fermion superconductor CeCoIn5 has demonstrated multi-Fermi surface structure, which has not been studied in detail theoretically in a model system like the Kondo-Heisenberg model. In this work, we take a step toward such a theoretical model by revisiting the Kondo-Heisenberg model. It is found that the usual self-consistent calculation cannot reproduce the fermionology of the experimental observation of the system due to the sign binding between the hopping of the conduction electrons and the mean-field valence-bond order. To overcome such inconsistency, the mean-field valence-bond order is considered as a free/fitting parameter to correlate them with real-life experiments as performed in recent experiments [M.P. Allan, F. Massee, D.K. Morr, J. Van Dyke, A.W. Rost, A.P. Mackenzie, C. Petrovic, J.C. Davis, Nat. Phys. 9, 468 (2013); J. Van Dyke, F. Massee, M.P. Allan, J.C. Davis, C. Petrovic, D.K. Morr, Proc. Natl. Acad. Sci. 111, 11663 (2014)], which also explicitly reflects the intrinsic dispersion of local electrons observed in experimental measurements. Given the fermionology, the calculated effective mass enhancement, entropy, superfluid density and Knight shift are all in qualitative agreement with the experimental results of CeCoIn5, which confirms our assumption. Our result supports a d_{x^2 - y^2 }-wave pairing structure in the heavy fermion material CeCoIn5.
Realistic Approach of the Relations of Uncertainty of Heisenberg
Directory of Open Access Journals (Sweden)
Paul E. Sterian
2013-01-01
Full Text Available Due to the requirements of the principle of causality in the theory of relativity, one cannot make a device for the simultaneous measuring of the canonical conjugate variables in the conjugate Fourier spaces. Instead of admitting that a particle’s position and its conjugate momentum cannot be accurately measured at the same time, we consider the only probabilities which can be determined when working at subatomic level to be valid. On the other hand, based on Schwinger's action principle and using the quadridimensional form of the unitary transformation generator function of the quantum operators in the paper, the general form of the evolution equation for these operators is established. In the nonrelativistic case one obtains the Heisenberg's type evolution equations which can be particularized to derive Heisenberg's uncertainty relations. The analysis of the uncertainty relations as implicit evolution equations allows us to put into evidence the intrinsic nature of the correlation expressed by these equations in straight relations with the measuring process. The independence of the quantisation postulate from the causal evolution postulate of quantum mechanics is also put into discussion.
Heisenberg's war. The secret history of the German bomb
International Nuclear Information System (INIS)
Powers, T.
1993-01-01
The history of Second World War Germany's 'Uranium Project', which often is referred to as the 'myth of the German atomic bomb', has been attracting the mind's of secret service men, futurologists, historians and journalists since after the end of the war it has become possible to lift the veil of secrecy. Powers book adds another one to the many investigations published since them. His approach to the piece of history starts with Heisenberg's visit to the U.S.A. in summer 1939, describes the plans of the German Heereswaffenamt pursued with the Uranium Project, and their counterpart on the side of the Allied Forces where German scientists, as immigrants in England and in the U.S.A., were doing their best to launch research for the development of an atomic bomb. The end of this 'competition' is marked by the internment of the ten German scientists and bomb specialists in Fall Hall. The leading story of the book centers on the small group of scientists around Heisenberg, who cleverly 'torpedoed' the development of the German atomic bomb in the years from 1939 until 1944. (HP) [de
Linearized pseudo-Einstein equations on the Heisenberg group
Barletta, Elisabetta; Dragomir, Sorin; Jacobowitz, Howard
2017-02-01
We study the pseudo-Einstein equation R11bar = 0 on the Heisenberg group H1 = C × R. We consider first order perturbations θɛ =θ0 + ɛ θ and linearize the pseudo-Einstein equation about θ0 (the canonical Tanaka-Webster flat contact form on H1 thought of as a strictly pseudoconvex CR manifold). If θ =e2uθ0 the linearized pseudo-Einstein equation is Δb u - 4 | Lu|2 = 0 where Δb is the sublaplacian of (H1 ,θ0) and L bar is the Lewy operator. We solve the linearized pseudo-Einstein equation on a bounded domain Ω ⊂H1 by applying subelliptic theory i.e. existence and regularity results for weak subelliptic harmonic maps. We determine a solution u to the linearized pseudo-Einstein equation, possessing Heisenberg spherical symmetry, and such that u(x) → - ∞ as | x | → + ∞.
Ekberg, Peter; Mattsson, Lars
2018-03-01
Coherence scanning interferometry used in optical profilers are typically good for Z-calibration at nm-levels, but the X,Y accuracy is often left without further notice than typical resolution limits of the optics, i.e. of the order of ~1 µm. For the calibration of metrology tools we rely on traceable artefacts, e.g. gauge blocks for traditional coordinate measurement machines, and lithographically mask made artefacts for microscope calibrations. In situations where the repeatability and accuracy of the measurement tool is much better than the uncertainty of the traceable artefact, we are bound to specify the uncertainty based on the calibration artefact rather than on the measurement tool. This is a big drawback as the specified uncertainty of a calibrated measurement may shrink the available manufacturing tolerance. To improve the uncertainty in X,Y we can use self-calibration. Then, we do not need to know anything more than that the artefact contains a pattern with some nominal grid. This also gives the opportunity to manufacture the artefact in-house, rather than buying a calibrated and expensive artefact. The self-calibration approach we present here is based on an iteration algorithm, rather than the traditional mathematical inversion, and it leads to much more relaxed constrains on the input measurements. In this paper we show how the X,Y errors, primarily optical distortions, within the field of view (FOV) of an optical coherence scanning interferometry microscope, can be reduced with a large factor. By self-calibration we achieve an X,Y consistency in the 175 × 175 µm2 FOV of ~2.3 nm (1σ) using the 50× objective. Besides the calibrated coordinate X,Y system of the microscope we also receive, as a bonus, the absolute positions of the pattern in the artefact with a combined uncertainty of 6 nm (1σ) by relying on a traceable 1D linear measurement of a twin artefact at NIST.
Quantum state transfer via a two-qubit Heisenberg XXZ spin model
Energy Technology Data Exchange (ETDEWEB)
Liu Jia; Zhang Guofeng [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Chen Ziyu [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)], E-mail: chenzy@buaa.edu.cn
2008-04-14
Transfer of quantum states through a two-qubit Heisenberg XXZ spin model with a nonuniform magnetic field b is investigated by means of quantum theory. The influences of b, the spin exchange coupling J and the effective transfer time T=Jt on the fidelity have been studied for some different initial states. Results show that fidelity of the transferred state is determined not only by J, T and b but also by the initial state of this quantum system. Ideal information transfer can be realized for some kinds of initial states. We also found that the interactions of the z-component J{sub z} and uniform magnetic field B do not have any contribution to the fidelity. These results may be useful for quantum information processing.
Quantum state transfer via a two-qubit Heisenberg XXZ spin model
International Nuclear Information System (INIS)
Liu Jia; Zhang Guofeng; Chen Ziyu
2008-01-01
Transfer of quantum states through a two-qubit Heisenberg XXZ spin model with a nonuniform magnetic field b is investigated by means of quantum theory. The influences of b, the spin exchange coupling J and the effective transfer time T=Jt on the fidelity have been studied for some different initial states. Results show that fidelity of the transferred state is determined not only by J, T and b but also by the initial state of this quantum system. Ideal information transfer can be realized for some kinds of initial states. We also found that the interactions of the z-component J z and uniform magnetic field B do not have any contribution to the fidelity. These results may be useful for quantum information processing
Evolution in totally constrained models: Schrödinger vs. Heisenberg pictures
Olmedo, Javier
2016-06-01
We study the relation between two evolution pictures that are currently considered for totally constrained theories. Both descriptions are based on Rovelli’s evolving constants approach, where one identifies a (possibly local) degree of freedom of the system as an internal time. This method is well understood classically in several situations. The purpose of this paper is to further analyze this approach at the quantum level. Concretely, we will compare the (Schrödinger-like) picture where the physical states evolve in time with the (Heisenberg-like) picture in which one defines parametrized observables (or evolving constants of the motion). We will show that in the particular situations considered in this paper (the parametrized relativistic particle and a spatially flat homogeneous and isotropic spacetime coupled to a massless scalar field) both descriptions are equivalent. We will finally comment on possible issues and on the genericness of the equivalence between both pictures.
Quantum Teleportation via Completely Anisotropic Heisenberg Chain in Inhomogeneous Magnetic Field
Institute of Scientific and Technical Information of China (English)
FU Cheng-Hua; HU Zhan-Ning
2013-01-01
The quantum teleportation with the entangled thermal state is investigated based on the completely anisotropic Heisenberg chain in the presence of the externally inhomogeneous magnetic field.The effects of the anisotropy and magnetic field for the quantum fidefity are studied in detail.The zero temperature limit and the features of the nonzero temperature for this nonclassical fidelity are obtained.We find that the quantum teleportation demands more stringent conditions than the thermal entanglement of the resource by investigating the threshold temperature of the thermal concurrence and the critical temperature of the maximal teleportation fidelity.The useful quantum teleportation should avoid the point of the phase transition of the system and the anisotropy of the chain and the external magnetic field can control the applicability of the resource in the quantum teleportation.
Energy Technology Data Exchange (ETDEWEB)
Kosmachev, O. A.; Krivtsova, A. V.; Fridman, Yu. A., E-mail: yuriifridman@gmail.com [Vernadskii Crimea Federal University (Russian Federation)
2016-02-15
We study the effect of interionic anisotropy on the phase states of a non-Heisenberg ferromagnet with magnetic ion spin S = 1. It is shown that depending on the relation between the interionic anisotropy constants, uniaxial and angular ferromagnetic and nonmagnetic phases exist in the system. We analyze the dynamic properties of the system in the vicinity of orientational phase transitions, as well as a phase transition in the magnetic moment magnitude. It is shown that orientational phase transitions in ferromagnetic and nematic phases can be first- as well as second-order.
Berglund, Agnethe; Johannsen, Trine H; Stochholm, Kirstine; Viuff, Mette H; Fedder, Jens; Main, Katharina M; Gravholt, Claus H
2016-12-01
The prevalence of phenotypic females with a 46,XY karyotype is low, thus current knowledge about age and clinical presentation at diagnosis is sparse even for the most frequent conditions, androgen insensitivity syndrome (AIS), and gonadal dysgenesis. To estimate incidence, prevalence, age at diagnosis, and clinical presentation at diagnosis in 46,XY females. A nationwide study covering all known females with a 46,XY karyotype in Denmark since 1960. The diagnosis of 46,XY disorder of sex development (DSD) was determined by medical record evaluation, data from the Danish National Patient Registry, and genetic testing, if available. A total of 166 females registered as 46,XY females in the Danish Cytogenetic Central Registry were identified. A total of 124 females were classified as having 46,XY DSD, 78 with AIS and 25 with gonadal dysgenesis, whereas the remaining subjects had a variety of different diagnoses. The prevalence of 46,XY females was 6.4 per 100 000 live born females, and for AIS and gonadal dysgenesis, it was 4.1 and 1.5 per 100 000, respectively. Median age at diagnosis was 7.5 years (95% confidence interval, 4.0-13.5; range, 0-34 y) in AIS and 17.0 years (95% confidence interval, 15.5-19.0; range, 0-28 y) in gonadal dysgenesis (P = .001). Clinical presentation was dependent on cause of DSD. The first estimate on prevalence of 46,XY females is 6.4 per 100 000 live born females. The presentation of AIS and gonadal dysgenesis is distinctly different, with AIS being diagnosed during childhood and gonadal dysgenesis during pubertal years. The presenting phenotype is dependent on the cause of 46,XY DSD.
Exact solution to the moment problem for the XY chain
International Nuclear Information System (INIS)
Witte, N.S.
1996-01-01
We present the exact solution to the moment problem for the spin-1/2 isotropic antiferromagnetic XY chain with explicit forms for the moments with respect to the Neel state, the cumulant generating function, and the Resolvent Operator. We verify the correctness of the Horn-Weinstein Theorems, but the analytic structure of the generating function (e -tH ) in the complex t-plane is quite different from that assumed by the t-Expansion and the Connected Moments Expansion due to the vanishing gap. This function has a finite radius of convergence about t = 0, and for large 't' has a leading descending algebraic series E(t)-E o ∼ At -2 . The Resolvent has a branch cut and essential singularity near the ground state energy of the form G(s)/s∼B|s+1| -3/4 exp(C|s+1| 1/2 ). Consequently extrapolation strategies based on these assumptions are flawed and in practice we find that the CMX methods are pathological and cannot be applied, while numerical evidence for two of the t-expansion methods indicates a clear asymptotic convergence behaviour with truncation order. (author). 28 refs., 2 figs
Yang, Qi; Cao, Yue; Chen, Shiyin; Teng, Yue; Meng, Yanli; Wang, Gangcheng; Sun, Chunfang; Xue, Kang
2018-06-01
In this paper, we construct a new set of orthonormal topological basis states for six qubits with the topological single loop d = 2. By acting on the subspace, we get a new five-dimensional (5 D) reduced matrix. In addition, it is shown that the Heisenberg XXX spin-1/2 chain of six qubits can be constructed from the Temperley-Lieb algebra (TLA) generator, both the energy ground state and the spin singlet states of the system can be described by the set of topological basis states.
Kouri, Donald J; Markovich, Thomas; Maxwell, Nicholas; Bodmann, Bernhard G
2009-07-02
We discuss a periodic variant of the Heisenberg-Weyl algebra, associated with the group of translations and modulations on the circle. Our study of uncertainty minimizers leads to a periodic version of canonical coherent states. Unlike the canonical, Cartesian case, there are states for which the uncertainty product associated with the generators of the algebra vanishes. Next, we explore the supersymmetric (SUSY) quantum mechanical setting for the uncertainty-minimizing states and interpret them as leading to a family of "hindered rotors". Finally, we present a standard quantum mechanical treatment of one of these hindered rotor systems, including numerically generated eigenstates and energies.
Yang, Qi; Cao, Yue; Chen, Shiyin; Teng, Yue; Meng, Yanli; Wang, Gangcheng; Sun, Chunfang; Xue, Kang
2018-03-01
In this paper, we construct a new set of orthonormal topological basis states for six qubits with the topological single loop d = 2. By acting on the subspace, we get a new five-dimensional (5D) reduced matrix. In addition, it is shown that the Heisenberg XXX spin-1/2 chain of six qubits can be constructed from the Temperley-Lieb algebra (TLA) generator, both the energy ground state and the spin singlet states of the system can be described by the set of topological basis states.
International Nuclear Information System (INIS)
Kavitha, L.; Daniel, M.
2002-07-01
The integrability of one dimensional classical continuum inhomogeneous biquadratic Heisenberg spin chain and the effect of nonlinear inhomogeneity on the soliton of an underlying completely integrable spin model are studied. The dynamics of the spin system is expressed in terms of a higher order generalized nonlinear Schroedinger equation through a differential geometric approach which becomes integrable for a particular choice of the biquadratic exchange interaction and for linear inhomogeneity. The effect of nonlinear inhomogeneity on the spin soliton is studied by carrying out a multiple scale perturbation analysis. (author)
International Nuclear Information System (INIS)
Lobashev, A.A.; Mostepanenko, V.M.
1993-01-01
Heisenberg formalism is developed for creation-annihilation operators of quantum fields propagating in nonstationary external fields. Quantum fields with spin 0,1/2, 1 are considered in the presence of such external fields as electromagnetic, scalar and the field of nonstationary dielectric properties of nonlinear medium. Elliptic operator parametrically depending on time is constructed. In Heisenberg representation field variables are decomposed over eigenfunction of this operator. The relation between Heisenberg creation-annihilation operators and the operators obtained in the frame of diagonalization of Hamiltonian with Bogoliubov transformations is set up
International Nuclear Information System (INIS)
Bhan, Jaemi; Kwon, Younghun
2007-01-01
Recently Yeo showed that thermal states in Heisenberg XX model with periodic boundary condition could be used for three-party quantum teleportation. However it is hard to implement the periodic boundary condition in spin chain. So instead of imposing the periodic boundary condition, we consider open boundary condition in Heisenberg XX model and investigate the possibility of using thermal states in Heisenberg XX model with open boundary condition. Using this way, we find the best fidelity conditions to three known protocols in three-party quantum teleportation. It turns out that the best fidelity in every protocol would be 23
Computational Fluid Dynamics (CFD) simulations of a Heisenberg Vortex Tube
Bunge, Carl; Sitaraman, Hariswaran; Leachman, Jake
2017-11-01
A 3D Computational Fluid Dynamics (CFD) simulation of a Heisenberg Vortex Tube (HVT) is performed to estimate cooling potential with cryogenic hydrogen. The main mechanism driving operation of the vortex tube is the use of fluid power for enthalpy streaming in a highly turbulent swirl in a dual-outlet tube. This enthalpy streaming creates a temperature separation between the outer and inner regions of the flow. Use of a catalyst on the peripheral wall of the centrifuge enables endothermic conversion of para-ortho hydrogen to aid primary cooling. A κ- ɛ turbulence model is used with a cryogenic, non-ideal equation of state, and para-orthohydrogen species evolution. The simulations are validated with experiments and strategies for parametric optimization of this device are presented.
Anisotropic Heisenberg model for a semi-infinite crystal
International Nuclear Information System (INIS)
Queiroz, C.A.
1985-11-01
A semi-infinite Heisenberg model with exchange interactions between nearest and next-nearest neighbors in a simple cubic lattice. The free surface from the other layers of magnetic ions, by choosing a single ion uniaxial anisotropy in the surface (Ds) different from the anisotropy in the other layers (D). Using the Green function formalism, the behavior of magnetization as a function of the temperature for each layer, as well as the spectrum localized magnons for several values of ratio Ds/D for surface magnetization. Above this critical ratio, a ferromagnetic surface layer is obtained white the other layers are already in the paramagnetic phase. In this situation the critical temperature of surface becomes larger than the critical temperature of the bulk. (Author) [pt
Quantum Kalman filtering and the Heisenberg limit in atomic magnetometry
Energy Technology Data Exchange (ETDEWEB)
Geremia, J M; Stockton, John K; Doherty, Andrew C; Mabuchi, Hideo [Norman Bridge Laboratory of Physics, California Institute of Technology, Pasadena, California, 91125 (United States)
2003-12-19
The shot-noise detection limit in current high-precision magnetometry [I. Kominis, T. Kornack, J. Allred, and M. Romalis, Nature (London) 422, 596 (2003)]10.1038/nature01484 is a manifestation of quantum fluctuations that scale as 1/{radical}(N) in an ensemble of N atoms. Here, we develop a procedure that combines continuous measurement and quantum Kalman filtering [V. Belavkin, Rep. Math. Phys. 43, 405 (1999)] to surpass this conventional limit by exploiting conditional spin squeezing to achieve 1/N field sensitivity. Our analysis demonstrates the importance of optimal estimation for high bandwidth precision magnetometry at the Heisenberg limit and also identifies an approximate estimator based on linear regression.
Evolution of topological features in finite antiferromagnetic Heisenberg chains
International Nuclear Information System (INIS)
Chen Changfeng
2003-01-01
We examine the behavior of nonlocal topological order in finite antiferromagnetic Heisenberg chains using the density matrix renormalization group techniques. We find that chains with even and odd site parity show very different behavior in the topological string order parameter, reflecting interesting interplay of the intrinsic magnetic correlation and the topological term in the chains. Analysis of the calculated string order parameter as a function of the chain length and the topological angle indicates that S=1/2 and S=1 chains show special behavior while all S>1 chains have similar topological structure. This result supports an earlier conjecture on the classification of quantum spin chains based on an analysis of their phase diagrams. Implications of the topological behavior in finite quantum spin chains are discussed
Demonstrating Heisenberg-limited unambiguous phase estimation without adaptive measurements
International Nuclear Information System (INIS)
Higgins, B L; Wiseman, H M; Pryde, G J; Berry, D W; Bartlett, S D; Mitchell, M W
2009-01-01
We derive, and experimentally demonstrate, an interferometric scheme for unambiguous phase estimation with precision scaling at the Heisenberg limit that does not require adaptive measurements. That is, with no prior knowledge of the phase, we can obtain an estimate of the phase with a standard deviation that is only a small constant factor larger than the minimum physically allowed value. Our scheme resolves the phase ambiguity that exists when multiple passes through a phase shift, or NOON states, are used to obtain improved phase resolution. Like a recently introduced adaptive technique (Higgins et al 2007 Nature 450 393), our experiment uses multiple applications of the phase shift on single photons. By not requiring adaptive measurements, but rather using a predetermined measurement sequence, the present scheme is both conceptually simpler and significantly easier to implement. Additionally, we demonstrate a simplified adaptive scheme that also surpasses the standard quantum limit for single passes.
Optimal matrix product states for the Heisenberg spin chain
International Nuclear Information System (INIS)
Latorre, Jose I; Pico, Vicent
2009-01-01
We present some exact results for the optimal matrix product state (MPS) approximation to the ground state of the infinite isotropic Heisenberg spin-1/2 chain. Our approach is based on the systematic use of Schmidt decompositions to reduce the problem of approximating for the ground state of a spin chain to an analytical minimization. This allows one to show that results of standard simulations, e.g. density matrix renormalization group and infinite time evolving block decimation, do correspond to the result obtained by this minimization strategy and, thus, both methods deliver optimal MPS with the same energy but, otherwise, different properties. We also find that translational and rotational symmetries cannot be maintained simultaneously by the MPS ansatz of minimum energy and present explicit constructions for each case. Furthermore, we analyze symmetry restoration and quantify it to uncover new scaling relations. The method we propose can be extended to any translational invariant Hamiltonian
International Nuclear Information System (INIS)
Yan, T H; Li, Q; Xu, C; Pu, H Y; Chen, X D
2010-01-01
The design, realization and control technologies of a high-performance hybrid microvibration isolator for ultra-high-precision high-speed moving X/Y tables are presented in this paper—the novel isolator with integrated passive–active high level of damping. The passive damping was implemented using air-springs in both vertical and horizontal directions, with parallel linear motors in two directions to realize the active damping and the positioning functions. It is an actual hybrid isolation system because its air-spring can also be controlled through the pneumatic loop. The isolation servo system also has fast positioning capability via the feedforward compensation for the moving tables. Compared with the conventional filtered reference type control algorithms that rely on the assumption for the adaptive filter and the controlled system, in which the disturbance is estimated from the residual signal, the feedforward compensation here shows high effectiveness of vibration isolation and high-precision positioning performance for its platform. The performance of feedforward compensation has been enhanced via an efficient state estimation adaptive algorithm, the fast Kalman filter. Finally, experimental demonstration has been shown for the prototype system and the results have verified the effectiveness of the proposed isolator system design and the adaptive control algorithm for substantially enhanced damping of the platform system with the moving X/Y tables
International Nuclear Information System (INIS)
Jiang Jianjun; Liu Yongjun; Tang Fei; Yang Cuihong
2011-01-01
We investigated the properties of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain using the spin-wave theory. The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the model are calculated to be compared with the corresponding properties of the mixed spin (1, 1/2) chain for a range of α. The results demonstrate that all the properties show similar behaviours in the small α limit, so the properties of the mixed spin (1, 1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. -- Research Highlights: →The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain are calculated. →In the small α limit, the properties of the mixed spin (1,1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. →The spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain may be of interest for some real quasi-one-dimensional molecular magnetic materials.
CHOLESK, Diffusion Calculation with 2-D Source in X-Y or R-Z Geometry
International Nuclear Information System (INIS)
1988-01-01
1 - Description of problem or function: Solution of the diffusion equation with source in two-dimensional geometries x-y or r-z. 2 - Method of solution: The finite-element method of Ritz-Galerkin is applied
Influence of magnetic field on swap operation in Heisenberg XXZ model
Energy Technology Data Exchange (ETDEWEB)
Liu Jia [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Zhang Guofeng, E-mail: gf1978zhang@buaa.edu.c [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Chen Ziyu [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)
2009-05-01
Swap operation based on a two-qubit Heisenberg XXZ model under a uniform magnetic field in arbitrary direction and magnitude is investigated. It is shown that swap gate can be implemented on some conditions and its feasibility is established.
Influence of magnetic field on swap operation in Heisenberg XXZ model
International Nuclear Information System (INIS)
Liu Jia; Zhang Guofeng; Chen Ziyu
2009-01-01
Swap operation based on a two-qubit Heisenberg XXZ model under a uniform magnetic field in arbitrary direction and magnitude is investigated. It is shown that swap gate can be implemented on some conditions and its feasibility is established.
Uncertainty Einstein, Heisenberg, Bohr, and the struggle for the soul of science
Lindley, David
2007-01-01
The uncertainty in this delightful book refers to Heisenberg's Uncertainty Principle, an idea first postulated in 1927 by physicist Werner Heisenberg in his attempt to make sense out of the developing field of quantum mechanics. As Lindley so well explains it, the concept of uncertainty shook the philosophical underpinnings of science. It was Heisenberg's work that, to a great extent, kept Einstein from accepting quantum mechanics as a full explanation for physical reality. Similarly, it was the Uncertainty Principle that demonstrated the limits of scientific investigation: if Heisenberg is correct there are some aspects of the physical universe that are to remain beyond the reach of scientists. As he has done expertly in books like Boltzmann's Atom, Lindley brings to life a critical period in the history of science, explaining complex issues to the general reader, presenting the major players in an engaging fashion, delving into the process of scientific discovery and discussing the interaction between scien...
Topological term of the antiferromagnetic Heisenberg model in 2+1 dimension
International Nuclear Information System (INIS)
Wu Ke; Yu Lu; Zhu Chuanjie
1988-05-01
It is shown in this note that the two different ways of introducing the topological term in the discussion of the spin 1/2 antiferromagnetic Heisenberg model are identical to each other. (author). 12 refs
You err, Einstein.. Newton, Einstein, Heisenberg, and Feynman discuss quantum physics
International Nuclear Information System (INIS)
Fritzsch, Harald
2008-01-01
Harald Fritzsch and his star physicists Einstein, Heisenberg, and Feynman explain the central concept of nowadays physics, quantum mechanics, without it nothing goes in modern world. And the great Isaac newton puts the questions, which all would put
Wang, Dong; Huang, Aijun; Ming, Fei; Sun, Wenyang; Lu, Heping; Liu, Chengcheng; Ye, Liu
2017-06-01
The uncertainty principle provides a nontrivial bound to expose the precision for the outcome of the measurement on a pair of incompatible observables in a quantum system. Therefore, it is of essential importance for quantum precision measurement in the area of quantum information processing. Herein, we investigate quantum-memory-assisted entropic uncertainty relation (QMA-EUR) in a two-qubit Heisenberg \\boldsymbol{X}\\boldsymbol{Y}\\boldsymbol{Z} spin chain. Specifically, we observe the dynamics of QMA-EUR in a realistic model there are two correlated sites linked by a thermal entanglement in the spin chain with an inhomogeneous magnetic field. It turns out that the temperature, the external inhomogeneous magnetic field and the field inhomogeneity can lift the uncertainty of the measurement due to the reduction of the thermal entanglement, and explicitly higher temperature, stronger magnetic field or larger inhomogeneity of the field can result in inflation of the uncertainty. Besides, it is found that there exists distinct dynamical behaviors of the uncertainty for ferromagnetism \\boldsymbol{}≤ft(\\boldsymbol{J}\\boldsymbol{0}\\right) chains. Moreover, we also verify that the measuring uncertainty is dramatically anti-correlated with the purity of the bipartite spin system, the greater purity can result in the reduction of the measuring uncertainty, vice versa. Therefore, our observations might provide a better understanding of the dynamics of the entropic uncertainty in the Heisenberg spin chain, and thus shed light on quantum precision measurement in the framework of versatile systems, particularly solid states.
Adiabatic demagnetization of the antiferromagnetic spin-1/2 Heisenberg hexagonal cluster
International Nuclear Information System (INIS)
Deb, Moumita; Ghosh, Asim Kumar
2016-01-01
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 Cu_3WO_6.
Critical properties of the D=3 bond-mixed quantum Heisenberg ferromagnet
International Nuclear Information System (INIS)
Tsallis, C.; Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro); Stinchcombe, R.B.; Buck, B.
1983-01-01
Within a Migdal-Kadanoff-like real-space renormalisation group procedure critical properties of the quenched bond-mixed spin 1/2 Heisenberg ferromagnet in simple cubic lattice are treated. It is verified that it is possible, within a very simple framework, to obtain quite reliable results for the critical temperatures. In addition to that, a general method for renormalising arbitrary clusters of Heisenberg-coupled spins 1/2 is outlined. (Author) [pt
Criticality of the D=2 quantum Heisenberg ferromagnet with quenched random anisotropic
International Nuclear Information System (INIS)
Mariz, A.M.; Tsallis, C.
1985-01-01
The square-lattice spin 1/2 anisotropic Heisenberg ferromagnet is considered, with interactions whose symmetry can independently (quenched model) and randomly be of two competing types, namely the isotropic Heisenberg type and the Ising one. Within a real space renormalization group framework, a quite precise numerical calculation of the critical frontier is performed, and its main asymptotic behaviour are established. The relevant universality classes are also characterized, through the analysis of the correlation length critical exponent. (Author) [pt
Masuda, Nobuhisa; Sakagawa, Eiko; Ohya, Satoshi; Gotoh, Naomasa; Tsujimoto, Hideto; Nishino, Takeshi
2000-01-01
To find the exact substrate specificities of three species of tripartite efflux systems of Pseudomonas aeruginosa, MexAB-OprM, MexCD-OprJ, and MexXY-OprM, we constructed a series of isogenic mutants, each of which constitutively overproduced one of the three efflux systems and lacked the other two, and their isogenic mutants, which lacked all these systems. Comparison of the susceptibilities of the constructed mutants to 52 antimicrobial agents belonging to various groups suggested the following substrate specificities. All of the efflux systems extrude a wide variety of antimicrobial agent groups, i.e., quinolones, macrolides, tetracyclines, lincomycin, chloramphenicol, most penicillins (all but carbenicillin and sulbenicillin), most cephems (all but cefsulodin and ceftazidime), meropenem, and S-4661, but none of them extrude polymyxin B or imipenem. Extrusion of aminoglycosides is specific to MexXY-OprM, and extrusion of a group of the β-lactams, i.e., carbenicillin, sulbenicillin, ceftazidime, moxalactam, and aztreonam, is specific to MexAB-OprM. Moreover, MexAB-OprM and MexCD-OprJ extrude novobiocin, cefsulodin, and flomoxef, while MexXY-OprM does not. These substrate specificities are distinct from those reported previously. PMID:11083635
Deformation of products cut on AWJ x-y tables and its suppression
Hlaváč, L. M.; Hlaváčová, I. M.; Plančár, Š.; Krenický, T.; Geryk, V.
2018-02-01
The aim of this study is namely investigation of the abrasive water jet (AWJ) cutting of column pieces on commercial x-y cutting machines with AWJ. The shape deformation in curved and/or stepped parts of cutting trajectories caused by both the trailback (declination angle) and the taper (inclination of cut walls) can be calculated from submitted analytical model. Some of the results were compared with data measured on samples cut on two types of commercial tables. The main motivation of this investigation is determination of the percentage difference between predicted and real distortion of cutting product, i.e. accuracy of prepared analytical model. Subsequently, the possibility of reduction of the distortion can be studied through implementation of the theoretical model into the control systems of the cutting machines with the system for cutting head tilting. Despite some limitations of the used AWJ machines the comparison of calculated dimensions with the real ones shows very good correlation of model and experimental data lying within the range of measurement uncertainty. Results on special device demonstrated that the shape deformation in curved parts of the cutting trajectory can be substantially reduced through tilting of the cutting head.
Magnetic helices as metastable states of finite XY ferromagnetic chains: An analytical study
Popov, Alexander P.; Pini, Maria Gloria
2018-04-01
We investigated a simple but non trivial model, consisting of a chain of N classical XY spins with nearest neighbor ferromagnetic interaction, where each of the two end-point spins is assumed to be exchange-coupled to a fully-pinned fictitious spin. In the mean field approximation, the system might be representative of a soft ferromagnetic film sandwiched between two magnetically hard layers. We show that, while the ground state is ferromagnetic and collinear, the system can attain non-collinear metastable states in the form of magnetic helices. The helical solutions and their stability were studied analytically in the absence of an external magnetic field. There are four possible classes of solutions. Only one class is metastable, and its helical states contain an integer number of turns. Among the remaining unstable classes, there is a class of helices which contain an integer number of turns. Therefore, an integer number of turns in a helical configuration is a necessary, but not a sufficient, condition for metastability. These results may be useful to devise future applications of metastable magnetic helices as energy-storing elements.
International Nuclear Information System (INIS)
Delfin L, A.
1996-01-01
The purpose of this work is to solve the neutron transport equation in discrete-ordinates and X-Y geometry by developing and using the strong discontinuous and strong modified discontinuous nodal finite element schemes. The strong discontinuous and modified strong discontinuous nodal finite element schemes go from two to ten interpolation parameters per cell. They are describing giving a set D c and polynomial space S c corresponding for each scheme BDMO, RTO, BL, BDM1, HdV, BDFM1, RT1, BQ and BDM2. The solution is obtained solving the neutron transport equation moments for each nodal scheme by developing the basis functions defined by Pascal triangle and the Legendre moments giving in the polynomial space S c and, finally, looking for the non singularity of the resulting linear system. The linear system is numerically solved using a computer program for each scheme mentioned . It uses the LU method and forward and backward substitution and makes a partition of the domain in cells. The source terms and angular flux are calculated, using the directions and weights associated to the S N approximation and solving the angular flux moments to find the effective multiplication constant. The programs are written in Fortran language, using the dynamic allocation of memory to increase efficiently the available memory of the computing equipment. (Author)
Stapp's quantum dualism: The James/Heisenberg model of consciousness
International Nuclear Information System (INIS)
Noyes, H.P.
1994-01-01
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 along 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
Topological superconductivity in the extended Kitaev-Heisenberg model
Schmidt, Johann; Scherer, Daniel D.; Black-Schaffer, Annica M.
2018-01-01
We study superconducting pairing in the doped Kitaev-Heisenberg model by taking into account the recently proposed symmetric off-diagonal exchange Γ . By performing a mean-field analysis, we classify all possible superconducting phases in terms of symmetry, explicitly taking into account effects of spin-orbit coupling. Solving the resulting gap equations self-consistently, we map out a phase diagram that involves several topologically nontrivial states. For Γ breaking chiral phase with Chern number ±1 and a time-reversal symmetric nematic phase that breaks the rotational symmetry of the lattice. On the other hand, for Γ ≥0 we find a time-reversal symmetric phase that preserves all the lattice symmetries, thus yielding clearly distinguishable experimental signatures for all superconducting phases. Both of the time-reversal symmetric phases display a transition to a Z2 nontrivial phase at high doping levels. Finally, we also include a symmetry-allowed spin-orbit coupling kinetic energy and show that it destroys a tentative symmetry-protected topological order at lower doping levels. However, it can be used to tune the time-reversal symmetric phases into a Z2 nontrivial phase even at lower doping.
Reducing Uncertainty: Implementation of Heisenberg Principle to Measure Company Performance
Directory of Open Access Journals (Sweden)
Anna Svirina
2015-08-01
Full Text Available The paper addresses the problem of uncertainty reduction in estimation of future company performance, which is a result of wide range of enterprise's intangible assets probable efficiency. To reduce this problem, the paper suggests to use quantum economy principles, i.e. implementation of Heisenberg principle to measure efficiency and potential of intangible assets of the company. It is proposed that for intangibles it is not possible to estimate both potential and efficiency at a certain time point. To provide a proof for these thesis, the data on resources potential and efficiency from mid-Russian companies was evaluated within deterministic approach, which did not allow to evaluate probability of achieving certain resource efficiency, and quantum approach, which allowed to estimate the central point around which the probable efficiency of resources in concentrated. Visualization of these approaches was performed by means of LabView software. It was proven that for tangible assets performance estimation a deterministic approach should be used; while for intangible assets the quantum approach allows better quality of future performance prediction. On the basis of these findings we proposed the holistic approach towards estimation of company resource efficiency in order to reduce uncertainty in modeling company performance.
Emergent Criticality and Ricci Flow in a 2D Frustrated Heisenberg Model
Orth, Peter P.
2014-03-01
In most systems that exhibit order at low temperatures, the order occurs in the elementary degrees of freedom such as spin or charge. Prominent examples are magnetic or superconducting states of matter. In contrast, emergent order describes the phenomenon where composite objects exhibit longer range correlations. Such emergent order has been suspected to occur in a range of correlated materials. One specific example are spin systems with competing interactions, where long-range discrete order in the relative orientation of spins may occur. Interestingly, this order parameter may induce other phase transitions as is the case for the nematic transition in the iron pnictides. In this talk, we introduce and discuss a system with emergent Z6 symmetry, a two-dimensional frustrated Heisenberg antiferromagnet on the windmill lattice consisting of interpenetrating honeycomb and triangular lattices. The multiple spin stiffnesses can be captured in terms of a four-dimensional metric tensor, and the renormalization group flow of the stiffnesses is described by the Ricci flow of the metric tensor. The key result is a decoupling of an emergent collective degree of freedom given by the relative phase of spins on different sublattices. In particular, our results reveal a sequence of two Berezinskii-Kosterlitz-Thouless phase transitions that bracket a critical phase.
Phase transitions in two-dimensional uniformly frustrated XY models. II. General scheme
International Nuclear Information System (INIS)
Korshunov, S.E.
1986-01-01
For two-dimensional uniformly frustrated XY models the group of symmetry spontaneously broken in the ground state is a cross product of the group of two-dimensional rotations by some discrete group of finite order. Different possibilities of phase transitions in such systems are investigated. The transition to the Coulomb gas with noninteger charges is widely used when analyzing the properties of relevant topological excitations. The number of these excitations includes not only domain walls and traditional (integer) vortices, but also vortices with a fractional number of circulation quanta which are to be localized at bends and intersections of domain walls. The types of possible phase transitions prove to be dependent on their relative sequence: in the case the vanishing of domain wall free energy occurs earlier (at increasing temperature) than the dissociation of pairs of ordinary vortices, the second phase transition is to be associated with dissociation of pairs of fractional vortices. The general statements are illustrated with a number of examples
Craig's XY distribution and the statistics of Lagrangian power in two-dimensional turbulence
Bandi, Mahesh M.; Connaughton, Colm
2008-03-01
We examine the probability distribution function (PDF) of the energy injection rate (power) in numerical simulations of stationary two-dimensional (2D) turbulence in the Lagrangian frame. The simulation is designed to mimic an electromagnetically driven fluid layer, a well-documented system for generating 2D turbulence in the laboratory. In our simulations, the forcing and velocity fields are close to Gaussian. On the other hand, the measured PDF of injected power is very sharply peaked at zero, suggestive of a singularity there, with tails which are exponential but asymmetric. Large positive fluctuations are more probable than large negative fluctuations. It is this asymmetry of the tails which leads to a net positive mean value for the energy input despite the most probable value being zero. The main features of the power distribution are well described by Craig’s XY distribution for the PDF of the product of two correlated normal variables. We show that the power distribution should exhibit a logarithmic singularity at zero and decay exponentially for large absolute values of the power. We calculate the asymptotic behavior and express the asymmetry of the tails in terms of the correlation coefficient of the force and velocity. We compare the measured PDFs with the theoretical calculations and briefly discuss how the power PDF might change with other forcing mechanisms.
Thermodynamic limit of particle-hole form factors in the massless XXZ Heisenberg chain
Energy Technology Data Exchange (ETDEWEB)
Kitanine, N. [Univ. de Bourgogne (France). IMB, UMR 5584 du CNRS; Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M.; Terras, V. [ENS Lyon (France). UMR 5672 du CNRS, Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Inst., Moscow (Russian Federation)
2011-03-15
We study the thermodynamic limit of the particle-hole form factors of the XXZ Heisenberg chain in the massless regime. We show that, in this limit, such form factors decrease as an explicitly computed power-law in the system size. Moreover, the corresponding amplitudes can be obtained as a product of a ''smooth'' and a ''discrete'' part: the former depends continuously on the rapidities of the particles and holes, whereas the latter has an additional explicit dependence on the set of integer numbers that label each excited state in the associated logarithmic Bethe equations. We also show that special form factors corresponding to zero-energy excitations lying on the Fermi surface decrease as a power-law in the system size with the same critical exponents as in the longdistance asymptotic behavior of the related two-point correlation functions. The methods we develop in this article are rather general and can be applied to other massless integrable models associated to the six-vertex R-matrix and having determinant representations for their form factors. (orig.)
Nuclear spin relaxation in a spin-1/2 antiferromagnetic Heisenberg chain at high fields
International Nuclear Information System (INIS)
Lyo, S.K.
1981-01-01
The proton spin relaxation rate is calculated in the one-dimensional spin-1/2 Heisenberg antiferromagnet α-bis (N-methylsalicylaldiminato)-copper (II), α-CuNSal by using a fermion representation for magnons above the critical field where the magnon spectrum develops a gap. The one-magnon process which is dominant below the critical field is shown to be absent in the presence of a gap in contrast to a previous theory. Instead, we find that the three-magnon rate is large enough to explain the data at low fields. The two-magnon off-resonance damping which enters the expression for the three-magnon rate is calculated by solving the two-magnon scattering exactly, leading to a much smaller value of the rate than that predicted by the Born approximation. Also, in an unsuccessful attempt to resolve the discrepancy between the recently calculated two-magnon rate (dominant at high fields) and the data of α-CuNSal reported by Azevedo et al., we carry out the vertex correction for the spin-density correlation function by summing the RPA series as well as the exchange ladders for the polarization part. We find that, although the exchange enhancement is significantly large, it is nearly canceled out by the RPA correction, and the net effect of the vertex correction is small. This result agrees with the recent data of the similar spin-1/2 antiferromagnetic Heisenberg chain system CuSO 4 x5H 2 O reported by Groen et al. On the other hand, it disagrees with a recent calculation of the two-magnon rate based on a boson representation of spins. To resolve this discrepancy we examine the effect of the boson self-energy correction on the two-magnon rate. The boson spectral shift is found to be quite large in the region where the cited two-boson rate deviates from the two-fermion rate. As a result the two-boson rate is significantly reduced, leading to reasonable agreement with the two-fermion rate
Ret Finger Protein: An E3 Ubiquitin Ligase Juxtaposed to the XY Body in Meiosis
Directory of Open Access Journals (Sweden)
Isabelle Gillot
2009-01-01
Full Text Available During prophase I of male meiosis, the sex chromosomes form a compact structure called XY body that associates with the nuclear membrane of pachytene spermatocytes. Ret Finger Protein is a transcriptional repressor, able to interact with both nuclear matrix-associated proteins and double-stranded DNA. We report the precise and unique localization of Ret Finger Protein in pachytene spermatocytes, in which Ret Finger Protein takes place of lamin B1, between the XY body and the inner nuclear membrane. This localization of Ret Finger Protein does not seem to be associated with O-glycosylation or sumoylation. In addition, we demonstrate that Ret Finger Protein contains an E3 ubiquitin ligase activity. These observations lead to an attractive hypothesis in which Ret Finger Protein would be involved in the positioning and the attachment of XY body to the nuclear lamina of pachytene spermatocytes.
International Nuclear Information System (INIS)
Yin Shao-Ying; Song Jie; Xu Xue-Xin; Zhou Ke-Ya; Liu Shu-Tian; Liu Qing-Xin
2017-01-01
We investigate the prominent impacts of coupling strengths on the evolution of entanglement and quantum discord for a three-qubit system coupled to an XY spin-chain environment. In the case of a pure W state, more robust, even larger nonzero quantum correlations can be obtained by tailoring the coupling strengths between the qubits and the environment. For a mixed state consisting of the GHZ and W states, the dynamics of entanglement and quantum discord can characterize the critical point of quantum phase transition. Remarkably, a large nonzero quantum discord is generally retained, while the nonzero entanglement can only be obtained as the system-environment coupling satisfies certain conditions. We also find that the impact of each qubit’s coupling strength on the quantum correlation dynamics strongly depends on the variation schemes of the system-environment couplings. (paper)
DEFF Research Database (Denmark)
Gammelmark, Søren; Mølmer, Klaus
2011-01-01
We investigate the thermodynamics of a combined Dicke and Ising model that exhibits a rich phenomenology arising from the second-order and quantum phase transitions from the respective models. The partition function is calculated using mean-field theory, and the free energy is analyzed in detail...... to determine the complete phase diagram of the system. The analysis reveals both first- and second-order Dicke phase transitions into a super-radiant state, and the cavity mean field in this regime acts as an effective magnetic field, which restricts the Ising chain dynamics to parameter ranges away from...... the Ising phase transition. Physical systems with first-order phase transitions are natural candidates for metrology and calibration purposes, and we apply filter theory to show that the sensitivity of the physical system to temperature and external fields reaches the 1/N Heisenberg limit....
Shimada, Alisa; Nakano, Hiroki; Sakai, Tôru; Yoshimura, Kazuyoshi
2018-03-01
The S = 1/2 triangular-lattice Heisenberg antiferromagnet with distortion is investigated by the numerical-diagonalization method. The examined distortion type is √{3} × √{3} . We study the case when the distortion connects the undistorted triangular lattice and the dice lattice. For the intermediate phase reported previously in this system, we obtain results of the boundaries of the intermediate phase for a larger system than those in the previous report and examine the system size dependence of the boundaries in detail. We also report the specific heat of this system, which shows a marked peak structure related to the appearance of the intermediate state.
Method for solving quantum field theory in the Heisenberg picture
International Nuclear Information System (INIS)
Nakanishi, Noboru
2004-01-01
This paper is a review of the method for solving quantum field theory in the Heisenberg picture, developed by Abe and Nakanishi since 1991. Starting from field equations and canonical (anti) commutation relations, one sets up a (q-number) Cauchy problem for the totality of d-dimensional (anti) commutators between the fundamental fields, where d is the number of spacetime dimensions. Solving this Cauchy problem, one obtains the operator solution of the theory. Then one calculates all multiple commutators. A representation of the operator solution is obtained by constructing the set of all Wightman functions for the fundamental fields; the truncated Wightman functions are constructed so as to be consistent with all vacuum expectation values of the multiple commutators mentioned above and with the energy-positivity condition. By applying the method described above, exact solutions to various 2-dimensional gauge-theory and quantum-gravity models are found explicitly. The validity of these solutions is confirmed by comparing them with the conventional perturbation-theoretical results. However, a new anomalous feature, called the ''field-equation anomaly'', is often found to appear, and its perturbation-theoretical counterpart, unnoticed previously, is discussed. The conventional notion of an anomaly with respect to symmetry is reconsidered on the basis of the field-equation anomaly, and the derivation of the critical dimension in the BRS-formulated bosonic string theory is criticized. The method outlined above is applied to more realistic theories by expanding everything in powers of the relevant parameter, but this expansion is not equivalent to the conventional perturbative expansion. The new expansion is BRS-invariant at each order, in contrast to that in the conventional perturbation theory. Higher-order calculations are generally extremely laborious to perform explicitly. (author)
Dysgerminoma in a case of 46, XY pure gonadal dysgenesis (swyer syndrome: a case report
Directory of Open Access Journals (Sweden)
He Anguang
2011-09-01
Full Text Available Abstract Simple 46, XY gonadal dysgenesis syndrome, also called Swyer syndrome, is known as pure gonadal dysgenesis. Individuals with the syndrome are characterized by 46, XY karyotype and phenotypically female with female genital appearance, normal Müllerian structures and absent testicular tissue. The condition usually first becomes apparent in adolescence with delayed puberty and primary amenorrhea due to the gonads have no hormonal or reproductive potential. Herein, we report a case of dysgerminoma diagnosed in a dysgenetic gonad of a 21-year-old patient with Swyer syndrome.
Phase diagram of the Kondo-Heisenberg model on honeycomb lattice with geometrical frustration
Li, Huan; Song, Hai-Feng; Liu, Yu
2016-11-01
We calculated the phase diagram of the Kondo-Heisenberg model on a two-dimensional honeycomb lattice with both nearest-neighbor and next-nearest-neighbor antiferromagnetic spin exchanges, to investigate the interplay between RKKY and Kondo interactions in the presence of magnetic frustration. Within a mean-field decoupling technology in slave-fermion representation, we derived the zero-temperature phase diagram as a function of Kondo coupling J k and frustration strength Q. The geometrical frustration can destroy the magnetic order, driving the original antiferromagnetic (AF) phase to non-magnetic valence bond solids (VBS). In addition, we found two distinct VBS. As J k is increased, a phase transition from AF to Kondo paramagnetic (KP) phase occurs, without the intermediate phase coexisting AF order with Kondo screening found in square lattice systems. In the KP phase, the enhancement of frustration weakens the Kondo screening effect, resulting in a phase transition from KP to VBS. We also found a process to recover the AF order from VBS by increasing J k in a wide range of frustration strength. Our work may provide predictions for future experimental observation of new processes of quantum phase transitions in frustrated heavy-fermion compounds.
Quantum entanglement and criticality of the antiferromagnetic Heisenberg model in an external field
International Nuclear Information System (INIS)
Liu Guanghua; Li Ruoyan; Tian Guangshan
2012-01-01
By Lanczos exact diagonalization and the infinite time-evolving block decimation (iTEBD) technique, the two-site entanglement as well as the bipartite entanglement, the ground state energy, the nearest-neighbor correlations, and the magnetization in the antiferromagnetic Heisenberg (AFH) model under an external field are investigated. With increasing external field, the small size system shows some distinct upward magnetization stairsteps, accompanied synchronously with some downward two-site entanglement stairsteps. In the thermodynamic limit, the two-site entanglement, as well as the bipartite entanglement, the ground state energy, the nearest-neighbor correlations, and the magnetization are calculated, and the critical magnetic field h c = 2.0 is determined exactly. Our numerical results show that the quantum entanglement is sensitive to the subtle changing of the ground state, and can be used to describe the magnetization and quantum phase transition. Based on the discontinuous behavior of the first-order derivative of the entanglement entropy and fidelity per site, we think that the quantum phase transition in this model should belong to the second-order category. Furthermore, in the magnon existence region (h < 2.0), a logarithmically divergent behavior of block entanglement which can be described by a free bosonic field theory is observed, and the central charge c is determined to be 1. (paper)
The q-deformed SU(2) Heisenberg model in 3-dimensions
International Nuclear Information System (INIS)
Lu Zhongyi; Yan Hong.
1991-07-01
A q-deformed SU(2) Heisenberg (3-dimensional) spin model is set up, and the q-deformed spin-wave solution is obtained through the q-analogous Holstein-Primakoff transformation. The result is given for small γ = ln q, which is the quantity characterizing the nonlinearity of the Hamiltonian. A mean-field treatment is arranged to preserved (at least some of) the nonlinearity, and the ordinary ferromagnet ground state is shown as the exact ground state of the new system. Interesting results are obtained for this nonlinear model: (i) There is an energy gap between the ground state and the first excited one, thus the ground state is stable under small perturbation of the background; (ii) the specific heat per volume is modified by a small term proportional to the 1/2-th power of temperature and the square of γ, which is qualitatively different from the conventional model, and (iii) the magnetization M(T) is modified by a factor that depends on γ. (author). 16 refs
Weakly coupled S=1/2 quantum Heisenberg antiferromagnetic chains in an effective staggered field
International Nuclear Information System (INIS)
Sato, Masahiro; Oshikawa, Masaki
2002-01-01
We study weakly coupled S=1/2 quantum Heisenberg antiferromagnetic chains in an effective staggered field. Applying mean-field (MF) theory, spin-wave theory and chain MF (CMF) theory, we can see analytically some effects of the staggered field in this higher dimensional spin system. In particular, when the staggered field and the inter-chain inter-action compete with each other, we conjecture from the MF theory that a nontrivial phase is present. The spin wave theory predicts that the behavior of the gaps induced by a staggered field is different between the competitive case and the non-competitive case. When the inter-chain interactions are weak enough, we can improve the MF phase diagram by using CMF theory and the analytical results of field theories. The ordered phase region predicted by the CMF theory is fairly smaller than one of the MF theory. Cu-benzoate, CuCl 2 · 2DMSO (dimethylsulphoxide), BaCu 2 (Si 1-x Ge x ) 2 O 7 , etc., could be described by our model in enough low temperature. (author)
International Nuclear Information System (INIS)
Mayhall, Nicholas J.; Head-Gordon, Martin
2014-01-01
We highlight a simple strategy for computing the magnetic coupling constants, J, for a complex containing two multiradical centers. On the assumption that the system follows Heisenberg Hamiltonian physics, J is obtained from a spin-flip electronic structure calculation where only a single electron is excited (and spin-flipped), from the single reference with maximum S ^ z , M, to the M − 1 manifold, regardless of the number of unpaired electrons, 2M, on the radical centers. In an active space picture involving 2M orbitals, only one β electron is required, together with only one α hole. While this observation is extremely simple, the reduction in the number of essential configurations from exponential in M to only linear provides dramatic computational benefits. This (M, M − 1) strategy for evaluating J is an unambiguous, spin-pure, wave function theory counterpart of the various projected broken symmetry density functional theory schemes, and likewise gives explicit energies for each possible spin-state that enable evaluation of properties. The approach is illustrated on five complexes with varying numbers of unpaired electrons, for which one spin-flip calculations are used to compute J. Some implications for further development of spin-flip methods are discussed
Persistence of the gapless spin liquid in the breathing kagome Heisenberg antiferromagnet
Iqbal, Yasir; Poilblanc, Didier; Thomale, Ronny; Becca, Federico
2018-03-01
The nature of the ground state of the spin S =1 /2 Heisenberg antiferromagnet on the kagome lattice with breathing anisotropy (i.e., with different superexchange couplings J▵ and J▿ within elementary up- and down-pointing triangles) is investigated within the framework of Gutzwiller projected fermionic wave functions and Monte Carlo methods. We analyze the stability of the U(1 ) Dirac spin liquid with respect to the presence of fermionic pairing that leads to a gapped Z2 spin liquid. For several values of the ratio J▿/J▵ , the size scaling of the energy gain due to the pairing fields and the variational parameters are reported. Our results show that the energy gain of the gapped spin liquid with respect to the gapless state either vanishes for large enough system size or scales to zero in the thermodynamic limit. Similarly, the optimized pairing amplitudes (responsible for opening the spin gap) are shown to vanish in the thermodynamic limit. Our outcome is corroborated by the application of one and two Lanczos steps to the gapless and gapped wave functions, for which no energy gain of the gapped state is detected when improving the quality of the variational states. Finally, we discuss the competition with the "simplex" Z2 resonating-valence-bond spin liquid, valence-bond crystal, and nematic states in the strongly anisotropic regime, i.e., J▿≪J▵ .
An analogue of the Heisenberg uncertainty relation in prequantum classical field theory
Energy Technology Data Exchange (ETDEWEB)
Khrennikov, Andrei, E-mail: Andrei.Khrennikov@vxu.s [International Center for Mathematical Modelling in Physics and Cognitive Sciences, University of Vaexjoe, Vaexjoe (Sweden) and Institute of Information Security, Russian State University for Humanities, Moscow (Russian Federation)
2010-02-01
Prequantum classical statistical field theory (PCSFT) is a model that provides the possibility of representing averages of quantum observables, including correlations of observables on subsystems of a composite system, as averages with respect to fluctuations of classical random fields. PCSFT is a classical model of wave type. For example, 'electron' is described by electronic field. In contrast to quantum mechanics (QM), this field is a real physical field and not a field of probabilities. An important point is that the prequantum field of , for example, an electron contains the irreducible contribution of the background field vacuum fluctuations. In principle, the traditional QM-formalism can be considered as a special regularization procedure: subtraction of averages with respect to vacuum fluctuations. In this paper, we derive a classical analogue of the Heisenberg-Robertson inequality for dispersions of functionals of classical (prequantum) fields. The PCSFT Robertson-like inequality provides a restriction on the product of classical dispersions. However, this restriction is not so rigid as in QM.
An analogue of the Heisenberg uncertainty relation in prequantum classical field theory
International Nuclear Information System (INIS)
Khrennikov, Andrei
2010-01-01
Prequantum classical statistical field theory (PCSFT) is a model that provides the possibility of representing averages of quantum observables, including correlations of observables on subsystems of a composite system, as averages with respect to fluctuations of classical random fields. PCSFT is a classical model of wave type. For example, 'electron' is described by electronic field. In contrast to quantum mechanics (QM), this field is a real physical field and not a field of probabilities. An important point is that the prequantum field of , for example, an electron contains the irreducible contribution of the background field vacuum fluctuations. In principle, the traditional QM-formalism can be considered as a special regularization procedure: subtraction of averages with respect to vacuum fluctuations. In this paper, we derive a classical analogue of the Heisenberg-Robertson inequality for dispersions of functionals of classical (prequantum) fields. The PCSFT Robertson-like inequality provides a restriction on the product of classical dispersions. However, this restriction is not so rigid as in QM.
Geon-type solutions of the non-linear Heisenberg-Klein-Gordon equation
International Nuclear Information System (INIS)
Mielke, E.W.; Scherzer, R.
1980-10-01
As a model for a ''unitary'' field theory of extended particles we consider the non-linear Klein-Gordon equation - associated with a ''squared'' Heisenberg-Pauli-Weyl non-linear spinor equation - coupled to strong gravity. Using a stationary spherical ansatz for the complex scalar field as well as for the background metric generated via Einstein's field equation, we are able to study the effects of the scalar self-interaction as well as of the classical tensor forces. By numerical integration we obtain a continuous spectrum of localized, gravitational solitons resembling the geons previously constructed for the Einstein-Maxwell system by Wheeler. A self-generated curvature potential originating from the curved background partially confines the Schroedinger type wave functions within the ''scalar geon''. For zero angular momentum states and normalized scalar charge the spectrum for the total gravitational energy of these solitons exhibits a branching with respect to the number of nodes appearing in the radial part of the scalar field. Preliminary studies for higher values of the corresponding ''principal quantum number'' reveal that a kind of fine splitting of the energy levels occurs, which may indicate a rich, particle-like structure of these ''quantized geons''. (author)
International Nuclear Information System (INIS)
Cregg, P J; Murphy, K; Garcia-Palacios, J L; Svedlindh, P
2008-01-01
Interest in molecular magnets continues to grow, offering a link between the atomic and nanoscale properties. The classical Heisenberg model has been effective in modelling exchange interactions in such systems. In this, the magnetization and susceptibility are calculated through the partition function, where the Hamiltonian contains both Zeeman and exchange energy. For an ensemble of N spins, this requires integrals in 2N dimensions. For two, three and four spin nearest-neighbour chains these integrals reduce to sums of known functions. For the case of the three and four spin chains, the sums are equivalent to results of Joyce. Expanding these sums, the effect of the exchange on the linear susceptibility appears as Langevin functions with exchange term arguments. These expressions are generalized here to describe an N spin nearest-neighbour chain, where the exchange between each pair of nearest neighbours is different and arbitrary. For a common exchange constant, this reduces to the result of Fisher. The high-temperature expansion of the Langevin functions for the different exchange constants leads to agreement with the appropriate high-temperature quantum formula of Schmidt et al, when the spin number is large. Simulations are presented for open linear chains of three, four and five spins with up to four different exchange constants, illustrating how the exchange constants can be retrieved successfully
Spinon confinement in a quasi-one-dimensional XXZ Heisenberg antiferromagnet
Lake, Bella; Bera, Anup K.; Essler, Fabian H. L.; Vanderstraeten, Laurens; Hubig, Claudius; Schollwock, Ulrich; Islam, A. T. M. Nazmul; Schneidewind, Astrid; Quintero-Castro, Diana L.
Half-integer spin Heisenberg chains constitute a key paradigm for quantum number fractionalization: flipping a spin creates a minimum of two elementary spinon excitations. These have been observed in numerous experiments. We report on inelastic neutron scattering experiments on the quasi-one-dimensional anisotropic spin-1/2 Heisenberg antiferromagnet SrCo2V2O8. These reveal a mechanism for temperature-induced spinon confinement, manifesting itself in the formation of sequences of spinon bound states. A theoretical description of this effect is achieved by a combination of analytical and numerical methods.
Emergent Power-Law Phase in the 2D Heisenberg Windmill Antiferromagnet: A Computational Experiment
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.
New Topological Configurations in the Continuous Heisenberg Spin Chain: Lower Bound for the Energy
Directory of Open Access Journals (Sweden)
Rossen Dandoloff
2015-01-01
Full Text Available In order to study the spin configurations of the classical one-dimensional Heisenberg model, we map the normalized unit vector, representing the spin, on a space curve. We show that the total chirality of the configuration is a conserved quantity. If, for example, one end of the space curve is rotated by an angle of 2π relative to the other, the Frenet frame traces out a noncontractible loop in SO(3 and this defines a new class of topological spin configurations for the Heisenberg model.
Spinon decay in the spin-1/2 Heisenberg chain with weak next nearest neighbour exchange
International Nuclear Information System (INIS)
Groha, Stefan; Essler, Fabian H L
2017-01-01
Integrable models support elementary excitations with infinite lifetimes. In the spin-1/2 Heisenberg chain these are known as spinons. We consider the stability of spinons when a weak integrability breaking perturbation is added to the Heisenberg chain in a magnetic field. We focus on the case where the perturbation is a next nearest neighbour exchange interaction. We calculate the spinon decay rate in leading order in perturbation theory using methods of integrability and identify the dominant decay channels. The decay rate is found to be small, which indicates that spinons remain well-defined excitations even though integrability is broken. (paper)
Heisenberg-limited interferometry with pair coherent states and parity measurements
International Nuclear Information System (INIS)
Gerry, Christopher C.; Mimih, Jihane
2010-01-01
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.
Critical behavior of the quantum spin- {1}/{2} anisotropic Heisenberg model
Sousa, J. Ricardo de
A two-step renormalization group approach - a decimation followed by an effective field renormalization group (EFRG) - is proposed in this work to study the critical behavior of the quantum spin- {1}/{2} anisotropic Heisenberg model. The new method is illustrated by employing approximations in which clusters with one, two and three spins are used. The values of the critical parameter and critical exponent, in two- and three-dimensional lattices, for the Ising and isotropic Heisenberg limits are calculated and compared with other renormalization group approaches and exact (or series) results.
International Nuclear Information System (INIS)
Ding Qing
2007-01-01
We prove that the integrable-nonintegrable discrete nonlinear Schroedinger equation (AL-DNLS) introduced by Cai, Bishop and Gronbech-Jensen (Phys. Rev. Lett. 72 591(1994)) is the discrete gauge equivalent to an integrable-nonintegrable discrete Heisenberg model from the geometric point of view. Then we study whether the transmission and bifurcation properties of the AL-DNLS equation are preserved under the action of discrete gauge transformations. Our results reveal that the transmission property of the AL-DNLS equation is completely preserved and the bifurcation property is conditionally preserved to those of the integrable-nonintegrable discrete Heisenberg model
Partition functions of classical Heisenberg spin chains with arbitrary and different exchange
International Nuclear Information System (INIS)
Cregg, P J; GarcIa-Palacios, J L; Svedlindh, P
2008-01-01
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
Criticality of the D=2 bond-dilute anisotropic Heisenberg ferromagnet
International Nuclear Information System (INIS)
Mariz, A.M.; Tsallis, C.; Caride, A.O.
1984-01-01
The critical frontier and critical exponents associated with the quenched bond-dilute quantum anisotropic spin 1/2 Heisenberg ferromagnet in square lattice are described. To perform the calculations, an approximate real-space renormalization-group framework recently developed by some of us for the pure model (and analysed with some detail) is extended. Whenever comparison with available exact results is possible, the agreement is either perfect or quite satisfactory. Some effort has been dedicated to extract the main asymptotic behaviours of the critical frontier. Also several interesting quantum effects appearing in the composition laws of (Heisenberg) bond arrays are exhibited. (Author) [pt
A silicon integrated micro nano-positioning XY-stage for nano-manipulation
International Nuclear Information System (INIS)
Sun Lining; Wang Jiachou; Rong Weibin; Li Xinxin; Bao Haifei
2008-01-01
An integrated micro XY-stage with a 2 × 2 mm 2 movable table is designed and fabricated for application in nanometer-scale operation and nanometric positioning precision. The device integrates the functions of both actuating and sensing in a monolithic chip and is mainly composed of a silicon-based XY-stage, comb-drive actuator and a displacement sensor, which are developed by using double-sided bulk-micromachining technology. The high-aspect-ratio comb-driven XY-stage is achieved by deep reactive ion etching (DRIE) on both sides of the wafer. The displacement sensor is formed on four vertical sidewall surface piezoresistors with a full Wheatstone bridge circuit, where a novel fabrication process of a vertical sidewall surface piezoresistor is proposed. Comprehensive design and analysis of the comb actuator, the piezoresistive displacement sensor and the XY-stage are given in full detail, and the experimental results verify the design and fabrication of the device. The final realization of the device shows that the sensitivity of the fabricated piezoresistive sensors is better than 1.17 mV µm −1 without amplification, and the linearity is better than 0.814%. Under 28.5 V driving voltage, a ±10 µm single-axis displacement is measured without crosstalk and the resonant frequency is measured at 983 Hz in air
Primary amenorrhoea: Swyer syndrome in a woman with pure 46,XY ...
African Journals Online (AJOL)
patient who presented with primary amenorrhoea and primary infertility. She was a 24-year-old phenotypically female patient with a delayed diagnosis of Swyer syndrome. S Afr J Obstet Gynaecol 2015;21(1):16-17. DOI:10.7196/SAJOG.891. Primary amenorrhoea: Swyer syndrome in a woman with pure. 46,XY gonadal ...
A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans.
Chen, Xu; Guo, Tengfei; Hou, Yubin; Zhang, Jing; Meng, Wenjie; Lu, Qingyou
2017-01-01
A new scan-head structure for the scanning tunneling microscope (STM) is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans) coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan). They are fixed at one end (called common end). A hollow tantalum shaft is coaxially housed in the XY -scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.
A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans
Directory of Open Access Journals (Sweden)
Xu Chen
2017-01-01
Full Text Available A new scan-head structure for the scanning tunneling microscope (STM is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan. They are fixed at one end (called common end. A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.
Experimental Insights into Ground-State Selection of Quantum XY Pyrochlores
Hallas, Alannah M.; Gaudet, Jonathan; Gaulin, Bruce D.
2018-03-01
Extensive experimental investigations of the magnetic structures and excitations in the XY pyrochlores have been carried out over the past decade. Three families of XY pyrochlores have emerged: Yb2B2O7, Er2B2O7, and, most recently, [Formula: see text]Co2F7. In each case, the magnetic cation (either Yb, Er, or Co) exhibits XY anisotropy within the local pyrochlore coordinates, a consequence of crystal field effects. Materials in these families display rich phase behavior and are candidates for exotic ground states, such as quantum spin ice, and exotic ground-state selection via order-by-disorder mechanisms. In this review, we present an experimental summary of the ground-state properties of the XY pyrochlores, including evidence that they are strongly influenced by phase competition. We empirically demonstrate the signatures for phase competition in a frustrated magnet: multiple heat capacity anomalies, suppressed TN or TC, sample- and pressure-dependent ground states, and unconventional spin dynamics.
Spontaneous magnetization of quantum XY-chain from finite chain form-factor
International Nuclear Information System (INIS)
Iorgov, N.Z.
2010-01-01
Using the explicit factorized formulas for matrix elements (form-factors) of the spin operators between vectors of the Hamiltonian of a finite quantum XY-chain in a transverse field, the spontaneous magnetization for σ x and σ y is re-derived in a simple way.
Asymptotics of Toeplitz determinants and the emptiness formation probability for the XY spin chain
International Nuclear Information System (INIS)
Franchini, Fabio; Abanov, Alexander G
2005-01-01
We study an asymptotic behaviour of a special correlator known as the emptiness formation probability (EFP) for the one-dimensional anisotropic XY spin-1/2 chain in a transverse magnetic field. This correlator is essentially the probability of formation of a ferromagnetic string of length n in the antiferromagnetic ground state of the chain and plays an important role in the theory of integrable models. For the XY spin chain, the correlator can be expressed as the determinant of a Toeplitz matrix and its asymptotical behaviours for n → ∞ throughout the phase diagram are obtained using known theorems and conjectures on Toeplitz determinants. We find that the decay is exponential everywhere in the phase diagram of the XY model except on the critical lines, i.e. where the spectrum is gapless. In these cases, a power-law prefactor with a universal exponent arises in addition to an exponential or Gaussian decay. The latter Gaussian behaviour holds on the critical line corresponding to the isotropic XY model, while at the critical value of the magnetic field the EFP decays exponentially. At small anisotropy one has a crossover from the Gaussian to the exponential behaviour. We study this crossover using the bosonization approach
Improved variational estimates for the mass gap in the 2-dimensional XY-model
International Nuclear Information System (INIS)
Patkos, A.; Hari Dass, N.D.
1982-07-01
The variational estimate obtained recently for the mass gap of the 2-dimensional XY-model is improved by extending the treatment to higher powers of the transfer operator. The relativistic dispersion relation for single particle states of low momentum is also verified. (Auth.)
Increased high-density lipoprotein cholesterol levels in mice with XX versus XY sex chromosomes.
Link, Jenny C; Chen, Xuqi; Prien, Christopher; Borja, Mark S; Hammerson, Bradley; Oda, Michael N; Arnold, Arthur P; Reue, Karen
2015-08-01
The molecular mechanisms underlying sex differences in dyslipidemia are poorly understood. We aimed to distinguish genetic and hormonal regulators of sex differences in plasma lipid levels. We assessed the role of gonadal hormones and sex chromosome complement on lipid levels using the four core genotypes mouse model (XX females, XX males, XY females, and XY males). In gonadally intact mice fed a chow diet, lipid levels were influenced by both male-female gonadal sex and XX-XY chromosome complement. Gonadectomy of adult mice revealed that the male-female differences are dependent on acute effects of gonadal hormones. In both intact and gonadectomized animals, XX mice had higher HDL cholesterol (HDL-C) levels than XY mice, regardless of male-female sex. Feeding a cholesterol-enriched diet produced distinct patterns of sex differences in lipid levels compared with a chow diet, revealing the interaction of gonadal and chromosomal sex with diet. Notably, under all dietary and gonadal conditions, HDL-C levels were higher in mice with 2 X chromosomes compared with mice with an X and Y chromosome. By generating mice with XX, XY, and XXY chromosome complements, we determined that the presence of 2 X chromosomes, and not the absence of the Y chromosome, influences HDL-C concentration. We demonstrate that having 2 X chromosomes versus an X and Y chromosome complement drives sex differences in HDL-C. It is conceivable that increased expression of genes escaping X-inactivation in XX mice regulates downstream processes to establish sexual dimorphism in plasma lipid levels. © 2015 American Heart Association, Inc.
Evaluation of MotionSim XY/4D for patient specific QA of respiratory gated treatment for lung cancer
International Nuclear Information System (INIS)
Wen, C.; Ackerly, T.; Lancaster, C.; Bailey, N.
2011-01-01
Full text: A commercial system-MotionSim XY/4D(TM) capable of simulating two-dimensional tumour motion and measuring planar dose with diode-matrix was evaluated at the Alfred Hospital, for establishing patient-specific QA programme of respiratory gated treatment of lung cancer. This study presents the investigation of accuracies, limitations and the practical aspects of that system. Planar doses generated on iPlan-TM by mapping clinical beams to a scanned-in water phantom were measured by MotionSim XY/4D-TM with 5 cm water equivalent build-up at normal incidence. The gated delivery using ExacTrac-TM through tracking infrared markers simulating external respiration surrogate was measured simultaneously with Gaf-ChromicR RTQA2 film and MapCHECK 2TM . Dose maps of both non-gated and gated beams with 30% duty cycle were compared with both film and diodes measurements. Differences in dose distribution were analysed with built-in tools in MapCHECK2 TM and the effect of residual motion within the beamenabled window was then assessed. Preliminary results indicate that difference between Gafchromic film and MapCHECK2 measurements of same beam was ignorable. Gated dose delivery to a target at 9 mm maximum motion was in good agreement with planned dose. Complement to measurements suggested in AAPM Report No.9 I I, this QA device can detect any random error and assess the magnitude of residual target motion through analysing differences between planned and delivered doses as gamma function. Although some user-friendliness aspects could be improved, it meets its specification and can be used for routine clinical QA purposes provided calibrations were performed and procedures were followed.
From four- to two-channel Kondo effect in junctions of XY spin chains
Directory of Open Access Journals (Sweden)
Domenico Giuliano
2016-08-01
Full Text Available We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.
From four- to two-channel Kondo effect in junctions of XY spin chains
International Nuclear Information System (INIS)
Giuliano, Domenico; Sodano, Pasquale; Tagliacozzo, Arturo; Trombettoni, Andrea
2016-01-01
We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair) channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.
From four- to two-channel Kondo effect in junctions of XY spin chains
Energy Technology Data Exchange (ETDEWEB)
Giuliano, Domenico, E-mail: domenico.giuliano@fis.unical.it [Dipartimento di Fisica, Università della Calabria, Arcavacata di Rende I-87036, Cosenza (Italy); INFN, Gruppo collegato di Cosenza, Arcavacata di Rende I-87036, Cosenza (Italy); Sodano, Pasquale, E-mail: pasquale.sodano02@gmail.com [International Institute of Physics, Universidade Federal do Rio Grande do Norte, 59078-400 Natal, RN (Brazil); Departemento de Física Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Tagliacozzo, Arturo, E-mail: arturo.tagliacozzo@na.infn.it [INFN, Gruppo collegato di Cosenza, Arcavacata di Rende I-87036, Cosenza (Italy); Dipartimento di Fisica, Università di Napoli “Federico II”, Monte S. Angelo-Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, Monte S. Angelo-Via Cintia, I-80126 Napoli (Italy); Trombettoni, Andrea, E-mail: andreatr@sissa.it [CNR-IOM DEMOCRITOS Simulation Center, Via Bonomea 265, I-34136 Trieste (Italy); SISSA and INFN, Sezione di Trieste, Via Bonomea 265, I-34136 Trieste (Italy)
2016-08-15
We consider the Kondo effect in Y-junctions of anisotropic XY models in an applied magnetic field along the critical lines characterized by a gapless excitation spectrum. We find that, while the boundary interaction Hamiltonian describing the junction can be recasted in the form of a four-channel, spin-1/2 antiferromagnetic Kondo Hamiltonian, the number of channels effectively participating in the Kondo effect depends on the chain parameters, as well as on the boundary couplings at the junction. The system evolves from an effective four-channel topological Kondo effect for a junction of XX-chains with symmetric boundary couplings into a two-channel one at a junction of three quantum critical Ising chains. The effective number of Kondo channels depends on the properties of the boundary and of the bulk. The XX-line is a “critical” line, where a four-channel topological Kondo effect can be recovered by fine-tuning the boundary parameter, while along the line in parameter space connecting the XX-line and the critical Ising point the junction is effectively equivalent to a two-channel topological Kondo Hamiltonian. Using a renormalization group approach, we determine the flow of the boundary couplings, which allows us to define and estimate the critical couplings and Kondo temperatures of the different Kondo (pair) channels. Finally, we study the local transverse magnetization in the center of the Y-junction, eventually arguing that it provides an effective tool to monitor the onset of the two-channel Kondo effect.
On the Quantum Inverse problem for the continuous Heisenberg spin chain with axial anisotropy
International Nuclear Information System (INIS)
Roy Chowdhury, A.; Chanda, P.K.
1986-06-01
We have considered the Quantum Inverse problem for the continuous form of Heisenberg spin chain with anisotropy. The form of quantum R-matrix, the commutation rules for the scattering data, and the explicit structure of the excitation spectrum are obtained. (author)
Deformed Heisenberg algebra and fractional spin field in 2+1 dimensions
International Nuclear Information System (INIS)
Plyushchay, M.S.
1993-09-01
With the help of the deformed Heisenberg algebra involving the Klein operator, we construct the minimal set of linear differential equations for the (2+1)-dimensional relativistic field with arbitrary fractional spin, whose value is defined by the deformation parameters. (author). 23 refs
A thermodynamic approximation of the groundstate of antiferromagnetic Heisenberg spin-1/2 lattices
Tielen, G.I.; Iske, P.L.; Caspers, W.J.; Caspers, W.J.
1991-01-01
The exact ground state of finite Heisenberg spin−1/2 lattices isstudied. The coefficients of the so-called Ising configurations contributing to the ground state are approximated by Boltzmann-like expressions. These expressions contain a parameter that may be related to an inverse temperature.
Odd number of coupled antiferromagnetic anisotropic Heisenberg chains: Spin wave theory
International Nuclear Information System (INIS)
Benyoussef, A.
1996-10-01
The effect of the chain and perpendicular anisotropies on the energy gap for odd number of coupled quantum spin-1/2 antiferromagnetic anisotropic Heisenberg chains is investigated using a spin wave theory. The energy gap opens above a critical anisotropic value. The known results of the isotropic case have been obtained. (author). 11 refs, 4 figs
The 2-dimensional O(4) symmetric Heisenberg ferromagnet in terms of rotation invariant variables
International Nuclear Information System (INIS)
Holtkamp, A.
1981-09-01
After introduction of rotation invariant auxiliary variables, the integration over all rotation variant variables (spins) in the 0(4) symmetric two-dimensional Heisenberg ferromagnet can be performed. The resulting new Hamiltonian involves a sum over closed loops. It is complex and invariant under U(1) gauge transformations. Ruehl's boson representation is used to derive the result. (orig.)
The existence of a stable noncollinear phase in a Heisenberg model with complex structure
Energy Technology Data Exchange (ETDEWEB)
Shopova, Diana V.; Boyadjiev, Todor L
2003-05-19
We have analyzed the properties of a noncollinear magnetic phase obtained in the mean-field analysis of the model of two coupled Heisenberg subsystems. The domain of its existence and stability is narrow and depends on the ratio between the averaged over nearest neighbours microscopic exchange parameters.
Criticality of the anisotropic quantum Heisenberg model on a simple cubic lattice
International Nuclear Information System (INIS)
Mariz, A.M.; Santos, R.M.Z. dos; Tsallis, C.; Santos, R.R. dos.
1984-01-01
Within a Real Space Renormalization group framework, the criticality (phase diagram, and critical thermal and crossover exponents) of the spin 1/2 - anisotropic quantum Heisenberg ferromagnet on a simple cubic lattice is studied. The results obtained are in satisfactory agreement with known results whenever available. (Author) [pt
Criticality of the anisotropic quantum Heisenberg model on a simple cubic lattice
International Nuclear Information System (INIS)
Mariz, A.M.; Tsallis, C.; Santos, R.M.Z. dos; Santos, Raimundo R. dos.
1984-11-01
Within a Real Space Renormalization Group Framework, the criticality (phase diagram, and critical thermal and crossover exponents) of the spin 1/2 - anisotropic quantum Heisenberg ferromagnet on a simple cubic lattice is studied. The results obtained are in antisfactory agreement with known results whenever available. (Author) [pt
Merino, Jaime; Ralko, Arnaud
2018-05-01
Motivated by the rich physics of honeycomb magnetic materials, we obtain the phase diagram and analyze magnetic properties of the spin-1 /2 and spin-1 J1-J2-J3 Heisenberg model on the honeycomb lattice. Based on the SU(2) and SU(3) symmetry representations of the Schwinger boson approach, which treats disordered spin liquids and magnetically ordered phases on an equal footing, we obtain the complete phase diagrams in the (J2,J3) plane. This is achieved using a fully unrestricted approach which does not assume any pre-defined Ansätze. For S =1 /2 , we find a quantum spin liquid (QSL) stabilized between the Néel, spiral, and collinear antiferromagnetic phases in agreement with previous theoretical work. However, by increasing S from 1 /2 to 1, the QSL is quickly destroyed due to the weakening of quantum fluctuations indicating that the model already behaves as a quasiclassical system. The dynamical structure factors and temperature dependence of the magnetic susceptibility are obtained in order to characterize all phases in the phase diagrams. Moreover, motivated by the relevance of the single-ion anisotropy, D , to various S =1 honeycomb compounds, we have analyzed the destruction of magnetic order based on an SU(3) representation of the Schwinger bosons. Our analysis provides a unified understanding of the magnetic properties of honeycomb materials realizing the J1-J2-J3 Heisenberg model from the strong quantum spin regime at S =1 /2 to the S =1 case. Neutron scattering and magnetic susceptibility experiments can be used to test the destruction of the QSL phase when replacing S =1 /2 by S =1 localized moments in certain honeycomb compounds.
Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field
International Nuclear Information System (INIS)
Rezania, H.
2017-01-01
We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.
Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field
Energy Technology Data Exchange (ETDEWEB)
Rezania, H., E-mail: rezania.hamed@gmail.com
2017-02-01
We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.
Generation of an induced pluripotent stem cell line from an adult male with 45,X/46,XY mosaicism
Directory of Open Access Journals (Sweden)
Yumei Luo
2018-03-01
Full Text Available Turner syndrome (TS with 45,X/46,XY mosaic karyotype is a rare sex chromosome disorder with an occurrence of 0.15‰ at birth. We report the generation of an induced pluripotent stem cell (iPSC line from peripheral blood mononuclear cells of a Chinese adult male with 45,X/46,XY mosaicism. The iPSC line retains the original 45,X/46,XY mosaic karyotype, expresses pluripotency markers and undergoes trilineage differentiation. Therefore, it offers an unprecedented cellular model to investigate the profound symptoms like infertility of TS in the male, and serve as a useful tool to develop therapies for the disease.
Topics on frustrated spin systems and high-temperature superconductors
International Nuclear Information System (INIS)
Lu, Yong.
1990-01-01
The numerical study of frustrated spin systems using the Monte Carlo simulation method and the analytic study of fluctuation phenomenon of the thermoelectric power near the superconducting transition using Green's function techniques are presented. The first frustrated system considered was the B-site antiferromagnetic (AF) spinel. Based on an Ising model, various thermodynamic and magnetic properties for both the fully frustrated structure and partially frustrated cases of a small tetragonal distortion were studied. When fully frustrated, an interesting short range order and some unusual scaling behavior were obtained. In the two tetragonally distorted cases, contracting and expanding in the crystallographic c-direction, AF long range orders and some hysteresis behavior were found. A general phase diagram was constructed as a function of the degree of the distortion. The other frustrated spin system that was studied is the magnetic phase of YBa2Cu3O(6+x). A classical spin model, was constructed, and various properties in its Ising, Heisenberg, and x-y versions were studied. The susceptibility was calculated as a function of temperature for various values of x. In the study on the thermopower fluctuation, the thermopower was determined by the linear response of the electric and heat currents to an electric field, and the linear responses were in turn calculated from correlation functions of the current
Skew information in the XY model with staggered Dzyaloshinskii-Moriya interaction
Energy Technology Data Exchange (ETDEWEB)
Qiu, Liang, E-mail: lqiu@cumt.edu.cn [School of Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Quan, Dongxiao [State Key Laboratory of Integrated Services Networks, Xidian University, Xi' an, Shaanxi 710071 (China); Pan, Fei; Liu, Zhi [School of Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China)
2017-06-01
We study the performance of the lower bound of skew information in the vicinity of transition point for the anisotropic spin-1/2 XY chain with staggered Dzyaloshinskii-Moriya interaction by use of quantum renormalization-group method. For a fixed value of the Dzyaloshinskii-Moriya interaction, there are two saturated values for the lower bound of skew information corresponding to the spin-fluid and Néel phases, respectively. The scaling exponent of the lower bound of skew information closely relates to the correlation length of the model and the Dzyaloshinskii-Moriya interaction shifts the factorization point. Our results show that the lower bound of skew information can be a good candidate to detect the critical point of XY spin chain with staggered Dzyaloshinskii-Moriya interaction.
46,XY female sex reversal syndrome with bilateral gonadoblastoma and dysgerminoma.
DU, Xue; Zhang, Xuhong; Li, Yongmei; Han, Yukun
2014-10-01
Sex reversal syndrome is a rare congenital condition of complete or disordered gonadal development leading to discordance between the genetic, gonadal and phenotypic sexes, including 46,XX and 46,XY. The gonadoblastoma on the Y-chromosome (GBY) region is associated with an increased risk of developing type II germ cell tumors/cancer. The present study reports a unique case of a phenotypically normal female (age 17 years), presenting with primary amenorrhea and later diagnosed with 46,XY female sex reversal syndrome. Following bilateral gonadectomy, bilateral gonadoblastoma and dysgerminoma were diagnosed. Thus, estrogen replacement therapy was administered periodically to promote the development of secondary sexual characteristics and menstruation, and to prevent osteoporosis. A four year follow-up showed no tumor recurrence and a regular menstrual cycle in this patient.
Collective modes in quantum lattice or three-dimensional XY model, 2
International Nuclear Information System (INIS)
Aoki, Toshizumi; Homma, Shigeo; Nakano, Fuzio
1982-01-01
An external field is applied to the XY model which was studied in a previous paper. With the help of Mori's memory function formalism, two types of collective modes are obtained. One of those, which was previously pointed out to correspond to the first sound in superfluid helium, survives at the critical temperature T sub(c). The other is a new mode, which disappears as a result of symmetry restored above T sub(c). This mode comes about owing to the coupling between the Goldstone mode and the energy fluctuation due to an external field, and is regarded to correspond to the second sound in superfluid helium. The linearized two-fluid hydrodynamic equations for superfluid helium are obtained in the context of the XY model, in which the detailed correspondence to the superfluid helium is clarified. (author)
Mulheres XY e a Síndrome de Insensibilidade aos Andrógenos
Directory of Open Access Journals (Sweden)
João Edson Marques Bandeira
2015-06-01
Full Text Available Objective: The aims are to report a case of Androgen-Insensitivity Syndrome (AIS and discuss aspects of opportune diagnosis and treatment of AIS. Case Report: C.F.F., 35, sought medical assistance reporting overweight and hypertension. During the anamnesis did not present menarche; with normal breast development, but late, around 14 years. Physical examination shows normal female external genitalia, with scarce pubic hair (P2 and the absence of axillary hair; breasts with normal development (M5. Conclusions: The result of the G band karyotype was 46, XY for the sisters and the screening in relatives revealed prepubescent girl with XY karyotype. The risk of tumor development is difficult to be predicted recently markers were identified that may be useful in determining individual risk and suggest the time of gonadectomy. The current consensus on the approach related to intersex disorders recommends gonadectomy at diagnosis for patients with AIS, after puberty, due to the ease of hormone replacement.
Scaling of quantum Fisher information close to the quantum phase transition in the XY spin chain
Energy Technology Data Exchange (ETDEWEB)
Ye, En-Jia, E-mail: yeenjia@jiangnan.edu.cn [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Hu, Zheng-Da [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Wu, Wei [Zhejiang Institute of Modern Physics and Physics Department, Zhejiang University, Hangzhou 310027 (China)
2016-12-01
The quantum phase transition of an XY spin chain is investigated by employing the quantum Fisher information encoded in the ground state. It is shown that the quantum Fisher information is an effective tool for characterizing the quantum criticality. The quantum Fisher information, its first and second derivatives versus the transverse field display the phenomena of sudden transition, sudden jump and divergence, respectively. Besides, the analysis of finite size scaling for the second derivative of quantum Fisher information is performed.
Design of X-Y steering magnet for extraction beamline of K-500 superconducting cyclotron
International Nuclear Information System (INIS)
Naser, Md. Zamal A.; Paul, S.; Bhunia, U.; Pradhan, J.; Dey, M.K.; Nandi, C.; Mallik, C.; Bhandari, R.K.
2005-01-01
The K-500 Superconducting Cyclotron is in the advanced stage of commissioning at VEC Centre, Kolkata. This accelerator is designed to accelerate up to maximum 80 MeV/nucleon energy. A X-Y steering magnet is essential to guide this high energy beam into the external high energy beam line. This paper describes the designing and the other related necessary aspects of such a steering magnet. (author)
Tata Laksana Kasus Perempuan dengan Pure Gonadal Dysgenesis 46, XY (Sindrom Swyer)
Kanadi Sumapradja; Mila Maidarti; Achmad K. Harzif; Budi Wiweko; Gita Pratama; Muharam Natadisastra; Andon Hestiantoro
2016-01-01
Disorders of sex development (DSD) adalah kelainan medis yang dikaitkan dengan ketidakcocokan antara kromosom, gonad dan fenotip. Sindrom Swyer adalah kelainan berupa disgenesis gonad 46,XY dan diikuti dengan tidak terjadinya pelepasan anti-mullerian hormone (AMH) dari gonad yang mengalami disgenesis sehingga mengakibatkan berkembangnya duktus muller menjadi uterus. Keadaan tersebut mengakibatkan pasien mengeluh amenorea primer dan organ seks sekunder tidak berkembang. Orientasi gender umumn...
High-fidelity state transfer over an unmodulated linear XY spin chain
International Nuclear Information System (INIS)
Bishop, C. Allen; Ou Yongcheng; Byrd, Mark S.; Wang Zhaoming
2010-01-01
We provide a class of initial encodings that can be sent with a high fidelity over an unmodulated, linear, XY spin chain. As an example, an average fidelity of 96% can be obtained using an 11-spin encoding to transmit a state over a chain containing 10 000 spins. An analysis of the magnetic-field dependence is given, and conditions for field optimization are provided.
Critical properties of Sudden Quench Dynamics in the anisotropic XY Model
Guo, Hongli; Liu, Zhao; Fan, Heng; Chen, Shu
2010-01-01
We study the zero temperature quantum dynamical critical behavior of the anisotropic XY chain under a sudden quench in a transverse field. We demonstrate theoretically that both quench magnetic susceptibility and two-particle quench correlation can be used to describe the dynamical quantum phase transition (QPT) properties. Either the quench magnetic susceptibility or the derivative of correlation functions as a function of initial magnetic field $a$ exhibits a divergence at the critical poin...
The size effect of the quantum coherence in the transverse-field XY chain
Energy Technology Data Exchange (ETDEWEB)
Wang, Lu; Yang, Cui-hong; Wang, Jun-feng [Department of Physics, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Lei, Shu-guo, E-mail: sglei@njtech.edu.cn [College of Science, Nanjing Tech University, Nanjing, 211816 (China)
2016-12-15
Based on the Wigner–Yanase skew information, the size effect of the quantum coherence in the ground state of the finite transverse-field spin-1/2 XY chain is explored. It is found that the first-order derivatives of the single-spin coherence and the two-spin local coherence both have scaling behaviors in the vicinity of the critical point. A simplified version of coherence is also studied and the same characteristics with its counterpart are found.
Distribution of sex chromosomes (XY) in lymphocyte metaphase spreads of dairy bulls
Kotikalapudi Rosaiah; Patel Rajesh Kumar; Medidi Hemanth; Sugali Nagaraju Naik
2013-01-01
Position of autosome and sex chromosomes in metaphase spreads is grate concerned of Cytogeneticians worldwide to understand cell biology. A few isolated studies have been conducted for the distribution of chromosomes in metaphase spread. Our studies reveal that most sex chromosomes (XY) remain on periphery and semi-periphery, 84.16% for X and 86.97% for Y respectively, in round metaphase spreads. The application of sex chromosome position in metaphase sprea...
Thermodynamical properties of random spin-1/2 XY chain with Dzyaloshinskii-Moriya interaction
International Nuclear Information System (INIS)
Derzhko, O.; Krokhmalskii, T.; Verkholyak, T.
1995-07-01
For computation of the equilibrium statistical properties of finite spin-1/2 XY chains with Dzyaloshinskii-Moriya interaction the suggested earlier approach (JMMM 140-144 (1995) 1623) is generalized. It is applied for calculation of transverse dynamical susceptibility of spin-1/2 Ising chain in non-random and random Gaussian transverse field with Dzyaloshinskii-Moriya interaction. (author). 7 refs, 2 figs
Sasidhar, Manda V; Itoh, Noriko; Gold, Stefan M; Lawson, Gregory W; Voskuhl, Rhonda R
2012-08-01
Many autoimmune diseases are characterised by a female predominance. This may be caused by sex hormones, sex chromosomes or both. This report uses a transgenic mouse model to investigate how sex chromosome complement, not confounded by differences in gonadal type, might contribute to lupus pathogenesis. Transgenic NZM2328 mice were created by deletion of the Sry gene from the Y chromosome, thereby separating genetic from gonadal sex. Survival, renal histopathology and markers of immune activation were compared in mice carrying the XX versus the XY(-) sex chromosome complement, with each genotype being ovary bearing. Mice with XX sex chromosome complement compared with XY(-) exhibited poorer survival rates and increased kidney pathology. Splenic T lymphocytes from XX mice demonstrated upregulated X-linked CD40 ligand expression and higher levels of activation markers ex vivo. Increased MMP, TGF and IL-13 production was found, while IL-2 was lower in XX mice. An accumulation of splenic follicular B cells and peritoneal marginal zone B cells was observed, coupled with upregulated costimulatory marker expression on B cells in XX mice. These data show that the XX sex chromosome complement, compared with XY(-), is associated with accelerated spontaneous lupus.
Gender role behavior in children with XY karyotype and disorders of sex development.
Jürgensen, Martina; Hiort, Olaf; Holterhus, Paul-Martin; Thyen, Ute
2007-03-01
Children exhibit gender-typical preferences in play, toys, activities and interests, and playmates. Several studies suggest that high concentrations of pre- and postnatal androgens contribute to male-typical behavior development, whereas female-typical behavior develops in the absence of high androgens levels. This study aims to explore the consequences of hypoandrogenization on gender-typical behavior in children who have an XY karyotype and disorder of sex development (DSD). Participants included 33 children (ages 2-12 years) with an XY karyotype and DSD; 21 reared as girls and 12 reared as boys. Children's preferred activities and interests and playmate preferences were assessed with parent report questionnaires, a structured free-play task, and choice of a toy to keep as a gift. Participant's responses were compared to those of children recruited in a pre-school and elementary school survey (N=166). In this study, the degree of hypoandrogenization as indicated by genital stage and diagnosis showed a significant relationship to nearly all of the gender-related behaviors assessed, supporting the hypothesis that masculinization of gender role behavior is a function of prenatal androgen exposure. Despite the fact that children with partial androgen effects reared as girls showed increased "boyish" behaviors, they did not show increased signs of gender identity confusion or instability on a group level. We conclude that androgen exposure plays a decisive role in the development of gender-typical behavior in children with XY karyotype and DSD conditions.
Behavioural Problems in Children with 46XY Disorders of Sex Development
Directory of Open Access Journals (Sweden)
Nalini M. Selveindran
2017-01-01
Full Text Available The aim of this study is to determine the behavioural problems of children with 46XY disorders of sex development (DSD with genital ambiguity and to identify the risk factors that may influence behaviour. The 27 participants (aged 6–18 years consisted of 21 patients raised as boys and 6 patients raised as girls. Control data were obtained from a representative sibling of each patient who was matched for age and gender. The study tool used was the Child Behaviour Checklist (CBCL, which is a parent-administered questionnaire. The analysis of the behavioural scores revealed that the patient group had poorer scores in the total, externalizing, and internalizing realms. This group also had poorer scores in the anxious-depressed, social, and rule-breaking realms as compared to the control group. In addition, the XY-F group had higher scores (more pathological than the XY-M group, although the difference in the scores was not statistically significant. A comparison of the prevalence of patients with scores in the clinical range with that of the control group was not statistically significant. These findings support the current recommendations that psychological counselling should be an integral part of the professional support offered to patients with DSD.
seXY: a tool for sex inference from genotype arrays.
Qian, David C; Busam, Jonathan A; Xiao, Xiangjun; O'Mara, Tracy A; Eeles, Rosalind A; Schumacher, Frederick R; Phelan, Catherine M; Amos, Christopher I
2017-02-15
Checking concordance between reported sex and genotype-inferred sex is a crucial quality control measure in genome-wide association studies (GWAS). However, limited insights exist regarding the true accuracy of software that infer sex from genotype array data. We present seXY, a logistic regression model trained on both X chromosome heterozygosity and Y chromosome missingness, that consistently demonstrated >99.5% sex inference accuracy in cross-validation for 889 males and 5,361 females enrolled in prostate cancer and ovarian cancer GWAS. Compared to PLINK, one of the most popular tools for sex inference in GWAS that assesses only X chromosome heterozygosity, seXY achieved marginally better male classification and 3% more accurate female classification. https://github.com/Christopher-Amos-Lab/seXY. Christopher.I.Amos@dartmouth.edu. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com
Ben Hadj Hmida, Imen; Mougou-Zerelli, Soumaya; Hadded, Anis; Dimassi, Sarra; Kammoun, Molka; Bignon-Topalovic, Joelle; Bibi, Mohamed; Saad, Ali; Bashamboo, Anu; McElreavey, Ken
2016-07-01
To determine the genetic cause of 46,XY primary amenorrhea in three 46,XY girls. Whole exome sequencing. University cytogenetics center. Three patients with unexplained 46,XY primary amenorrhea were included in the study. Potentially pathogenic variants were confirmed by Sanger sequencing, and familial segregation was determined where parents' DNA was available. Exome sequencing was performed in the three patients, and the data were analyzed for potentially pathogenic mutations. The functional consequences of mutations were predicted. Three novel homozygous nonsense mutations in the luteinizing hormone receptor (LHCGR) gene were identified:c.1573 C→T, p.Gln525Ter, c.1435 C→T p.Arg479Ter, and c.508 C→T, p.Gln170Ter. Inactivating mutations of the LHCGR gene may be a more common cause of 46,XY primary amenorrhea than previously considered. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Schirach, Richard von
2014-07-01
Finally the German atomic physicists around Heisenberg, von Weizsaecker, and Hahn worked on their ''uranium machine'' in a Swabian beer-cellar - and took themselves for the world elite of nuclear research. In imprisonment they heared from the dropping of the Hiroshima bomb - a shock. Richard von Schirach shows the hindered ''fathers of the German atomic bomb'' in close-up, their eagerness, their hybris, their true importance, and their attempts to give after the war a new interpretation of their own role. A book, which raises in the sense of Duerrenmatt the question for the responsibility of science.
International Nuclear Information System (INIS)
Nagpal, A.K.
1978-01-01
Contrary to the prevalent belief, it is shown here that for the spin-3/2 Rarita-Schwinger field in the presence of a fully quantized interaction, the (anti) commutation relations are compatible with the Heisenberg equations of motion. The latter are indeed the same as the Lagrangian equations of motion. Further, it is shown that the validity of the Heisenberg equations of motion does not depend upon the choice of the canonical variables
Un'estrema solitudine la vita e l'opera di Werner Heisenberg
Cassidy, David C
1996-01-01
Il genio di Werner Heisenberg attraversa l'orizzonte della fisica del nostro secolo come una meteora. Testimoniano della fecondità e dell'originalità del suo pensiero non solo il Nobel che gli fu assegnato a soli 32 anni, ma soprattutto i decisivi impulsi da lui dati alla fisica quantistica, alla teoria delle particelle elementari, alla teoria del nucleo. Si deve a Heisenberg quel "principio di indeterminazione" che ha rivoluzionato non solo il corso della fisica ma il modo di concepire la posizione dell'uomo nell'universo. L'interesse del libro, però, vuole andare oltre la fisica, giacché il curriculum del "ragazzo di campagna dei biondi capelli" rispecchia in forma emblematica l'ambiguo rapporto della scienza col potere.
Heisenberg 1901-1976 : le témoignage de sa femme
Heisenberg, Elisabeth
1990-01-01
Une femme raconte la vie de son mari, Werner Heisenberg, Prix Nobel de Physique 1932. Après une enfance heureuse, ce brillant étudiant fut l'élève d'Albert Einstein, Niels Bohr, Arnold Sommerfeld. Mais à l'époque de la montée du nazisme, le grand physicien refusa de quitter son pays, cautionnant ainsi le régime d'Hitler et participant à "l'effort de guerre", c'est-à-dire à la course à la bombe. Le témoignage d'Elisabeth Heisenberg bien que naturellement subjectif, permet de saisir les ressorts psychologiques du comportement d'un savant face aux terrifiantes réalités de son époque.
Un-equivalency theorem between deformed and undeformed Heisenberg-Weyl's algebras
International Nuclear Information System (INIS)
Zhang Jianzu
2006-01-01
Two fundamental issues about the relation between the deformed Heisenberg-Weyl algebra in noncommutative space and the undeformed one in commutative space are elucidated. First the un-equivalency theorem between two algebras is proved: the deformed algebra related to the undeformed one by a non-orthogonal similarity transformation is explored; furthermore, non-existence of a unitary similarity transformation which transforms the deformed algebra to the undeformed one is demonstrated. Secondly the uniqueness of realizing the deformed phase space variables via the undeformed ones is elucidated: both the deformed Heisenberg-Weyl algebra and the deformed bosonic algebra should be maintained under a linear transformation between two sets of phase space variables which fixes that such a linear transformation is unique. Elucidation of this un-equivalency theorem has basic meaning both in theory and experiment
Excitation of bond-alternating spin-1/2 Heisenberg chains by tunnelling electrons
International Nuclear Information System (INIS)
Gauyacq, J-P; Lorente, N
2014-01-01
Inelastic electron tunneling spectra (IETS) are evaluated for spin-1/2 Heisenberg chains showing different phases of their spin ordering. The spin ordering is controlled by the value of the two different Heisenberg couplings on the two sides of each of the chain's atoms (bond-alternating chains). The perfect anti-ferromagnetic phase, i.e. a unique exchange coupling, marks a topological quantum phase transition (TQPT) of the bond-alternating chain. Our calculations show that the TQPT is recognizable in the excited states of the chain and hence that IETS is in principle capable of discriminating the phases. We show that perfectly symmetric chains, such as closed rings mimicking infinite chains, yield the same spectra on both sides of the TQPT and IETS cannot reveal the nature of the spin phase. However, for finite size open chains, both sides of the TQPT are associated with different IETS spectra, especially on the edge atoms, thus outlining the transition. (paper)
The spin-s quantum Heisenberg ferromagnetic models in the physical magnon theory
International Nuclear Information System (INIS)
Liu, B.-G.; Pu, F.-C.
2001-01-01
The spin-s quantum Heisenberg ferromagnetic model is investigated in the physical magnon theory. The effect of the extra unphysical magnon states on every site is completely removed in the magnon Hamiltonian and during approximation procedure so that the condition †n i a n i >=0(n≥2s+1) is rigorously satisfied. The physical multi-magnon occupancy †n i a n i >(1≤n≤2s) is proportional to T 3n/2 at low temperature and is equivalent to 1/(2s+1) at the Curie temperature. The magnetization not only unified but also well-behaved from zero temperature to Curie temperature is obtained in the framework of the magnon theory for the spin-s quantum Heisenberg ferromagnetic model. The ill-behaved magnetizations at high temperature in earlier magnon theories are completely corrected. The relation of magnon (spin wave) theory with spin-operator decoupling theory is clearly understood
An addendum to the Heisenberg-Euler effective action beyond one loop
Energy Technology Data Exchange (ETDEWEB)
Gies, Holger; Karbstein, Felix [Helmholtz-Institut Jena,Fröbelstieg 3, 07743 Jena (Germany); Theoretisch-Physikalisches Institut, Abbe Center of Photonics,Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)
2017-03-21
We study the effective interactions of external electromagnetic fields induced by fluctuations of virtual particles in the vacuum of quantum electrodynamics. Our main focus is on these interactions at two-loop order. We discuss in detail the emergence of the renowned Heisenberg-Euler effective action from the underlying microscopic theory of quantum electrodynamics, emphasizing its distinction from a standard one-particle irreducible effective action. In our explicit calculations we limit ourselves to constant and slowly varying external fields, allowing us to adopt a locally constant field approximation. One of our main findings is that at two-loop order there is a finite one-particle reducible contribution to the Heisenberg-Euler effective action in constant fields, which was previously assumed to vanish. In addition to their conceptual significance, our results are relevant for high-precision probes of quantum vacuum nonlinearity in strong electromagnetic fields.
Optical probe of Heisenberg-Kitaev magnetism in α -RuCl3
Sandilands, Luke J.; Sohn, C. H.; Park, H. J.; Kim, So Yeun; Kim, K. W.; Sears, Jennifer A.; Kim, Young-June; Noh, Tae Won
2016-11-01
We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet α -RuCl3 . Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.
Quantum metrology subject to spatially correlated Markovian noise: restoring the Heisenberg limit
International Nuclear Information System (INIS)
Jeske, Jan; Cole, Jared H; Huelga, Susana F
2014-01-01
Environmental noise can hinder the metrological capabilities of entangled states. While the use of entanglement allows for Heisenberg-limited resolution, the largest permitted by quantum mechanics, deviations from strictly unitary dynamics quickly restore the standard scaling dictated by the central limit theorem. Product and maximally entangled states become asymptotically equivalent when the noisy evolution is both local and strictly Markovian. However, temporal correlations in the noise have been shown to lift this equivalence while fully (spatially) correlated noise allows for the identification of decoherence-free subspaces. Here we analyze precision limits in the presence of noise with finite correlation length and show that there exist robust entangled state preparations which display persistent Heisenberg scaling despite the environmental decoherence, even for small correlation length. Our results emphasize the relevance of noise correlations in the study of quantum advantage and could be relevant beyond metrological applications. (paper)
Nuclear spin-magnon relaxation in two-dimensional Heisenberg antiferromagnets
International Nuclear Information System (INIS)
Wal, A.J. van der.
1979-01-01
Experiments are discussed of the dependence on temperature and magnetic field of the longitudinal relaxation time of single crystals of antiferromagnetically ordered insulators, i.e. in the temperature range below the Neel temperature and in fields up to the spin-flop transition. The experiments are done on 19 F nuclei in the Heisenberg antiferromagnets K 2 MnF 4 and K 2 NiF 4 , the magnetic structure of which is two-dimensional quadratic. (C.F.)
Chiral-glass transition and replica symmetry breaking of a three-dimensional Heisenberg spin glass
Hukushima, K.; Kawamura, H.
2000-01-01
Extensive equilibrium Monte Carlo simulations are performed for a three-dimensional Heisenberg spin glass with the nearest-neighbor Gaussian coupling to investigate its spin-glass and chiral-glass orderings. The occurrence of a finite-temperature chiral-glass transition without the conventional spin-glass order is established. Critical exponents characterizing the transition are different from those of the standard Ising spin glass. The calculated overlap distribution suggests the appearance ...
Renormalization group treatment for spin waves in the randomly disordered Heisenberg chain
International Nuclear Information System (INIS)
Chaves, C.M.; Koiller, B.
1983-03-01
Local densities of states in the randomly disordered binary quantum Heisenberg chain using a generalization of a recently developed approach based on renormalization group ideas are calculated. It envolves decimating alternate apins along the chain in such a way as to obtain recursion relations to describe the renormalized set of Green's function equations of motion. The densities of states are richly structured, indicating that the method takes into account compositional fluctuations of arbitrary range. (Author) [pt
Extended Weyl-Heisenberg algebra and Rubakov-Spiridonov superalgebra: Anyonic realizations
International Nuclear Information System (INIS)
Daoud, M.; Douari, J.
2001-09-01
We give the realizations of the extended Weyl-Heisenberg (WH) algebra and the Rubakov-Spiridonov (RS) superalgebra in terms of anyons, characterized by the statistical parameter ν is an element of [0,1], on two-dimensional lattice. The construction uses anyons defined from usual fermionic oscillators (Lerda-Sciuto construction). The anyonic realization of the superalgebra sl(1/1) is also presented. (author)
Susceptibility and specific heat of the Heisenberg antiferromagnet on the Kagome lattice
International Nuclear Information System (INIS)
Bernhard, B.H.; Canals, B.; Lacroix, C.
2001-01-01
The dynamic susceptibility of the S=((1)/(2)) Heisenberg antiferromagnet is calculated on the Kagome lattice by means of a Green's function decoupling scheme. The spin-spin correlation functions decrease exponentially with distance. The specific heat exhibits a single-peak structure with a T 2 dependence at low temperature and the correct high-temperature behaviour. The calculated total change in entropy indicates a ground-state entropy of 0.46 ln 2
Ignatenko, A. N.; Irkhin, V. Yu.
2016-01-01
We have studied the Heisenberg antiferromagnets characterized by the magnetic structures with the periods being two times larger than the lattice period. We have considered all the types of the Bravais lattices (simple cubic, bcc and fcc) and divided all these antiferromagnets into 7 classes i.e. 3 plus 4 classes denoted with symbols A and B correspondingly. The order parameter characterizing the degeneracies of the magnetic structures is an ordinary Neel vector for A classes and so-called 4-...
Ground state representation of the infinite one-dimensional Heisenberg ferromagnet. Pt. 2
International Nuclear Information System (INIS)
Babbitt, D.; Thomas, L.
1977-01-01
In its ground state representation, the infinite, spin 1/2 Heisenberg chain provides a model for spin wave scattering, which entails many features of the quantum mechanical N-body problem. Here, we give a complete eigenfunction expansion for the Hamiltonian of the chain in this representation, for all numbers of spin waves. Our results resolve the questions of completeness and orthogonality of the eigenfunctions given by Bethe for finite chains, in the infinite volume limit. (orig.) [de
Phase transition induced for external field in tree-dimensional isotropic Heisenberg antiferromagnet
Neto, Minos A.; Viana, J. Roberto; Salmon, Octavio D. R.; Filho, E. Bublitz; de Sousa, J. Ricardo
2017-01-01
In this paper, we report mean-field and effective-field renormalization group calculations on the isotropic Heisenberg antiferromagnetic model under a longitudinal magnetic field. As is already known, these methods, denoted by MFRG and EFRG, are based on the comparison of two clusters of different sizes, each of them trying to mimic certain Bravais lattice. Our attention has been on the obtantion of the critical frontier in the plane of temperature versus magnetic field, for the simple cubic ...
Zakeri, Khalil
2017-01-11
This Topical Review presents an overview of the recent experimental results on the quantitative determination of the magnetic exchange parameters in ultrathin magnetic films and multilayers grown on different substrates. The experimental approaches for probing both the symmetric Heisenberg and the antisymmetric Dzyaloshinskii-Moriya exchange interaction in ultrathin magnetic films and at interfaces are discussed in detail. It is explained how the experimental spectrum of magnetic excitations can be used to quantify the strength of these interactions.
The indeterminability of the world. Heisenberg and the struggle about the soul of the world
International Nuclear Information System (INIS)
Lindley, D.
2008-01-01
With his detection of the so-called uncertainty or undeterminacy relation the young physicist Werner Heisenberg upsetted 1972 over centuries valid physical certainties. The American physicist and journalist David Lindley depicts in his fascinating story the birth and development of one of the most important knowledges of history of sciences, which faned a vehement controversy under the greatests minds of his time and changed deeply our view of the world
Large-n limit of the Heisenberg model: The decorated lattice and the disordered chain
International Nuclear Information System (INIS)
Khoruzhenko, B.A.; Pastur, L.A.; Shcherbina, M.V.
1989-01-01
The critical temperature of the generalized spherical model (large-component limit of the classical Heisenberg model) on a cubic lattice, whose every bond is decorated by L spins, is found. When L → ∞, the asymptotics of the temperature is T c ∼ aL -1 . The reduction of the number of spherical constraints for the model is found to be fairly large. The free energy of the one-dimensional generalized spherical model with random nearest neighbor interaction is calculated
Analytical results for entanglement in the five-qubit anisotropic Heisenberg model
International Nuclear Information System (INIS)
Wang Xiaoguang
2004-01-01
We solve the eigenvalue problem of the five-qubit anisotropic Heisenberg model, without use of Bethe's ansatz, and give analytical results for entanglement and mixedness of two nearest-neighbor qubits. The entanglement takes its maximum at Δ=1 (Δ>1) for the case of zero (finite) temperature with Δ being the anisotropic parameter. In contrast, the mixedness takes its minimum at Δ=1 (Δ>1) for the case of zero (finite) temperature
Zad, Hamid Arian; Movahhedian, Hossein
2016-08-01
Heat capacity of a mixed-three-spin (1/2,1,1/2) antiferromagnetic XXX Heisenberg chain is precisely investigated by use of the partition function of the system for which, spins (1,1/2) have coupling constant J1 and spins (1/2,1/2) have coupling constant J2. We verify tripartite entanglement for the model by means of the convex roof extended negativity (CREN) and concurrence as functions of temperature T, homogeneous magnetic field B and the coupling constants J1 and J2. As shown in our previous work, [H. A. Zad, Chin. Phys. B 25 (2016) 030303.] the temperature, the magnetic field and the coupling constants dependences of the heat capacity for such spin system have different behaviors for the entangled and separable states, hence, we did some useful comparisons between this quantity and negativities of its organized bipartite (sub)systems at entangled and separable states. Here, we compare the heat capacity of the mixed-three-spin (1/2,1,1/2) system with the CREN and the tripartite concurrence (as measures of the tripartite entanglement) at low temperature. Ground state phase transitions, and also, transition from ground state to some excited states are explained in detail for this system at zero temperature. Finally, we investigate the heat capacity behavior around those critical points in which these quantum phase transitions occur.
International Nuclear Information System (INIS)
Gault, Kristen B.; Gammon, Paul; Fortin, Danielle
2015-01-01
Highlights: • Characterizes the waters and minerals of a natural acid rock drainage (ARD). • Demonstrates that cold climate ARD is mostly similar to temperate systems. • Cold-climate differences impact kinetic rates and hydrologic seasonality. • Demonstrates that thermodynamic equilibrium governs the ARD system. • Demonstrates that extraneous inputs can be detected in the system. - Abstract: Acid rock drainage (ARD) is considered to be temperature-limited due to the diminished activity of Fe(II)-oxidizing microbes at low temperatures. Nonetheless, ARD streams are present in cold climates. This study presents a geochemical characterization of a cold climate ARD creek at the Zn–Pb XY deposit in Yukon, Canada, which showed highly elevated concentrations of dissolved zinc (up to 475 mg/L). Acid rock drainage at the XY deposit is likely generated via subsurface abiotic and biotic oxidation of sulfide minerals, and then exits as seeps at the headwaters of the creek. The uppermost reaches of the creek have the lowest pH levels (pH 3.3) and highest metal concentrations, with prolific precipitation of iron-hydroxysulfate and -oxyhydroxide mineral precipitates (schwertmannite, jarosite, and goethite), present as terraced iron formations (TIFs) at one sampling location. The lower reaches of the creek show a progressive pH increase (up to pH level 4.9) which occurs due to Fe(III)- and Al-hydrolysis, the neutralizing influence of carbonate-rich strata and/or ground waters, and dilution by surface waters entering the creek. Progressive pH neutralization causes a change in precipitate mineralogy to X-ray amorphous Al-hydroxysulfates, with a composition similar to aluminite and hydrobasaluminite, and amorphous Al(OH)_3. Natural attenuation of Cd, Zn, and Pb occurred downstream from the headwater seeps, which was likely influenced by adsorption reactions involving both metal-sulfate anions and metal-sulfate ternary complexes. Generally, the concentrations of Cd, Zn, and
Prudnikov, V. V.; Prudnikov, P. V.; Popov, I. S.
2018-03-01
A Monte Carlo numerical simulation of the specific features of nonequilibrium critical behavior is carried out for the two-dimensional structurally disordered XY model during its evolution from a low-temperature initial state. On the basis of the analysis of the two-time dependence of autocorrelation functions and dynamic susceptibility for systems with spin concentrations of p = 1.0, 0.9, and 0.6, aging phenomena characterized by a slowing down of the relaxation system with increasing waiting time and the violation of the fluctuation-dissipation theorem (FDT) are revealed. The values of the universal limiting fluctuation-dissipation ratio (FDR) are obtained for the systems considered. As a result of the analysis of the two-time scaling dependence for spin-spin and connected spin autocorrelation functions, it is found that structural defects lead to subaging phenomena in the behavior of the spin-spin autocorrelation function and superaging phenomena in the behavior of the connected spin autocorrelation function.
Energy Technology Data Exchange (ETDEWEB)
Delfin L, A
1997-12-31
The purpose of this work is to solve the neutron transport equation in discrete-ordinates and X-Y geometry by developing and using the strong discontinuous and strong modified discontinuous nodal finite element schemes. The strong discontinuous and modified strong discontinuous nodal finite element schemes go from two to ten interpolation parameters per cell. They are describing giving a set D{sub c} and polynomial space S{sub c} corresponding for each scheme BDMO, RTO, BL, BDM1, HdV, BDFM1, RT1, BQ and BDM2. The solution is obtained solving the neutron transport equation moments for each nodal scheme by developing the basis functions defined by Pascal triangle and the Legendre moments giving in the polynomial space S{sub c} and, finally, looking for the non singularity of the resulting linear system. The linear system is numerically solved using a computer program for each scheme mentioned . It uses the LU method and forward and backward substitution and makes a partition of the domain in cells. The source terms and angular flux are calculated, using the directions and weights associated to the S{sub N} approximation and solving the angular flux moments to find the effective multiplication constant. The programs are written in Fortran language, using the dynamic allocation of memory to increase efficiently the available memory of the computing equipment. (Author).
Disentanglement of two qubits coupled to an XY spin chain: Role of quantum phase transition
International Nuclear Information System (INIS)
Yuan Zigang; Li Shushen; Zhang Ping
2007-01-01
We study the disentanglement evolution of two spin qubits which interact with a general XY spin-chain environment. The dynamical process of the disentanglement is numerically and analytically investigated in the vicinity of a quantum phase transition (QPT) of the spin chain in both weak and strong coupling cases. We find that the disentanglement of the two spin qubits may be greatly enhanced by the quantum critical behavior of the environmental spin chain. We give a detailed analysis to facilitate the understanding of the QPT-enhanced decaying behavior of the coherence factor. Furthermore, the scaling behavior in the disentanglement dynamics is also revealed and analyzed
Duality-mediated critical amplitude ratios for the (2 + 1)-dimensional S = 1XY model
Nishiyama, Yoshihiro
2017-09-01
The phase transition for the (2 + 1)-dimensional spin-S = 1XY model was investigated numerically. Because of the boson-vortex duality, the spin stiffness ρs in the ordered phase and the vortex-condensate stiffness ρv in the disordered phase should have a close relationship. We employed the exact diagonalization method, which yields the excitation gap directly. As a result, we estimate the amplitude ratios ρs,v/Δ (Δ: Mott insulator gap) by means of the scaling analyses for the finite-size cluster with N ≤ 22 spins. The ratio ρs/ρv admits a quantitative measure of deviation from selfduality.
Dynamical properties of the S =1/2 random Heisenberg chain
Shu, Yu-Rong; Dupont, Maxime; Yao, Dao-Xin; Capponi, Sylvain; Sandvik, Anders W.
2018-03-01
We study dynamical properties at finite temperature (T ) of Heisenberg spin chains with random antiferromagnetic exchange couplings, which realize the random singlet phase in the low-energy limit, using three complementary numerical methods: exact diagonalization, matrix-product-state algorithms, and stochastic analytic continuation of quantum Monte Carlo results in imaginary time. Specifically, we investigate the dynamic spin structure factor S (q ,ω ) and its ω →0 limit, which are closely related to inelastic neutron scattering and nuclear magnetic resonance (NMR) experiments (through the spin-lattice relaxation rate 1 /T1 ). Our study reveals a continuous narrow band of low-energy excitations in S (q ,ω ) , extending throughout the q space, instead of being restricted to q ≈0 and q ≈π as found in the uniform system. Close to q =π , the scaling properties of these excitations are well captured by the random-singlet theory, but disagreements also exist with some aspects of the predicted q dependence further away from q =π . Furthermore we also find spin diffusion effects close to q =0 that are not contained within the random-singlet theory but give non-negligible contributions to the mean 1 /T1 . To compare with NMR experiments, we consider the distribution of the local relaxation rates 1 /T1 . We show that the local 1 /T1 values are broadly distributed, approximately according to a stretched exponential. The mean 1 /T1 first decreases with T , but below a crossover temperature it starts to increase and likely diverges in the limit of a small nuclear resonance frequency ω0. Although a similar divergent behavior has been predicted and experimentally observed for the static uniform susceptibility, this divergent behavior of the mean 1 /T1 has never been experimentally observed. Indeed, we show that the divergence of the mean 1 /T1 is due to rare events in the disordered chains and is concealed in experiments, where the typical 1 /T1 value is accessed.
Makrythanasis, Periklis; Bernard, Pascal; Kurosaka, Hiroshi; Vannier, Anne; Thauvin-Robinet, Christel; Borel, Christelle; Mazaud-Guittot, Séverine; Rolland, Antoine; Desdoits-Lethimonier, Christèle; Guipponi, Michel; Zimmermann, Céline; Stévant, Isabelle; Kuhne, Françoise; Conne, Béatrice; Santoni, Federico; Lambert, Sandy; Huet, Frederic; Mugneret, Francine; Jaruzelska, Jadwiga; Faivre, Laurence; Wilhelm, Dagmar; Jégou, Bernard; Trainor, Paul A.; Resh, Marilyn D.; Antonarakis, Stylianos E.; Nef, Serge
2014-01-01
The Hedgehog (Hh) family of secreted proteins act as morphogens to control embryonic patterning and development in a variety of organ systems. Post-translational covalent attachment of cholesterol and palmitate to Hh proteins are critical for multimerization and long range signaling potency. However, the biological impact of lipid modifications on Hh ligand distribution and signal reception in humans remains unclear. In the present study, we report a unique case of autosomal recessive syndromic 46,XY Disorder of Sex Development (DSD) with testicular dysgenesis and chondrodysplasia resulting from a homozygous G287V missense mutation in the hedgehog acyl-transferase (HHAT) gene. This mutation occurred in the conserved membrane bound O-acyltransferase (MBOAT) domain and experimentally disrupted the ability of HHAT to palmitoylate Hh proteins such as DHH and SHH. Consistent with the patient phenotype, HHAT was found to be expressed in the somatic cells of both XX and XY gonads at the time of sex determination, and Hhat loss of function in mice recapitulates most of the testicular, skeletal, neuronal and growth defects observed in humans. In the developing testis, HHAT is not required for Sertoli cell commitment but plays a role in proper testis cord formation and the differentiation of fetal Leydig cells. Altogether, these results shed new light on the mechanisms of action of Hh proteins. Furthermore, they provide the first clinical evidence of the essential role played by lipid modification of Hh proteins in human testicular organogenesis and embryonic development. PMID:24784881
On the hydrogen atom via Wigner-Heisenberg algebra
International Nuclear Information System (INIS)
Rodrigues, R. de Lima . Unidade Academica de Educacao.
2008-01-01
We extend the usual Kustaanheimo-Stiefel 4D → 3D mapping to study and discuss a constrained super-Wigner oscillator in four dimensions. We show that the physical hydrogen atom is the system that emerges in the bosonic sector of the mapped super 3D system. (author)
International Nuclear Information System (INIS)
Maertens, H.D.
1982-01-01
The inhomogenious structure of modern heavy water reactor fuel elements result in a strong spacial dependence of the neutron flux. The flux distribution can be calculated in detail by numerical methods, which describe exactly the geometrical heterogeniety and take into account the neutron flux anisotropy by higher transport theoretical approximations. Starting from the discrete ordinate method an approximation of the neutron transport equation has been developed, allowing for a cylindrical representation of the fuel-elements in a rectangular array of rods. The discretisation of the space variables, is based on the finite-difference approximation, defining a rectangular lattice in a two-dimensional cartesian coordinate system, which can be cut and replaced by circular mesh elements of a partially one-dimensional cylindrical coordinate system at arbitrary space points. To couple the two spacial regions the outer circle line of a cylindrical geometry is approximated in the cartesian system by a polygon with n >= 8. A cylindrical geometry is approximated in the cartesian system by a polygon with n>=8. A cylindrical geometry is thus enclosed by a system of two-dimensional rectangular, triangular and trapezoid mesh elements. The directional distribution of the neutron flux is conserved when switching from the xy-system to the cylindrical coordinate system. The angle discretisation by balanced sets of squares (EQsub(n)) allows a simple definition of transfer-coefficients for the redistribution of the neutron flux due to coordinate transformations. The procedure is verified and tested by selected problems. Possible applications and limits are discussed. (orig.) [de
Angular quadrature sets for the streaming ray method in x-y geometry
International Nuclear Information System (INIS)
England, R.; Filippone, W.L.
1983-01-01
Steaming ray (SR) computations normally employ a set of specially selected ray directions. For x-y geometry, these directions are not uniformly spaced in the azimuthal angle, nor do they conform to any of the standard quadrature sets in current use. For simplicity in all previous SR computations, uniform angular weights were used. This note investigates two methods--a bisection scheme and a Fourier scheme--for selecting more appropriate azimuthal angular weights. In the bisection scheme, the azimuthal weight assigned to an SR direction is half the angular spread (in the x-y plane) between its two adjacent ray directions. In the Fourier method, the weights are chosen such that the number of terms in a Fourier series exactly integrable on the interval (0, 2π) is maximized. Several sample calculations have been performed. While both the Fourier and bisection weights showed significant advantage over the uniform weights used previously, the Fourier scheme appears to be the best method. Lists of bisection and Fourier weights are given for quadrature sets containing 4, 8, 12, ..., 60 azimuthal SR directions
One-norm geometric quantum discord and critical point estimation in the XY spin chain
Energy Technology Data Exchange (ETDEWEB)
Cheng, Chang-Cheng; Wang, Yao; Guo, Jin-Liang, E-mail: guojinliang80@163.com
2016-11-15
In contrast with entanglement and quantum discord (QD), we investigate the thermal quantum correlation in terms of Schatten one-norm geometric quantum discord (GQD) in the XY spin chain, and analyze their capabilities in detecting the critical point of quantum phase transition. We show that the one-norm GQD can reveal more properties about quantum correlation between two spins, especially for the long-range quantum correlation at finite temperature. Under the influences of site distance, anisotropy and temperature, one-norm GQD and its first derivative make it possible to detect the critical point efficiently for a general XY spin chain. - Highlights: • Comparing with entanglement and QD, one-norm GQD is more robust versus the temperature. • One-norm GQD is more efficient in characterization of long-range quantum correlation between two distant qubits. • One-norm GQD performs well in highlighting the critical point of QPT at zero or low finite temperature. • One-norm GQD has a number of advantages over QD in detecting the critical point of the spin chain.
Thermal quantum coherence and correlation in the extended XY spin chain
Sha, Ya-Ting; Wang, Yue; Sun, Zheng-Hang; Hou, Xi-Wen
2018-05-01
Quantum coherence and correlation of thermal states in the extended XY spin chain are studied in terms of the recently proposed l1 norm, skew information, and Bures distance of geometry discord (BGD), respectively. The entanglement measured via concurrence is calculated for reference. A two-dimensional susceptibility is introduced to explore their capability in highlighting the critical lines associated with quantum phase transitions in the model. It is shown that the susceptibility of the skew information and BGD is a genuine indicator of quantum phase transitions, and characterizes the factorization. However, the l1 norm is trivial for the factorization. An explicit scaling law of BGD is captured at low temperature in the XY model. In contrast to the entanglement, quantum coherence reveals a kind of long-range nonclassical correlation. Moreover, the obvious relation among model parameters is extracted for the factorized line in the extended model. Those are instructive for the understanding of quantum coherence and correlation in the theory of quantum information, and quantum phase transitions and factorization in condensed-matter physics.
Case of successful IVF treatment of an oligospermic male with 46,XX/46,XY chimerism.
Laursen, R J; Alsbjerg, B; Vogel, I; Gravholt, C H; Elbaek, H; Lildballe, D L; Humaidan, P; Vestergaard, E M
2018-04-30
We present a case of an infertile male with 46,XX/46,XYchimerism fathering a child after ICSI procedure. Conventional cytogenetic analysis on chromosomes, derived from lymphocytes, using standard Q-banding procedures with a 450-550-band resolution and short-tandem-repeat analysis of 14 loci. Analysis of 20 metaphases from lymphocytes indicated that the proband was a karyotypic mosaic with an almost equal distribution between male and female cell lines. In total, 12 of 20 (60%) metaphases exhibited a normal female karyotype 46,XX, while 8 of 20 (40%) metaphases demonstrated a normal male karyotype 46,XY. No structural chromosomal abnormalities were present. Out of 14 STR loci, two loci (D18S51 and D21S11) showed four different alleles in peripheral blood, buccal mucosal cells, conjunctival mucosal cells, and seminal fluid. In three loci (D2S1338, D7S820, and vWA), three alleles were detected with quantitative differences that indicated presence of four alleles. In DNA extracted from washed semen, four alleles were detected in one locus, and three alleles were detected in three loci. This pattern is consistent with tetragametic chimerism. There were no quantitative significant differences in peak heights between maternal and paternal alleles. STR-analysis on DNA from the son confirmed paternity. We report a unique case with 46,XX/46,XY chimerism confirmed to be tetragametic, demonstrated in several tissues, with male phenotype and no genital ambiguity with oligospermia fathering a healthy child after IVF with ICSI procedure.
Çatlı, Gönül; Alparslan, Caner; Can, P Şule; Akbay, Sinem; Kelekçi, Sefa; Atik, Tahir; Özyılmaz, Berk; Dündar, Bumin N
2015-06-01
46,XY pure gonadal dysgenesis (Swyer syndrome) is characterized by normal female genitalia at birth. It usually first becomes apparent in adolescence with delayed puberty and amenorrhea. Rarely, patients can present with spontaneous breast development and/or menstruation. A fifteen-year-old girl presented to our clinic with the complaint of primary amenorrhea. On physical examination, her external genitals were completely female. Breast development and pubic hair were compatible with Tanner stage V. Hormonal evaluation revealed a hypergonadotropic state despite a normal estrogen level. Chromosome analysis revealed a 46,XY karyotype. Pelvic ultrasonography showed small gonads and a normal sized uterus for age. SRY gene expression was confirmed by multiplex polymerase chain reaction. Direct sequencing on genomic DNA did not reveal a mutation in the SRY, SF1 and WT1 genes. After the diagnosis of Swyer syndrome was made, the patient started to have spontaneous menstrual cycles and therefore failed to attend her follow-up visits. After nine months, the patient underwent diagnostic laparoscopy. Frozen examination of multiple biopsies from gonad tissues revealed gonadoblastoma. With this report, we emphasize the importance of performing karyotype analysis, which is diagnostic for Swyer syndrome, in all cases with primary or secondary amenorrhea even in the presence of normal breast development. We also suggest that normal pubertal development in patients with Swyer syndrome may be associated with the presence of a hormonally active tumor.
Performance of Multiplexed XY Resistive Micromegas detectors in a high intensity beam
Banerjee, D.; Burtsev, V.; Chumakov, A.; Cooke, D.; Depero, E.; Dermenev, A. V.; Donskov, S. V.; Dubinin, F.; Dusaev, R. R.; Emmenegger, S.; Fabich, A.; Frolov, V. N.; Gardikiotis, A.; Gninenko, S. N.; Hösgen, M.; Karneyeu, A. E.; Ketzer, B.; Kirsanov, M. M.; Konorov, I. V.; Kramarenko, V. A.; Kuleshov, S. V.; Levchenko, E.; Lyubovitskij, V. E.; Lysan, V.; Mamon, S.; Matveev, V. A.; Mikhailov, Yu. V.; Myalkovskiy, V. V.; Peshekhonov, V. D.; Peshekhonov, D. V.; Polyakov, V. A.; Radics, B.; Rubbia, A.; Samoylenko, V. D.; Tikhomirov, V. O.; Tlisov, D. A.; Toropin, A. N.; Vasilishin, B.; Arenas, G. Vasquez; Ulloa, P.; Crivelli, P.
2018-02-01
We present the performance of multiplexed XY resistive Micromegas detectors tested in the CERN SPS 100 GeV/c electron beam at intensities up to 3 . 3 × 105e- /(s ṡcm2) . So far, all studies with multiplexed Micromegas have only been reported for tests with radioactive sources and cosmic rays. The use of multiplexed modules in high intensity environments was not explored due to the effect of ambiguities in the reconstruction of the hit point caused by the multiplexing feature. For the specific mapping and beam intensities analyzed in this work with a multiplexing factor of five, more than 50% level of ambiguity is introduced due to particle pile-up as well as fake clusters due to the mapping feature. Our results prove that by using the additional information of cluster size and integrated charge from the signal clusters induced on the XY strips, the ambiguities can be reduced to a level below 2%. The tested detectors are used in the CERN NA64 experiment for tracking the incoming particles bending in a magnetic field in order to reconstruct their momentum. The average hit detection efficiency of each module was found to be ∼96% at the highest beam intensities. By using four modules a tracking resolution of 1.1% was obtained with ∼85% combined tracking efficiency.
Dual mechanism of chromatin remodeling in the common shrew sex trivalent (XY 1Y 2
Directory of Open Access Journals (Sweden)
Sergey N. Matveevsky
2017-11-01
Full Text Available Here we focus on the XY1Y2 condition in male common shrew Sorex araneus Linnaeus, 1758, applying electron microscopy and immunocytochemistry for a comprehensive analysis of structure, synapsis and behaviour of the sex trivalent in pachytene spermatocytes. The pachytene sex trivalent consists of three distinct parts: short and long synaptic SC fragments (between the X and Y1 and between the X and Y2, respectively and a long asynaptic region of the X in-between. Chromatin inactivation was revealed in the XY1 synaptic region, the asynaptic region of the X and a very small asynaptic part of the Y2. This inactive part of the sex trivalent, that we named the ‘head’, forms a typical sex body and is located at the periphery of the meiotic nucleus at mid pachytene. The second part or ‘tail’, a long region of synapsis between the X and Y2 chromosomes, is directed from the periphery into the nucleus. Based on the distribution patterns of four proteins involved in chromatin inactivation, we propose a model of meiotic silencing in shrew sex chromosomes. Thus, we conclude that pachytene sex chromosomes are structurally and functionally two different chromatin domains with specific nuclear topology: the peripheral inactivated ‘true’ sex chromosome regions (part of the X and the Y1 and more centrally located transcriptionally active autosomal segments (part of the X and the Y2.
A novel hybrid actuation mechanism based XY nanopositioning stage with totally decoupled kinematics
Zhu, Wu-Le; Zhu, Zhiwei; Guo, Ping; Ju, Bing-Feng
2018-01-01
This paper reports the design, analysis and testing of a parallel two degree-of-freedom piezo-actuated compliant stage for XY nanopositioning by introducing an innovative hybrid actuation mechanism. It mainly features the combination of two Scott-Russell and a half-bridge mechanisms for double-stage displacement amplification as well as moving direction modulation. By adopting the leaf-type double parallelogram (LTDP) structures at both input and output ends of the hybrid mechanism, the lateral stiffness and dynamic characteristics are significantly improved while the parasitic motions are greatly eliminated. The XY nanopositioning stage is constructed with two orthogonally configured hybrid mechanisms along with the LTDP mechanisms for totally decoupled kinematics at both input and output ends. An analytical model was established to describe the complete elastic deformation behavior of the stage, with further verification through the finite element simulation. Finally, experiments were implemented to comprehensively evaluate both the static and dynamic performances of the proposed stage. Closed-loop control of the piezoelectric actuators (PEA) by integrating strain gauges was also conducted to effectively eliminate the nonlinear hysteresis of the stage.
Tata Laksana Kasus Perempuan dengan Pure Gonadal Dysgenesis 46, XY (Sindrom Swyer
Directory of Open Access Journals (Sweden)
Kanadi Sumapradja
2016-06-01
Full Text Available Disorders of sex development (DSD adalah kelainan medis yang dikaitkan dengan ketidakcocokan antara kromosom, gonad dan fenotip. Sindrom Swyer adalah kelainan berupa disgenesis gonad 46,XY dan diikuti dengan tidak terjadinya pelepasan anti-mullerian hormone (AMH dari gonad yang mengalami disgenesis sehingga mengakibatkan berkembangnya duktus muller menjadi uterus. Keadaan tersebut mengakibatkan pasien mengeluh amenorea primer dan organ seks sekunder tidak berkembang. Orientasi gender umumnya adalah sebagai perempuan, karena kurangnya paparan hormon androgen terhadap otak. Tatalaksana kasus Disorders of sex development (DSD sangat mementingkan pasien (patient-centered sehingga tatalaksana medikamentosa maupun pembedahan harus berdasarkan pemahaman pasien terhadap orientasi gendernya. Pada makalah ini dilaporkan kasus sindrom swyer pada seorang perempuan usia 29 tahun dengan keluhan amenorea primer. Hasil analisis kromosom 46,XY (20 metafase dengan hormon follicle stimulating hormone (FSH 31.5miu/ml, luteinizing hormone (LH 10.8miu/ml, estradiol (E2 <5pg/ml, testosteron total (T <0.0025ng/ml. Tatalaksana medikamentosa adalah memberikan terapi hormon estrogen untuk membantu proses feminisasi. Karena risiko tinggi terjadinya tumor pada kasus disgenesis gonad intra-abdomen dengan kromosom Y, maka direncanakan tindakan gonadektomi. Kata kunci: Tatalaksana, Sindrom Swyer, pure gonadal dysgenesis Case Management of Pure Gonadal Dysgenesis 46, XY (Sindrom Swyer Abstract Disorders of sex development (DSD are medical conditions in which the development of chromosomal, gonadal or anatomic sex varies from normal and may be incongruent with each other. Swyer syndrome is a condition caused by pure gonadal dysgenesis 46,XY, which followed by inadequate anti-mullerian (AMH production results in maintenance and further development of mullerian duct into uterus. Therefore, many patients who suffer from this condition initially come with chief complaint of primary
International Nuclear Information System (INIS)
Mudry, Christopher; Wen Xiaogang
1999-01-01
Effective theories for random critical points are usually non-unitary, and thus may contain relevant operators with negative scaling dimensions. To study the consequences of the existence of negative-dimensional operators, we consider the random-bond XY model. It has been argued that the XY model on a square lattice, when weakly perturbed by random phases, has a quasi-long-range ordered phase (the random spin wave phase) at sufficiently low temperatures. We show that infinitely many relevant perturbations to the proposed critical action for the random spin wave phase were omitted in all previous treatments. The physical origin of these perturbations is intimately related to the existence of broadly distributed correlation functions. We find that those relevant perturbations do enter the Renormalization Group equations, and affect critical behavior. This raises the possibility that the random XY model has no quasi-long-range ordered phase and no Kosterlitz-Thouless (KT) phase transition
Directory of Open Access Journals (Sweden)
Maricilda Palandi de Mello
2011-12-01
Full Text Available The steroid 5α-reductase type II enzyme catalyzes the conversion of testosterone (T to dihydrotestosterone (DHT, and its deficiency leads to undervirilization in 46,XY individuals, due to an impairment of this conversion in genital tissues. Molecular analysis in the steroid 5α-reductase type II gene (SRD5A2 was performed in two 46,XY female siblings. SRD5A2 gene sequencing revealed that the patients were homozygous for p.Gln126Arg missense mutation, which results from the CGA > CAA nucleotide substitution. The molecular result confirmed clinical diagnosis of 46,XY disorder of sex development (DSD for the older sister and directed the investigation to other family members. Studies on SRD5A2 protein structure showed severe changes at NADPH binding region indicating that structural modeling analysis can be useful to evaluate the deleterious role of a mutation as causing 5α-reductase type II enzyme deficiency.
DEFF Research Database (Denmark)
Müller, J; Torsson, A; Damkjaer Nielsen, M
1991-01-01
We have investigated gonadal development and growth in 4 individuals (3 with 46,XY and 1 with 46,XX karyotype) with P450scc deficiency. One patient died at 2 months of age from adrenal insufficiency, while the remaining 3 individuals were healthy and developed normally (age at follow-up: 18, 10...... and 8 years). In the surviving individuals, the diagnosis was established during the first 2-4 months of life by extensive endocrine studies of blood and urine. In the remaining patient, the diagnosis was made on the basis of karyotype (46,XY), anatomy of internal and external genitalia and adrenal...... pathology. Gonadectomy was performed in the 2 surviving 46,XY individuals at the age of 7 years, and histological examination showed normal testicular morphology but very few germ cells. Postmortem examination of the testes of the 2-month-old subject showed normal testicular histology, and quantitative...
International Nuclear Information System (INIS)
Tao, Ruibao.
1991-09-01
A method is developed to make a Bose transformation which is restricted in proper space. A self-consistent independent spin wave representation (SCISWR) is found for two dimensional isotropic antiferromagnet of Heisenberg square lattices. In the SCISWR, we have successfully done the renormalization from both the dynamic and kinematic interaction and calculated the corrections from the correlations of the nearest neighbour and next nearest neighbour sites. An anisotropic excitation energy of spin wave in improper space is found self-consistently and has a gap. The difficulty of divergence appearing from higher order perturbation terms in the conventional spin wave theory has been overcome and the convergence in our approach seems quite good. We find the energy of ground state E approx. -0.659 in low order approximation and the magnetization of sublattice M z = 0.430 x (N/2) for system with spin 1/2. It is also proved that a physical spin excitation restricted in proper space is still isotropic and has no gap. (author). 17 refs
Theory of the orthogonal dimer Heisenberg spin model for SrCu sub 2 (BO sub 3) sub 2
Miyahara, S
2003-01-01
The magnetic properties of SrCu sub 2 (BO sub 3) sub 2 are reviewed from a theoretical point of view. SrCu sub 2 (BO sub 3) sub 2 is a new two-dimensional spin gap system and its magnetic properties are well described by a spin-1/2 antiferromagnetic Heisenberg model of the orthogonal dimer lattice. The model has a dimer singlet ground state whose exactness was proven by Shastry and Sutherland for a topologically equivalent model more than 20 years ago. The exactness of the ground state is maintained even if interlayer couplings are introduced for SrCu sub 2 (BO sub 3) sub 2. In the two-dimensional model, quantum phase transitions take place between different ground states for which three phases are expected: a gapped dimer singlet state, a plaquette resonating valence bond state and a gapless magnetic ordered state. Analysis of the experimental data shows that the dimer singlet ground state is realized in SrCu sub 2 (BO sub 3) sub 2. The orthogonality of the dimer bonds, which is the underlying symmetry of th...
Energy Technology Data Exchange (ETDEWEB)
Belgiorno, Francesco [Politecnico di Milano, Dipartimento di Matematica, Milano (Italy); INdAM-GNFM, Milano (Italy); Cacciatori, Sergio L. [Universita dell' Insubria, Department of Science and High Technology, Como (Italy); INFN sezione di Milano, Milano (Italy); Dalla Piazza, Francesco [Universita ' ' La Sapienza' ' , Dipartimento di Matematica, Roma (Italy); Doronzo, Michele [Universita dell' Insubria, Department of Science and High Technology, Como (Italy)
2016-06-15
We investigate the quantisation in the Heisenberg representation of a model which represents a simplification of the Hopfield model for dielectric media, where the electromagnetic field is replaced by a scalar field φ and the role of the polarisation field is played by a further scalar field ψ. The model, which is quadratic in the fields, is still characterised by a non-trivial physical content, as the physical particles correspond to the polaritons of the standard Hopfield model of condensed matter physics. Causality is also taken into account and a discussion of the standard interaction representation is also considered. (orig.)
A TBA approach to thermal transport in the XXZ Heisenberg model
Zotos, X.
2017-10-01
We show that the thermal Drude weight and magnetothermal coefficient of the 1D easy-plane Heisenberg model can be evaluated by an extension of the Bethe ansatz thermodynamics formulation by Takahashi and Suzuki (1972 Prog. Theor. Phys. 48 2187). They have earlier been obtained by the quantum transfer matrix method (Klümper 1999 Z. Phys. B 91 507). Furthermore, this approach can be applied to the study of the far-out of equilibrium energy current generated at the interface between two semi-infinite chains held at different temperatures.
Heisenberg XXX Model with General Boundaries: Eigenvectors from Algebraic Bethe Ansatz
Directory of Open Access Journals (Sweden)
Samuel Belliard
2013-11-01
Full Text Available We propose a generalization of the algebraic Bethe ansatz to obtain the eigenvectors of the Heisenberg spin chain with general boundaries associated to the eigenvalues and the Bethe equations found recently by Cao et al. The ansatz takes the usual form of a product of operators acting on a particular vector except that the number of operators is equal to the length of the chain. We prove this result for the chains with small length. We obtain also an off-shell equation (i.e. satisfied without the Bethe equations formally similar to the ones obtained in the periodic case or with diagonal boundaries.
De La Rosa Gomez, Alejandro; MacKay, Niall; Regelskis, Vidas
2017-04-01
We present a general method of folding an integrable spin chain, defined on a line, to obtain an integrable open spin chain, defined on a half-line. We illustrate our method through two fundamental models with sl2 Lie algebra symmetry: the Heisenberg XXX and the Inozemtsev hyperbolic spin chains. We obtain new long-range boundary Hamiltonians and demonstrate that they exhibit Yangian symmetries, thus ensuring integrability of the models we obtain. The method presented provides a ;bottom-up; approach for constructing integrable boundaries and can be applied to any spin chain model.
Cálculo de la concurrencia para el modelo de Heisenberg
Castellanos,R; Franco,R; Silva-Valencia,J
2010-01-01
La concurrencia es una cantidad que nos permite medir el grado de entreveramiento que presenta un sistema cuántico y se puede calcular a partir de la matriz densidad reducida. En este artículo mostramos explicitamente como calcular la concurrencia para una cadena finita de espines s =1/2 descrita por el modelo de Heisenberg anistrópico. Nosotros mostramos que para cadenas finitas la concurrencia tiene un máximo en el punto crítico Δ = 1, la cual es una de las principales características ...
Monte Carlo study of four-spinon dynamic structure function in antiferromagnetic Heisenberg model
International Nuclear Information System (INIS)
Si-Lakhal, B.; Abada, A.
2003-11-01
Using Monte Carlo integration methods, we describe the behavior of the exact four-s pinon dynamic structure function S 4 in the antiferromagnetic spin 1/2 Heisenberg quantum spin chain as a function of the neutron energy ω and momentum transfer k. We also determine the fourspinon continuum, the extent of the region in the (k, ω) plane outside which S 4 is identically zero. In each case, the behavior of S 4 is shown to be consistent with the four-spinon continuum and compared to the one of the exact two-spinon dynamic structure function S 2 . Overall shape similarity is noted. (author)
The night of the physicists. Heisenberg, Hahn, Weizsaecker, and the German bomb
International Nuclear Information System (INIS)
Schirach, Richard von
2014-01-01
Finally the German atomic physicists around Heisenberg, von Weizsaecker, and Hahn worked on their ''uranium machine'' in a Swabian beer-cellar - and took themselves for the world elite of nuclear research. In imprisonment they heared from the dropping of the Hiroshima bomb - a shock. Richard von Schirach shows the hindered ''fathers of the German atomic bomb'' in close-up, their eagerness, their hybris, their true importance, and their attempts to give after the war a new interpretation of their own role. A book, which raises in the sense of Duerrenmatt the question for the responsibility of science.
Large field-induced gap of Kitaev-Heisenberg paramagnons in $\\alpha$-RuCl$_{3}$
Hentrich, Richard; Wolter, Anja U. B.; Zotos, Xenophon; Brenig, Wolfram; Nowak, Domenic; Isaeva, Anna; Doert, Thomas; Banerjee, Arnab; Lampen-Kelley, Paula; Mandrus, David G.; Nagler, Stephen E.; Sears, Jennifer; Kim, Young-June; Büchner, Bernd; Hess, Christian
2017-01-01
The honeycomb Kitaev-Heisenberg model is a source of a quantum spin liquid with Majorana fermions and gauge flux excitations as fractional quasiparticles. In the quest of finding a pertinent material, $\\alpha$-RuCl$_{3}$ recently emerged as a prime candidate. Here we unveil highly unusual low-temperature heat conductivity $\\kappa$ of $\\alpha$-RuCl$_{3}$: beyond a magnetic field of $B_c\\approx$ 7.5 T, $\\kappa$ increases by about one order of magnitude, resulting in a large magnetic field depen...
Event-chain algorithm for the Heisenberg model: Evidence for z≃1 dynamic scaling.
Nishikawa, Yoshihiko; Michel, Manon; Krauth, Werner; Hukushima, Koji
2015-12-01
We apply the event-chain Monte Carlo algorithm to the three-dimensional ferromagnetic Heisenberg model. The algorithm is rejection-free and also realizes an irreversible Markov chain that satisfies global balance. The autocorrelation functions of the magnetic susceptibility and the energy indicate a dynamical critical exponent z≈1 at the critical temperature, while that of the magnetization does not measure the performance of the algorithm. We show that the event-chain Monte Carlo algorithm substantially reduces the dynamical critical exponent from the conventional value of z≃2.
Quantum Heisenberg antiferromagnetic chains with exchange and single-ion anisotropies
International Nuclear Information System (INIS)
Peters, D; Selke, W; McCulloch, I P
2010-01-01
Using density matrix renormalization group calculations, ground state properties of the spin-1 Heisenberg chain with exchange and quadratic single-ion anisotropies in an external field are studied, for special choices of the two kinds of anisotropies. In particular, the phase diagram includes antiferromagnetic, spin-liquid (or spin-flop), IS2, and supersolid (or biconical) phases. Especially, new features of the spin-liquid and supersolid phases are discussed. Properties of the quantum chains are compared to those of corresponding classical spin chains.
The low-temperature phase of the Heisenberg antiferromagnet in a fermionic representation
International Nuclear Information System (INIS)
Azakov, S.; Dilaver, M.; Oztas, A.M.
1999-09-01
Thermal properties of the ordered phase of the spin 1/2 isotropic Heisenberg Antiferromagnet on a d-dimensional hypercubical lattice are studied within the fermionic representation when the constraint of a single occupancy condition is taken into account by the method suggested by Popov and Fedotov. Using a saddle point approximation in the path integral approach we discuss not only the leading order but also the fluctuations around the saddle point at one-loop level. The influence of taking into account the single occupancy condition is discussed at all steps. (author)
International Nuclear Information System (INIS)
Zhan-Hai, Dong
2009-01-01
In order to look for the 120° order phase of triangular lattice Heisenberg antiferromagnet with long range couplings, the Hamiltonian is diagonalized with the Bogoliubov transformation within linear spin-wave approximation. It is found that when the long range spin couplings are taken into account, the transformation is valid only for certain regions in the spin coupling parameter space. These regions just correspond to the 120° (or Néel) ordered phase, which is very different from square lattice in terms of shape, size and topological property
The relation between mass-gap amplitudes and critical exponents in the Heisenberg model
International Nuclear Information System (INIS)
Alcaraz, F.C.; Felicio, J.R.D. de
1985-01-01
A recent result concerning the universality of the ratio of mass-gap amplitudes using the well known 1-D Heisenberg model which is the quantum version of the two-dimensional eight-vertex model is discussed. The believed extended scaling relation (x sub(p) = x sub(is an element of)/4) relating the polarization and energy anomalous dimensions is confirmed. The exponent, α, ν, γ sub(m) and γ sub(p) is also obtained by usual phenomenological renormalization group methods. (Author) [pt
Critical behavior of the three-dimensional Heisenberg antiferromagnet RbMnF_{3}
DEFF Research Database (Denmark)
Coldea, R.; Cowley, R.A.; Perring, T.G.
1998-01-01
component evolves below T-N into the longitudinal susceptibility identified in an earlier polarized neutron experiment. The intensity and energy width of the longitudinal scattering decrease on cooling below T-N. Down to the lowest temperatures where the longitudinal susceptibility could be measured......The magnetic critical scattering of the near-ideal three-dimensional Heisenberg antiferromagnet (AF) RbMnF3 has been remeasured using neutron scattering. The critical dynamics has been studied in detail in the temperature range 0.77T(N)
International Nuclear Information System (INIS)
Murtazaev, A.K.; Ramazanov, M.K.; Badiev, M.K.
2009-01-01
The critical properties of the 3D frustrated antiferromagnetic Heisenberg model on a triangular lattice are investigated by the replica Monte Carlo method. The static magnetic and chiral critical exponents of heat capacity a = 0.05(2), magnetization Β 0.30(1), Β k = 0.52(2), susceptibility Γ = 1.36(2), Γ k = 0.93(3), and correlation radius Ν 0.64(1), Ν k = 0.64(2) are calculated by using the finitesize scaling theory. The critical Fisher exponents η = - 0.06(3), η k = 0.63(4) for this model are estimated for the first time. A new universality class of the critical behavior is shown to be formed by the 3D frustrated Heisenberg model on the triangular lattice. A type of the interlayer exchange interaction is found to influence the universality class of antiferromagnetic Heisenberg model on the a triangular lattice.
When Bertolt Brecht looked into Heisenberg´s microscope
CERN. Geneva; Peter, Andrej; Ernst, Karin; Arnold, Lukas
2013-01-01
The meeting will be hosted in Vidyo (http://information-technology.web.cern.ch/services/fe/vidyo) In order to connect from your PC firstcheck if your requirements are o.k. http://stage.xcarab.com/vidyo/syscheck/ . You need a microphone to be connected at least to hear the speaker. To connect If you want to connect to the system using your CERN account you should register to the Vidyo service (http://information-technology.web.cern.ch/services/fe/vidyo/howto/users-register-vidyo-service). Go to the Join Now! link below and click on it. You will be directed to the Vydio Portal. You can login as a "guest" or you can use your CERN account. If you login as a "guest" you will only need to enteer a random Guest Name and click on Join. If you want to login with your CERN user account, put in your regeistered account (username and password are the same of your standard CERN account) You will be proposed to to download and install the Vid...
Energy Technology Data Exchange (ETDEWEB)
Hui, Ning-Ju [Department of Applied Physics, Xi' an University of Technology, Xi' an 710054 (China); Xu, Yang-Yang; Wang, Jicheng; Zhang, Yixin [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Hu, Zheng-Da, E-mail: huyuanda1112@jiangnan.edu.cn [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China)
2017-04-01
We investigate the properties of geometric quantum coherence in the XY spin-1/2 chain with staggered Dzyaloshinsky-Moriya interaction via the quantum renormalization-group approach. It is shown that the geometric quantum coherence and its coherence susceptibility are effective to detect the quantum phase transition. In the thermodynamic limit, the geometric quantum coherence exhibits a sudden jump. The coherence susceptibilities versus the anisotropy parameter and the Dzyaloshinsky-Moriya interaction are infinite and vanishing, respectively, illustrating the distinct roles of the anisotropy parameter and the Dzyaloshinsky-Moriya interaction in quantum phase transition. Moreover, we also explore the finite-size scaling behaviors of the coherence susceptibilities. For a finite-size chain, the coherence susceptibility versus the phase-transition parameter is always maximal at the critical point, indicating the dramatic quantum fluctuation. Besides, we show that the correlation length can be revealed by the scaling exponent for the coherence susceptibility versus the Dzyaloshinsky-Moriya interaction.
Bioactive steroids and sorbicillinoids isolated from the endophytic fungus Trichoderma sp. Xy24.
Zhao, Jin-Lian; Zhang, Min; Liu, Ji-Mei; Tan, Zhen; Chen, Ri-Dao; Xie, Ke-Bo; Dai, Jun-Gui
2017-10-01
A new steroid glucoside (1), along with nine known steroids (2-10) and four known sorbicillinoids (11-14), were isolated from the endophytic fungus Trichoderma sp. Xy24. Their structures were elucidated on the basis of spectroscopic data analyses and by comparison with reported data. Compounds 3, 5-7, 9, 10, and 13 exhibited significant inhibitory effects on HIV-1 virus with IC 50 values ranging 1.9-9.3 μM; compounds 10, 13, and 14 showed potent inhibitory activity on LPS-induced NO production in BV2 microglia cells with inhibitory rates of 108.2, 100, and 75.1% at 10 μM, respectively. In addition, compound 10 displayed moderate cytotoxicity against BCG823 and HePG2 cell lines with IC 50 values of 11.1 and 17.7 μM, respectively.
Dynamics of dimer and z spin component fluctuations in spin-1/2 XY chain
Directory of Open Access Journals (Sweden)
P.Hlushak
2005-01-01
Full Text Available One-dimensional quantum spin-1/2 XY models admit the rigorous analysis not only of their static properties (i.e. the thermodynamic quantities and the equal-time spin correlation functions but also of their dynamic properties (i.e. the different-time spin correlation functions, the dynamic susceptibilities, the dynamic structure factors. This becomes possible after exploiting the Jordan-Wigner transformation which reduces the spin model to a model of spinless noninteracting fermions. A number of dynamic quantities (e.g. related to transverse spin operator or dimer operator fluctuations are entirely determined by two-fermion excitations and can be examined in much detail.
An XXX male resulting from paternal X-Y interchange and maternal X-X nondisjunction.
Annerén, G; Andersson, M; Page, D C; Brown, L G; Berg, M; Läckgren, G; Gustavson, K H; de la Chapelle, A
1987-01-01
A 2-year-old boy was found to have a 47,XXX karyotype. Restriction-fragment-length-polymorphism analysis showed that, of his three X chromosomes, one is of paternal and two are of maternal origin. The results of Y-DNA hybridization were reminiscent of those in XX males in two respects. First, hybridization to Southern transfers revealed the presence in this XXX male of sequences derived from the Y-chromosomal short arm. Second, in situ hybridization showed that this Y DNA was located on the tip of the X-chromosomal short arm. We conclude that this XXX male resulted from the coincidence of X-X nondisjunction during maternal meiosis and aberrant X-Y interchange either during or prior to paternal meiosis. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:2889356
Absence of vortex condensation in a two dimensional fermionic XY model
International Nuclear Information System (INIS)
Cecile, D. J.; Chandrasekharan, Shailesh
2008-01-01
Motivated by a puzzle in the study of two-dimensional lattice quantum electrodynamics with staggered fermions, we construct a two-dimensional fermionic model with a global U(1) symmetry. Our model can be mapped into a model of closed packed dimers and plaquettes. Although the model has the same symmetries as the XY model, we show numerically that the model lacks the well-known Kosterlitz-Thouless phase transition. The model is always in the gapless phase showing the absence of a phase with vortex condensation. In other words the low energy physics is described by a noncompact U(1) field theory. We show that by introducing an even number of layers one can introduce vortex condensation within the model and thus also induce a Kosterlitz-Thouless transition.
Relación entre quimerismo xx/xy y el fenotipo pseudohermafrodita masculino en porcinos.
Directory of Open Access Journals (Sweden)
Reinartz E. Mónica
2001-09-01
Full Text Available La causa genética del pseudohermafroditismo no está bien dilucidada, sin embargo se han reportado distintos casos de pseudohermafroditas masculinos los cuales en la mayoría de los casos se han tratado de explicar por efectos hormonales sobre las gónadas en formación durante el desarrollo embrionario. Además se ha explorado poco la relación de este fenotipo con la constitución genómica de los organismos que presentan la disfunción sexual. En el presente trabajo se encontró una fuerte relación entre el quimerismo cromosómico XX/XY y el fenotipo pseudohermafrodita masculino exhibido por dos ejemplares de porcinos Landrace X Largewhite similar a lo encontrado en freemartinismo de bovinos.
Neutron-scattering cross section of the S=1/2 Heisenberg triangular antiferromagnet
DEFF Research Database (Denmark)
Lefmann, K.; Hedegård, P.
1994-01-01
In this paper we use a Schwinger-boson mean-field approach to calculate the neutron-scattering cross section from the S = 1/2 antiferromagnet with nearest-neighbor isotropic Heisenberg interaction on a two-dimensional triangular lattice. We investigate two solutions for T = 0: (i) a state with lo...... no elastic, but a set of broader dispersive spin excitations around kappa almost-equal-to (1/2, 0) and around kappa almost-equal-to (1/3, 1/3) for omega/E(g) = 2.5-4. It should thus be possible to distinguish these two states in a neutron-scattering experiment.......In this paper we use a Schwinger-boson mean-field approach to calculate the neutron-scattering cross section from the S = 1/2 antiferromagnet with nearest-neighbor isotropic Heisenberg interaction on a two-dimensional triangular lattice. We investigate two solutions for T = 0: (i) a state with long......-range order resembling the Neel state and (ii) a resonating valence bond or ''spin liquid'' state with an energy gap, E(g) almost-equal-to 0.17J, for the elementary excitations (spinons). For solution (ii) the neutron cross section shows Bragg rods at kappa = K = (1/3, 1/3), whereas solution (ii) shows...
Stapp`s quantum dualism: The James/Heisenberg model of consciousness
Energy Technology Data Exchange (ETDEWEB)
Noyes, H.P.
1994-02-18
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 along 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.
Study of interacting fields in a canonical formalism in Heisenberg picture of quantum field theory
International Nuclear Information System (INIS)
RANAIVOSON, R.T.R.
2011-01-01
In this work, we have made a study on the canonical formalism of the quantum field theory. Our contribution has been the development of a study using the Heisenberg picture. We showed that this approach may be useful for the description of quantum dynamics of interacting fields in bounded states. Our approach is to start from the lagrangian density of a classical theory from which one deduce the classical evolution equations of the fields via Euler-Lagrange equation for fields and establish the expression of conserved quantities characterizing the dynamics using the Noether theorem. Passing to the canonical quantization, fields and quantities characterizing the dynamics become quantum operators and evolution equations become operatorial evolution equations in Heisenberg picture. Expressions of quantum observable are also deduced from the expressions of classical conserved quantities. After, we showed that using the properties of fields operators and quantum states vectors, one can deduce from the operatorial evolution equations, the evolution equations for the wave functions of fermions and the evolution equations of expectation values of boson fields. For the illustration, various studies were conducted: the case of electrodynamics, the case of a general gauge theory and the case of the Standard Model. [fr
Critical behavior of the anisotropic Heisenberg model by effective-field renormalization group
de Sousa, J. Ricardo; Fittipaldi, I. P.
1994-05-01
A real-space effective-field renormalization-group method (ERFG) recently derived for computing critical properties of Ising spins is extended to treat the quantum spin-1/2 anisotropic Heisenberg model. The formalism is based on a generalized but approximate Callen-Suzuki spin relation and utilizes a convenient differential operator expansion technique. The method is illustrated in several lattice structures by employing its simplest approximation version in which clusters with one (N'=1) and two (N=2) spins are used. The results are compared with those obtained from the standard mean-field (MFRG) and Migdal-Kadanoff (MKRG) renormalization-group treatments and it is shown that this technique leads to rather accurate results. It is shown that, in contrast with the MFRG and MKRG predictions, the EFRG, besides correctly distinguishing the geometries of different lattice structures, also provides a vanishing critical temperature for all two-dimensional lattices in the isotropic Heisenberg limit. For the simple cubic lattice, the dependence of the transition temperature Tc with the exchange anisotropy parameter Δ [i.e., Tc(Δ)], and the resulting value for the critical thermal crossover exponent φ [i.e., Tc≂Tc(0)+AΔ1/φ ] are in quite good agreement with results available in the literature in which more sophisticated treatments are used.
Fischer, Andreas
2016-11-01
Optical flow velocity measurements are important for understanding the complex behavior of flows. Although a huge variety of methods exist, they are either based on a Doppler or a time-of-flight measurement principle. Doppler velocimetry evaluates the velocity-dependent frequency shift of light scattered at a moving particle, whereas time-of-flight velocimetry evaluates the traveled distance of a scattering particle per time interval. Regarding the aim of achieving a minimal measurement uncertainty, it is unclear if one principle allows to achieve lower uncertainties or if both principles can achieve equal uncertainties. For this reason, the natural, fundamental uncertainty limit according to Heisenberg's uncertainty principle is derived for Doppler and time-of-flight measurement principles, respectively. The obtained limits of the velocity uncertainty are qualitatively identical showing, e.g., a direct proportionality for the absolute value of the velocity to the power of 32 and an indirect proportionality to the square root of the scattered light power. Hence, both measurement principles have identical potentials regarding the fundamental uncertainty limit due to the quantum mechanical behavior of photons. This fundamental limit can be attained (at least asymptotically) in reality either with Doppler or time-of-flight methods, because the respective Cramér-Rao bounds for dominating photon shot noise, which is modeled as white Poissonian noise, are identical with the conclusions from Heisenberg's uncertainty principle.
RVB signatures in the spin dynamics of the square-lattice Heisenberg antiferromagnet
Ghioldi, E. A.; Gonzalez, M. G.; Manuel, L. O.; Trumper, A. E.
2016-03-01
We investigate the spin dynamics of the square-lattice spin-\\frac{1}{2} Heisenberg antiferromagnet by means of an improved mean-field Schwinger boson calculation. By identifying both, the long-range Néel and the RVB-like components of the ground state, we propose an educated guess for the mean-field magnetic excitation consisting on a linear combination of local and bond spin flips to compute the dynamical structure factor. Our main result is that when this magnetic excitation is optimized in such a way that the corresponding sum rule is fulfilled, we recover the low- and high-energy spectral weight features of the experimental spectrum. In particular, the anomalous spectral weight depletion at (π,0) found in recent inelastic neutron scattering experiments can be attributed to the interference of the triplet bond excitations of the RVB component of the ground state. We conclude that the Schwinger boson theory seems to be a good candidate to adequately interpret the dynamic properties of the square-lattice Heisenberg antiferromagnet.
International Nuclear Information System (INIS)
Paulinelli, H G; De Souza, S M; Rojas, Onofre
2013-01-01
In this paper we explore the entanglement in an orthogonal dimer-plaquette Ising–Heisenberg chain, assembled between plaquette edges, also known as orthogonal dimer plaquettes. The quantum entanglement properties involving an infinite chain structure are quite important, not only because the mathematical calculation is cumbersome but also because real materials are well represented by infinite chains. Using the local gauge symmetry of this model, we are able to map onto a simple spin-1 like Ising and spin-1/2 Heisenberg dimer model with single effective ion anisotropy. Thereafter this model can be solved using the decoration transformation and transfer matrix approach. First, we discuss the phase diagram at zero temperature of this model, where we find five ground states, one ferromagnetic, one antiferromagnetic, one triplet–triplet disordered and one triplet–singlet disordered phase, beside a dimer ferromagnetic–antiferromagnetic phase. In addition, we discuss the thermodynamic properties such as entropy, where we display the residual entropy. Furthermore, using the nearest site correlation function it is possible also to analyze the pairwise thermal entanglement for both orthogonal dimers. Additionally, we discuss the threshold temperature of the entangled region as a function of Hamiltonian parameters. We find a quite interesting thin reentrance threshold temperature for one of the dimers, and we also discuss the differences and similarities for both dimers. (paper)
Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory
International Nuclear Information System (INIS)
Li Liangsheng; Li Li; Chen Xiaosong
2009-01-01
The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation (MF). The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density ρ* = ρσ 3 = 0.224 and the reduced temperature T* = kT/ element of = 1.87 (σ is the diameter of Heisenberg hard sphere and element of is the coupling constant).
Sperm quality analysis in XX, XY and YY males of the Nile tilapia (Oreochromis niloticus).
Gennotte, V; François, E; Rougeot, C; Ponthier, J; Deleuze, S; Mélard, C
2012-07-01
In Nile tilapia (Oreochromis niloticus), individuals with atypical sexual genotype are commonly used in farming (use of YY males to produce all-male offspring), but they also constitute major tools to study sex determinism mechanisms. In other species, sexual genotype and sex reversal procedures affect different aspects of biology, such as growth, behavior and reproductive success. The aim of this study was to assess the influence of sexual genotype on sperm quality in Nile tilapia. Milt characteristics were compared in XX (sex-reversed), XY and YY males in terms of gonadosomatic index, sperm count, sperm motility and duration of sperm motility. Sperm motility was measured by computer-assisted sperm analysis (CASA) quantifying several parameters: total motility, progressive motility, curvilinear velocity, straight line velocity, average path velocity and linearity. None of the sperm traits measured significantly differed between the three genotypes. Mean values of gonadosomatic index, sperm concentration and sperm motility duration of XX, XY and YY males, respectively ranged from 0.92 to 1.33%, from 1.69 to 2.22 ×10(9) cells mL(-1) and from 18'04″ to 27'32″. Mean values of total motility and curvilinear velocity 1 min after sperm activation, respectively ranged from 53 to 58% and from 71 to 76 μm s(-1) for the three genotypes. After 3 min of activity, all the sperm motility and velocity parameters dropped by half and continued to slowly decrease thereafter. Seven min after activation, only 9 to 13% of spermatozoa were still progressive. Our results prove that neither sexual genotype nor hormonal sex reversal treatments affect sperm quality in male Nile tilapias with atypical sexual genotype. Copyright © 2012 Elsevier Inc. All rights reserved.
Aetiological bases of 46,XY disorders of sex development in the Hong Kong Chinese population.
Chan, Angel O K; But, W M; Lee, C Y; Lam, Y Y; Ng, K L; Loung, P Y; Lam, Aimen; Cheng, C W; Shek, C C; Wong, W S; Wong, K F; Wong, M Y; Tse, W Y
2015-12-01
Disorders of sex development are due to congenital defects in chromosomal, gonadal, or anatomical sex development. The objective of this study was to determine the aetiology of this group of disorders in the Hong Kong Chinese population. Five public hospitals in Hong Kong. Patients with 46,XY disorders of sex development under the care of paediatric endocrinologists between July 2009 and June 2011. Measurement of serum gonadotropins, adrenal and testicular hormones, and urinary steroid profiling. Mutational analysis of genes involved in sexual differentiation by direct DNA sequencing and multiplex ligation-dependent probe amplification. Overall, 64 patients were recruited for the study. Their age at presentation ranged from birth to 17 years. The majority presented with ambiguous external genitalia including micropenis and severe hypospadias. A few presented with delayed puberty and primary amenorrhea. Baseline and post-human chorionic gonadotropin-stimulated testosterone and dihydrotestosterone levels were not discriminatory in patients with or without AR gene mutations. Of the patients, 22 had a confirmed genetic disease, with 11 having 5α-reductase 2 deficiency, seven with androgen insensitivity syndrome, one each with cholesterol side-chain cleavage enzyme deficiency, Frasier syndrome, NR5A1-related sex reversal, and persistent Müllerian duct syndrome. Our findings suggest that 5α-reductase 2 deficiency and androgen insensitivity syndrome are possibly the two most common causes of 46,XY disorders of sex development in the Hong Kong Chinese population. Since hormonal findings can be unreliable, mutational analysis of the SRD5A2 and AR genes should be considered the first-line tests for these patients.
Directory of Open Access Journals (Sweden)
Marco Barchi
2008-05-01
Full Text Available During meiosis in most sexually reproducing organisms, recombination forms crossovers between homologous maternal and paternal chromosomes and thereby promotes proper chromosome segregation at the first meiotic division. The number and distribution of crossovers are tightly controlled, but the factors that contribute to this control are poorly understood in most organisms, including mammals. Here we provide evidence that the ATM kinase or protein is essential for proper crossover formation in mouse spermatocytes. ATM deficiency causes multiple phenotypes in humans and mice, including gonadal atrophy. Mouse Atm-/- spermatocytes undergo apoptosis at mid-prophase of meiosis I, but Atm(-/- meiotic phenotypes are partially rescued by Spo11 heterozygosity, such that ATM-deficient spermatocytes progress to meiotic metaphase I. Strikingly, Spo11+/-Atm-/- spermatocytes are defective in forming the obligate crossover on the sex chromosomes, even though the XY pair is usually incorporated in a sex body and is transcriptionally inactivated as in normal spermatocytes. The XY crossover defect correlates with the appearance of lagging chromosomes at metaphase I, which may trigger the extensive metaphase apoptosis that is observed in these cells. In addition, control of the number and distribution of crossovers on autosomes appears to be defective in the absence of ATM because there is an increase in the total number of MLH1 foci, which mark the sites of eventual crossover formation, and because interference between MLH1 foci is perturbed. The axes of autosomes exhibit structural defects that correlate with the positions of ongoing recombination. Together, these findings indicate that ATM plays a role in both crossover control and chromosome axis integrity and further suggests that ATM is important for coordinating these features of meiotic chromosome dynamics.
Familial X/Y Translocation Encompassing ARSE in Two Moroccan Siblings with Sensorineural Deafness.
Amasdl, Saadia; Smaili, Wiam; Natiq, Abdelhafid; Hassani, Amale; Sbiti, Aziza; Agadr, Aomar; Sanlaville, Damien; Sefiani, Abdelaziz
2017-01-01
Unbalanced translocations involving X and Y chromosomes are rare and associated with a contiguous gene syndrome. The clinical phenotype is heterogeneous including mainly short stature, chondrodysplasia punctata, ichthyosis, hypogonadism, and intellectual disability. Here, we report 2 brothers with peculiar gestalt, short stature, and hearing loss, who harbor an X/Y translocation. Physical examination, brainstem acoustic potential evaluation, bone age, hormonal assessment, and X-ray investigations were performed. Because of their dysmorphic features, karyotyping, FISH, and aCGH were carried out. The probands had short stature, hypertelorism, midface hypoplasia, sensorineural hearing loss, normal intelligence as well as slight radial and ulnar bowing with brachytelephalangy. R-banding identified a derivative X chromosome with an abnormally expanded short arm. The mother was detected as a carrier of the same aberrant X chromosome. aCGH disclosed a 3.1-Mb distal deletion of chromosome region Xp22.33pter. This interval encompasses several genes, especially the short stature homeobox (SHOX) and arylsulfatase (ARSE) genes. The final karyotype of the probands was: 46,Y,der(X),t(X;Y)(p22;q12).ish der(X)(DXYS129-,DXYS153-)mat.arr[hg19] Xp22.33(61091_2689408)×1mat,Xp22.33(2701273_3258404)×0mat,Yq11.222q12 (21412851_59310245)×2. Herein, we describe a Moroccan family with a maternally inherited X/Y translocation and discuss the genotype-phenotype correlations according to the deleted genes. © 2017 S. Karger AG, Basel.
A thermal-driven silicon micro xy-stage integrated with piezoresistive sensors for nano-positioning
International Nuclear Information System (INIS)
Choi, Young-Soo; Zhang, Yan; Lee, Dong-Weon
2012-01-01
This paper describes a novel micro xy-stage, driven by double-hot arm horizontal thermal micro-actuators integrated with a piezoresistive sensor (PS) for low-voltage operation and precise control. This micro xy-stage structure is linked with chevron beams and optimized to amplify the displacement generated by the micro-actuators that provide a pull force to the movable platform. The PS employed for in situ displacement detection and feedback control is fabricated at the base of a cold arm, which minimizes the influence of temperature change induced by electro-thermal heating. The micro xy-stage structure is defined through the use of a simple micromachining process, released by backside wet etching with a special tool. For an input power of approximately 44 mW, each chevron actuator provides about 16 µm and the total displacement of the platform is close to 32 µm. The sensitivity of the PS is better than 1 mV µm −1 , obtained from the amplified voltage output of the Wheatstone bridge circuit. The potential applications of the proposed micro xy-stage lie in micro- or nano-manipulation, as well as the positioning of ultra-small objects in nanotechnology. (paper)
A NEW HYPOTHESIS ON THE EVOLUTION OF SEX DETERMINATION IN VERTEBRATES - BIG FEMALES ZW, BIG MALES XY
KRAAK, SBM; DELOOZE, EMA
1993-01-01
Why are there two chromosomal sex-determining mechanisms in vertebrates; ZW/ZZ, meaning female heterogamety, and XX/XY, meaning male heterogamety? We propose an evolutionary explanation. Transition from environmental sex determination to genetic sex determination can result when an allele that
van Heerden C; Tiktak A
1994-01-01
This report gives a description of the graphical tool XY. This program is developed to be coupled with simulation models and database programs. The program contains options for creating line-graphs, scatter-graphs, area-graphs, ordination-graphs, countour-graphs, maps and vector diagrams. The
1971-01-01
Remote from the noise and bustle of Europe's capital cities, in the charming German lake-side town of Lindau, close to the borders of Austria and Switzerland, Nobel Prize Winners in physics gathered together from June 28-July 2 to talk of their science and its interaction with society.
DEFF Research Database (Denmark)
Albrechtslund, Anne-Mette Bech; Albrechtslund, Anders
of the series’ appeal is due to its epic chronicling of the flow of transgressing and intersecting knowledge environments in the story of Walter White’s gradual transformation from disheartened teacher to methamphetamine producing criminal mastermind. Walter uses his scientific training and knowledge...
Magnetic ordering of quasi-1 D S=1/2 Heisenberg antiferromagnet Cu benzoate at sub-mK temperatures
International Nuclear Information System (INIS)
Karaki, Y.; Masutomi, R.; Kubota, M.; Ishimoto, H.; Asano, T.; Ajiro, Y.
2003-01-01
We have measured the AC susceptibility of quasi-1D S=1/2 Heisenberg antiferromagnet Cu benzoate at temperatures down to 0.2 mK. A sharp susceptibility peak is observed at 0.8 mK under an earth field. This fact indicates a 3D ordering of linear chains coupled by a weak magnetic interaction between chains
Exactly solved mixed spin-(1,1/2) Ising–Heisenberg diamond chain with a single-ion anisotropy
International Nuclear Information System (INIS)
Lisnyi, Bohdan; Strečka, Jozef
2015-01-01
The mixed spin-(1,1/2) Ising–Heisenberg diamond chain with a single-ion anisotropy is exactly solved through the generalized decoration–iteration transformation and the transfer-matrix method. The decoration–iteration transformation is first used for establishing a rigorous mapping equivalence with the corresponding spin-1 Blume–Emery–Griffiths chain, which is subsequently exactly treated within the transfer-matrix technique. Apart from three classical ground states the model exhibits three striking quantum ground states in which a singlet-dimer state of the interstitial Heisenberg spins is accompanied either with a frustrated state or a polarized state or a non-magnetic state of the nodal Ising spins. It is evidenced that two magnetization plateaus at zero and/or one-half of the saturation magnetization may appear in low-temperature magnetization curves. The specific heat may display remarkable temperature dependences with up to three and four distinct round maxima in a zero and non-zero magnetic field, respectively. - Highlights: • Mixed spin-(1,1/2) Ising–Heisenberg diamond chain is exactly solved. • Quantum ground states with a singlet-dimer state of the Heisenberg spins are found. • Magnetization curve displays intermediate plateaus at zero and half of full magnetization. • Thermal dependences of specific heat may display up to four distinct peaks
Palacios-Gimenez, Octavio M; Milani, Diogo; Lemos, Bernardo; Castillo, Elio R; Martí, Dardo A; Ramos, Erica; Martins, Cesar; Cabral-de-Mello, Diogo C
2018-01-08
Neo-sex chromosome systems arose independently multiple times in evolution, presenting the remarkable characteristic of repetitive DNAs accumulation. Among grasshoppers, occurrence of neo-XY was repeatedly noticed in Melanoplinae. Here we analyzed the most abundant tandem repeats of R. bergii (2n = 22, neo-XY♂) using deep Illumina sequencing and graph-based clustering in order to address the neo-sex chromosomes evolution. The analyses revealed ten families of satDNAs comprising about ~1% of the male genome, which occupied mainly C-positive regions of autosomes. Regarding the sex chromosomes, satDNAs were recorded within centromeric or interstitial regions of the neo-X chromosome and four satDNAs occurred in the neo-Y, two of them being exclusive (Rber248 and Rber299). Using a combination of probes we uncovered five well-defined cytological variants for neo-Y, originated by multiple paracentric inversions and satDNA amplification, besides fragmented neo-Y. These neo-Y variants were distinct in frequency between embryos and adult males. The genomic data together with cytogenetic mapping enabled us to better understand the neo-sex chromosome dynamics in grasshoppers, reinforcing differentiation of neo-X and neo-Y and revealing the occurrence of multiple additional rearrangements involved in the neo-Y evolution of R. bergii. We discussed the possible causes that led to differences in frequency for the neo-Y variants between embryos and adults. Finally we hypothesize about the role of DNA satellites in R. bergii as well as putative historical events involved in the evolution of the R. bergii neo-XY.
Baldinotti, Fulvia; Cavallaro, Tiziana; Dati, Eleonora; Baroncelli, Giampiero I; Bertini, Veronica; Valetto, Angelo; Massart, Francesco; Fabrizi, Gian Maria; Zanette, Giampietro; Peroni, Diego; Bertelloni, Silvano
2018-01-01
In humans, Desert Hedgehog (DHH) gene mutations are a very rare cause of 46,XY gonadal dysgenesis (GD), eventually associated with peripheral neuropathy. Clinical records of 12 patients with 46,XY GD and unknown genetic background were reviewed and a 46,XY woman with peripheral neuropathy was individuated. Her 46,XX sister affected by similar neuropathy was also investigated. Genomic DNA was extracted and DHH exons sequenced and analyzed. A comparative genomic hybridization array was also performed. In both the 46,XY and 46,XX sisters, a homozygous c.554C>A mutation in exon 2 of the DHH gene was found, determining a premature termination codon (p.Ser 185*). Heterozygous consanguineous carrier parents showed neither reproductive problems nor peripheral neuropathy. In the proband and her sister, a 499-kb duplication in 9p22.1 was also found. A 46,XY European woman with 46,XY GD and a novel homozygous DHH pathogenic variant is reported, confirming that this gene plays a key role in male gonadal development. Her 46,XX sister, harboring the same mutation, showed normal internal and external female phenotype. Thus, DHH seems not to be involved in the ovarian development pathway or its postpubertal function. Homozygous DHH mutations cause a specific peripheral neuropathy in humans with both 46,XY and 46,XX karyotypes. © 2018 S. Karger AG, Basel.
Scalar potential for the gauged Heisenberg algebra and a non-polynomial antisymmetric tensor theory
International Nuclear Information System (INIS)
D'Auria, R.; Ferrara, S.; Trigiante, M.; Vaula, S.
2005-01-01
We study some issues related to the effective theory of Calabi-Yau compactifications with fluxes in type II theories. At first the scalar potential for a generic electric Abelian gauging of the Heisenberg algebra, underlying all possible gaugings of R-R isometries, is presented and shown to exhibit, in some circumstances, a 'dual' no-scale structure under the interchange of hypermultiplets and vector multiplets. Subsequently a new setting of such theories, when all R-R scalars are dualized into antisymmetric tensors, is discussed. This formulation falls in the class of non-polynomial tensor theories considered long ago by Freedman and Townsend and it may be relevant for the introduction of both electric and magnetic charges
Classical ground states of Heisenberg and X Y antiferromagnets on the windmill lattice
Jeevanesan, Bhilahari; Orth, Peter P.
2014-10-01
We investigate the classical Heisenberg and planar (X Y ) spin models on the windmill lattice. The windmill lattice is formed out of two widely occurring lattice geometries: a triangular lattice is coupled to its dual honeycomb lattice. Using a combination of iterative minimization, heat-bath Monte Carlo simulations, and analytical calculations, we determine the complete ground-state phase diagram of both models and find the exact energies of the phases. The phase diagram shows a rich phenomenology due to competing interactions and hosts, in addition to collinear and various coplanar phases, also intricate noncoplanar phases. We briefly outline different paths to an experimental realization of these spin models. Our extensive study provides a starting point for the investigation of quantum and thermal fluctuation effects.
Directory of Open Access Journals (Sweden)
Mihai V. Putz
2010-10-01
Full Text Available Within the path integral Feynman formulation of quantum mechanics, the fundamental Heisenberg Uncertainty Relationship (HUR is analyzed in terms of the quantum fluctuation influence on coordinate and momentum estimations. While introducing specific particle and wave representations, as well as their ratio, in quantifying the wave-to-particle quantum information, the basic HUR is recovered in a close analytical manner for a large range of observable particle-wave Copenhagen duality, although with the dominant wave manifestation, while registering its progressive modification with the factor √1-n2, in terms of magnitude n ε [0,1] of the quantum fluctuation, for the free quantum evolution around the exact wave-particle equivalence. The practical implications of the present particle-to-wave ratio as well as of the free-evolution quantum picture are discussed for experimental implementation, broken symmetry and the electronic localization function.
Magnetic Properties of the S=2 Heisenberg Antiferromagnetic Chain Compound MnCl3(bpy)
International Nuclear Information System (INIS)
Hagiwara, M; Idutsu, Y; Honda, Z; Yamamoto, S
2012-01-01
We report the results of magnetic susceptibilities at temperatures between 2 and 300 K, and magnetization in magnetic fields of up to 52 T on polycrystalline samples of MnCl 3 (bpy) (bpy=2, 2'-bipyridine) and the comparison with numerical calculations. This compound is one of the rare examples of the spin 2 quasi-one-dimensional Heisenberg antiferromagnet, and the magnetic properties of tiny single crystal samples were reported previously. The temperature dependence of magnetic susceptibility and the magnetization curve after subtracting the contribution of magnetic impurity are well fitted to those calculated by a quantum Monte Carlo method with the intrachain exchange constant J/k B =31.2 K and the g-value g=2.02 which are comparable to reported values (J/k B =34.8±1.6 K and g=2.04±0.04).
Energy Technology Data Exchange (ETDEWEB)
Pasrija, Kanika, E-mail: kanikapasrija@iisermohali.ac.in; Kumar, Sanjeev, E-mail: sanjeev@iisermohali.ac.in [Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Manauli PO 140306 (India)
2016-05-06
We present a Monte Carlo simulation study of a bilinear-biquadratic Heisenberg model on a two-dimensional square lattice in the presence of an external magnetic field. The study is motivated by the relevance of this simple model to the non-collinear magnetism and the consequent ferroelectric behavior in the recently discovered high-temperature multiferroic, cupric oxide (CuO). We show that an external magnetic field stabilizes a non-coplanar magnetic phase, which is characterized by a finite ferromagnetic moment along the direction of the applied magnetic field and a spiral spin texture if projected in the plane perpendicular to the magnetic field. Real-space analysis highlights a coexistence of non-collinear regions with ferromagnetic clusters. The results are also supported by simple variational calculations.
Towards exact solutions of the non-linear Heisenberg-Pauli-Weyl spinor equation
International Nuclear Information System (INIS)
Mielke, E.W.
1980-03-01
In ''color geometrodynamics'' fundamental spinor fields are assumed to obey a GL(2f,C) x GL(2c,C) gauge-invariant nonlinear spinor equation of the Heisenberg-Pauli-Weyl type. Quark confinement, assimilating a scheme of Salam and Strathdee, is (partially) mediated by the tensor ''gluons'' of strong gravity. This hypothesis is incorporated into the model by considering the nonlinear Dirac equation in a curved space-time of hadronic dimensions. Disregarding internal degrees of freedom, it is then feasible, for a particular background space-time, to obtain exact solutions of the spherical bound-state problem. Finally, these solutions are tentatively interpreted as droplet-type solitons and remarks on their interrelation with Wheeler's geon construction are made. (author)
Block spins and chirality in Heisenberg model on Kagome and triangular lattices
International Nuclear Information System (INIS)
Subrahmanyam, V.
1994-01-01
The spin-1/2 Heisenberg model (HM) is investigated using a block-spin renormalization approach on Kagome and triangular lattices. In both cases, after coarse graining the triangles on original lattice and truncation of the Hilbert space to the triangular ground state subspace, HM reduces to an effective model on a triangular lattice in terms of the triangular-block degrees of freedom viz. the spin and the chirality quantum numbers. The chirality part of the effective Hamiltonian captures the essential difference between the two lattices. It is seen that simple eigenstates can be constructed for the effective model whose energies serve as upper bounds on the exact ground state energy of HM, and chiral ordered variational states have high energies compared to the other variational states. (author). 12 refs, 2 figs
arXiv Topology in the 2d Heisenberg Model under Gradient Flow
Sandoval, Ilya O.; de Forcrand, Philippe; Gerber, Urs; Mejía-Díaz, Héctor
2017-10-28
The 2d Heisenberg model — or 2d O(3) model — is popular in condensed matter physics, and in particle physics as a toy model for QCD. Along with other analogies, it shares with 4d Yang-Mills theories, and with QCD, the property that the configurations are divided in topological sectors. In the lattice regularisation the topological charge Q can still be defined such that $Q\\in \\mathbb{Z}$. It has generally been observed, however, that the topological susceptibility ${{\\chi }_{t}}=\\langle {{Q}^{2}}\\rangle /V$ does not scale properly in the continuum limit, i.e. that the quantity ${{\\chi }_{t}}{{\\xi }^{2}}$ diverges for ξ → ∞ (where ξ is the correlation length in lattice units). Here we address the question whether or not this divergence persists after the application of the Gradient Flow.
International Nuclear Information System (INIS)
Ledue, D.; Berche, P.E.; Patte, R.
2004-01-01
We investigate the thermal-activated magnetisation reversal in a single ferromagnetic nanoparticle with uniaxial anisotropy using Monte Carlo simulations. The aim of this work is to reproduce the reversal magnetisation by uniform rotation at very low temperature in the high-energy barrier hypothesis, that is to realize the Neel-Brown model. For this purpose we have considered a simple cubic nanoparticle where each site is occupied by a classical Heisenberg spin. The Hamiltonian is the sum of an exchange interaction term, a single-ion anisotropy term and a Zeeman interaction term. Our numerical data of the thermal variation of the switching field are compared to an approximated expression and previous experimental results on Co nanoparticles
Exploring entropic uncertainty relation in the Heisenberg XX model with inhomogeneous magnetic field
Huang, Ai-Jun; Wang, Dong; Wang, Jia-Ming; Shi, Jia-Dong; Sun, Wen-Yang; Ye, Liu
2017-08-01
In this work, we investigate the quantum-memory-assisted entropic uncertainty relation in a two-qubit Heisenberg XX model with inhomogeneous magnetic field. It has been found that larger coupling strength J between the two spin-chain qubits can effectively reduce the entropic uncertainty. Besides, we observe the mechanics of how the inhomogeneous field influences the uncertainty, and find out that when the inhomogeneous field parameter b1. Intriguingly, the entropic uncertainty can shrink to zero when the coupling coefficients are relatively large, while the entropic uncertainty only reduces to 1 with the increase of the homogeneous magnetic field. Additionally, we observe the purity of the state and Bell non-locality and obtain that the entropic uncertainty is anticorrelated with both the purity and Bell non-locality of the evolution state.
Signatures of Dirac Cones in a DMRG Study of the Kagome Heisenberg Model
Directory of Open Access Journals (Sweden)
Yin-Chen He
2017-07-01
Full Text Available The antiferromagnetic spin-1/2 Heisenberg model on a kagome lattice is one of the most paradigmatic models in the context of spin liquids, yet the precise nature of its ground state is not understood. We use large-scale density matrix renormalization group simulations (DMRG on infinitely long cylinders and find indications for the formation of a gapless Dirac spin liquid. First, we use adiabatic flux insertion to demonstrate that the spin gap is much smaller than estimated from previous DMRG simulation. Second, we find that the momentum-dependent excitation spectrum, as extracted from the DMRG transfer matrix, exhibits Dirac cones that match those of a π-flux free-fermion model [the parton mean-field ansatz of a U(1 Dirac spin liquid].
133Cs NMR investigation of 2D frustrated Heisenberg antiferromagnet, Cs2CuCl4
Vachon, M.-A.; Kundhikanjana, W.; Straub, A.; Mitrovic, V. F.; Reyes, A. P.; Kuhns, P.; Coldea, R.; Tylczynski, Z.
2006-10-01
We report 133Cs nuclear magnetic resonance (NMR) measurements on the 2D frustrated Heisenberg antiferromagnet Cs2CuCl4 down to 2 K and up to 15 T. We show that 133Cs NMR is a good probe of the magnetic degrees of freedom in this material. Cu spin degrees of freedom are sensed through a strong anisotropic hyperfine coupling. The spin excitation gap opens above the critical saturation field. The gap value was determined from the activation energy of the nuclear spin-lattice relaxation rate in a magnetic field applied parallel to the Cu chains (\\skew3\\hat{b} axis). The values of the g-factor and the saturation field are consistent with the neutron-scattering and magnetization results. The measurements of the spin spin relaxation time are exploited to show that no structural changes occur down to the lowest temperatures investigated.
Scaling behavior of spin gap of the bond alternating anisotropic spin-1/2 Heisenberg chain
Energy Technology Data Exchange (ETDEWEB)
Paul, Susobhan, E-mail: suso.phy.paul@gmail.com [Department of Physics, Scottish Church College, 1 & 3 Urquhart Square, Kolkata-700006 (India); Ghosh, Asim Kumar, E-mail: asimkumar96@yahoo.com [Department of Physics, Jadavpur University, 188 Raja S C Mallik Road, Kolkata-700032 (India)
2016-05-06
Scaling behavior of spin gap of a bond alternating spin-1/2 anisotropic Heisenberg chain has been studied both in ferromagnetic (FM) and antiferromagnetic (AFM) cases. Spin gap has been estimated by using exact diagonalization technique. All those quantities have been obtained for a region of anisotropic parameter Δ defined by 0≤Δ≤1. Spin gap is found to develop as soon as the non-uniformity in the alternating bond strength is introduced in the AFM regime which furthermore sustains in the FM regime as well. Scaling behavior of the spin gap has been studied by introducing scaling exponent. The variation of scaling exponents with Δ is fitted with a regular function.
Heisenberg saturation of the Froissart bound from AdS-CFT
International Nuclear Information System (INIS)
Kang, Kyungsik; Nastase, Horatiu
2005-01-01
In a previous paper, we have analyzed high energy QCD from AdS-CFT and proved the saturation of the Froissart bound (a purely QCD proof of which is still lacking). In this Letter we describe the calculation in more physical terms and map it to QCD language. We find a remarkable agreement with the 1952 Heisenberg description of the saturation (pre-QCD!) in terms of shockwave collisions of pion field distributions. It provides a direct map between gauge theory physics and the gravitational physics on the IR brane of the Randall-Sundrum model. Saturation occurs through black hole production on the IR brane, which is in QCD production of a nonlinear pion field soliton of a Born-Infeld action in the hadron collision, that decays into free pions
International Nuclear Information System (INIS)
Starykh, O.; Singh, R.; Sandvik, A.
1997-01-01
Low temperature dynamics of the S=(1)/(2) Heisenberg chain is studied via a simple ansatz generalizing the conformal mapping and analytic continuation procedures to correlation functions with multiplicative logarithmic factors. Closed form expressions for the dynamic susceptibility and the NMR relaxation rates 1/T 1 and 1/T 2G are obtained, and are argued to improve the agreement with recent experiments. Scaling in q/T and ω/T are violated due to these logarithmic terms. Numerical results show that the logarithmic corrections are very robust. While not yet in the asymptotic low temperature regime, they provide striking qualitative confirmation of the theoretical results. copyright 1997 The American Physical Society
Solving the η-problem in hybrid inflation with Heisenberg symmetry and stabilized modulus
International Nuclear Information System (INIS)
Antusch, Stefan; Dutta, Koushik; Kostka, Philipp M.; Bastero-Gil, Mar; King, Steve F.
2009-01-01
We propose a class of models in which the η-problem of supersymmetric hybrid inflation is resolved using a Heisenberg symmetry, where the associated modulus field is stabilized and made heavy with the help of the large vacuum energy during inflation without any fine-tuning. The proposed class of models is well motivated both from string theory considerations, since it includes the commonly encountered case of no-scale supergravity Kähler potential, and from the perspective of particle physics since a natural candidate for the inflaton in this class of models is the right-handed sneutrino which is massless during the inflationary epoch, and subsequently acquires a large mass at the end of inflation. We study a specific example motivated by sneutrino hybrid inflation with no-scale supergravity in some detail, and show that the spectral index may lie within the latest WMAP range, while the tensor-to-scalar ratio is very small
Neutron Scattering from the Heisenberg Ferromagnets EuO and EuS
DEFF Research Database (Denmark)
Dietrich, O. W.; Als-Nielsen, Jens Aage; Passell, L.
1976-01-01
Inelastic neutron scattering has been used to investigate the spin dynamics of the isotropic Heisenberg ferromagnet EuO over a wide range of wave vectors and over a temperature range extending from 0.14 to 1.9TC. Below the ordering temperature spin-wave renormalization is found to agree well...... with the predictions of Dyson-Maleev theory (including the dynamical but not the kinematical interaction) when both exchange and dipolar couplings between the Eu2+ ions are taken into account. At temperatures near TC broadening of the spin-wave lines was observed. For hydrodynamic spin waves, the wave......-vector dependence of the linewidths is found to be consistent with the expectations of microscopic spin-wave theory and the temperature dependence with predictions based on dynamical scaling. At TC, linewidths were found to deviate from the q5/2 wave-vector dependence expected on the basis of dynamical scaling...
International Nuclear Information System (INIS)
Barut, A.O.; Salamin, Y.I.
1989-07-01
We present a simple approach to the relativistic calculation of the rates of spontaneous emission starting from the Heisenberg picture formula for the power radiated by a charged particle undergoing acceleration, and evaluate atomic decay rates using relativistic Dirac-Coulomb wavefunctions. The spin of the electron, embedded in its relativistic wavefunction, is shown to correctly provide the two polarization states of the emitted radiation. We discuss selection rules and calculate the Hydrogen 2 P → 1 S transition rate, among others, to be Γ = (6.2650 ± 0.0007)x10 8 s -1 in good agreement with the full field theory calculation as well as with experiment. (author). 14 refs
Degenerate and chiral states in the extended Heisenberg model on the kagome lattice
Gómez Albarracín, F. A.; Pujol, P.
2018-03-01
We present a study of the low-temperature phases of the antiferromagnetic extended classical Heisenberg model on the kagome lattice, up to third-nearest neighbors. First, we focus on the degenerate lines in the boundaries of the well-known staggered chiral phases. These boundaries have either semiextensive or extensive degeneracy, and we discuss the partial selection of states by thermal fluctuations. Then, we study the model under an external magnetic field on these lines and in the staggered chiral phases. We pay particular attention to the highly frustrated point, where the three exchange couplings are equal. We show that this point can be mapped to a model with spin-liquid behavior and nonzero chirality. Finally, we explore the effect of Dzyaloshinskii-Moriya (DM) interactions in two ways: a homogeneous and a staggered DM interaction. In both cases, there is a rich low-temperature phase diagram, with different spontaneously broken symmetries and nontrivial chiral phases.
Optimal Control for Fast and Robust Generation of Entangled States in Anisotropic Heisenberg Chains
Zhang, Xiong-Peng; Shao, Bin; Zou, Jian
2017-05-01
Motivated by some recent results of the optimal control (OC) theory, we study anisotropic XXZ Heisenberg spin-1/2 chains with control fields acting on a single spin, with the aim of exploring how maximally entangled state can be prepared. To achieve the goal, we use a numerical optimization algorithm (e.g., the Krotov algorithm, which was shown to be capable of reaching the quantum speed limit) to search an optimal set of control parameters, and then obtain OC pulses corresponding to the target fidelity. We find that the minimum time for implementing our target state depending on the anisotropy parameter Δ of the model. Finally, we analyze the robustness of the obtained results for the optimal fidelities and the effectiveness of the Krotov method under some realistic conditions.
Johnson; Thywissen; Dekker; Berggren; Chu; Younkin; Prentiss
1998-06-05
The spatially dependent de-excitation of a beam of metastable argon atoms, traveling through an optical standing wave, produced a periodic array of localized metastable atoms with position and momentum spreads approaching the limit stated by the Heisenberg uncertainty principle. Silicon and silicon dioxide substrates placed in the path of the atom beam were patterned by the metastable atoms. The de-excitation of metastable atoms upon collision with the surface promoted the deposition of a carbonaceous film from a vapor-phase hydrocarbon precursor. The resulting patterns were imaged both directly and after chemical etching. Thus, quantum-mechanical steady-state atom distributions can be used for sub-0.1-micrometer lithography.
Boukahil, A.; Huber, D. L.
1989-09-01
The harmonic magnon modes in a one-dimensional Heisenberg spin glass having nearest-neighbor exchange interactions of fixed magnitude and random sign are investigated. The Lyapounov exponent is calculated for chains of 107-108 spins over the interval 0Stinchcombe and Pimentel using transfer-matrix techniques; at higher frequencies, gaps appear in the spectrum. At low frequencies, the localization length diverges as ω-2/3. A formal connection is established between the spin glass and the one-dimensional discretized Schrödinger equation. By making use of the connection, it is shown that the theory of Derrida and Gardner, which was developed for weak potential disorder, can account quantitatively for the distribution and localization of the low-frequency magnon modes in the spin-glass model.
Magnetization process and low-temperature thermodynamics of a spin-1/2 Heisenberg octahedral chain
Strečka, Jozef; Richter, Johannes; Derzhko, Oleg; Verkholyak, Taras; Karľová, Katarína
2018-05-01
Low-temperature magnetization curves and thermodynamics of a spin-1/2 Heisenberg octahedral chain with the intra-plaquette and monomer-plaquette interactions are examined within a two-component lattice-gas model of hard-core monomers, which takes into account all low-lying energy modes in a highly frustrated parameter space involving the monomer-tetramer, localized many-magnon and fully polarized ground states. It is shown that the developed lattice-gas model satisfactorily describes all pronounced features of the low-temperature magnetization process and the magneto-thermodynamics such as abrupt changes of the isothermal magnetization curves, a double-peak structure of the specific heat or a giant magnetocaloric effect.
Applications of the representation of the Heisenberg-Euler Lagrangian by means of special functions
International Nuclear Information System (INIS)
Valluri, S.R.; Lamm, D.R.; Mielniczuk, W.J.
1993-01-01
A convenient series representation for the real part of the Heisenberg-Euler Lagrangian density of quantum electrodynamics for arbitrary nonvanishing electric fields, E, and magnetic fields, B, has been previously provided by Mielniczuk. Using this representation, numerical information for the Lagrangian is presented for the range 0 cr ≤ 5 and 0 cr ≤ 10 (subscript cr stands for critical) with the electric and magnetic fields parallel and E cr ∼ 1.7 X 10 16 V cm -1 and B cr ∼ 4.4 X 10 13 G. It was found that for a fixed electric field, the Lagrangian is monotonically increasing with increasing magnetic field strength. However, for a fixed magnetic field, the Lagrangian exhibits a positively valued maximum before turning monotonically decreasing with increasing electric field strength. Further, the series representation is extended to the case of vanishing electric or magnetic field. Numerical results for these special cases are in very close agreement with previous results, which indicated a maximum value for the Lagrangian density for B = 0 at E/E cr ∼ 3. Also, the techniques developed for deriving the real part of the Heisenberg-Euler Lagrangian are applied to the imaginary part to deduce a similar, convenient series representation that agrees with the previous results derived by others for the special case of a vanishing magnetic field. Possible applications of this Lagrangian to quantum chromodynamics are discussed. This series representation will be of use in calculations of a quantum-electrodynamical field energy density in the absence of real charges, and for calculations of polarization and magnetization of the vacuum. More accurate calculations of the cross-section scattering of light by light in the presence of a constant, homogeneous magnetic and (or) electric field are possible with the aid of this series representation. (author)
Large-scale calculation of ferromagnetic spin systems on the pyrochlore lattice
Energy Technology Data Exchange (ETDEWEB)
Soldatov, Konstantin, E-mail: soldatov_ks@students.dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Nefedev, Konstantin, E-mail: nefedev.kv@dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok (Russian Federation); Komura, Yukihiro [CIJ-solutions, Chuo-ku, Tokyo 103-0023 (Japan); Okabe, Yutaka, E-mail: okabe@phys.se.tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan)
2017-02-19
We perform the high-performance computation of the ferromagnetic Ising model on the pyrochlore lattice. We determine the critical temperature accurately based on the finite-size scaling of the Binder ratio. Comparing with the data on the simple cubic lattice, we argue the universal finite-size scaling. We also calculate the classical XY model and the classical Heisenberg model on the pyrochlore lattice. - Highlights: • Calculations of the ferromagnetic models on the pyrochlore lattice were performed. • Precise critical temperatures were determined using Binder ratio finite-size scaling. • The universal finite-size scaling was argued.
XY vs X Mixer in Quantum Alternating Operator Ansatz for Optimization Problems with Constraints
Wang, Zhihui; Rubin, Nicholas; Rieffel, Eleanor G.
2018-01-01
Quantum Approximate Optimization Algorithm, further generalized as Quantum Alternating Operator Ansatz (QAOA), is a family of algorithms for combinatorial optimization problems. It is a leading candidate to run on emerging universal quantum computers to gain insight into quantum heuristics. In constrained optimization, penalties are often introduced so that the ground state of the cost Hamiltonian encodes the solution (a standard practice in quantum annealing). An alternative is to choose a mixing Hamiltonian such that the constraint corresponds to a constant of motion and the quantum evolution stays in the feasible subspace. Better performance of the algorithm is speculated due to a much smaller search space. We consider problems with a constant Hamming weight as the constraint. We also compare different methods of generating the generalized W-state, which serves as a natural initial state for the Hamming-weight constraint. Using graph-coloring as an example, we compare the performance of using XY model as a mixer that preserves the Hamming weight with the performance of adding a penalty term in the cost Hamiltonian.
International Nuclear Information System (INIS)
Lima, R.A.T. de.
1982-01-01
Within the variational method in statistical mechanics, dynamical and thermodynamical properties of anharmonic crystal are discussed, in particular the thermal behavior of the crystalline expasion, phonons spectrum, specific heat and Debye-Weller factor (which satisfctorily describes the experimental data). Through the temperature dependent Green functions framework, dynamical and thermodynamical properties associated with the spin-Peierls transition in the magnetostrictive XY model (with one-dimensional magnetic interactions but structurally three-dimensional) are also discussed. Emphasis is given to the influence of an external magnetic field (along the z-axis) on the structural order parameter, phase diagram, specific heat, magnetization, magnetic susceptibility and phonons spectrun (acoustic and optic branches). Results are extended and new ons are exhibited such as: a) a structural Lifshitz point, which separates the uniform (U), dimerized (D) and modulated (M) phases in the T-H phase diagram; b) another special point is detected for high magnetic fields; c) the D-M first-order frontier and the metastability limits are obtained; d) for high elastic constants, fixed temperature and increasing magnetic field, the unusual sequence non uniform-uniform - non uniform-uniform is possible; e) the thermal dependence of the sound velocity presents a gap at the critical temperature. The present results have provided a quite satisfactory qualitative (and partially quantitative) description of the experiments on the TTF-BDT and MEM-(TCNQ) 2 ; this fact enables us to hope that several of our predictions indeed occur in nature. (Author) [pt
Flowing states and vortices in the classical XY model in an external field
International Nuclear Information System (INIS)
Homma, Shigeo; Aoki, Toshizumi; Takeno, Shozo.
1981-01-01
Uniformly flowing states and vortices in the classical XY model in an external field are studied. This is done by using a continuum approximation and by paying attention to particular solutions to nonlinear partial differential equations for two angles theta and phi of rotation of spins for which phi satisfies the Laplace equation. For these two states equations for theta have forms similar to that in the classical Ising model in a transverse field. The uniformly flowing states are therefore described by kink-type excitations identical to those in the two-dimensional Ising model. Phonon modes associated with the uniformly flowing states are also studied, which are similar to Bogoliubov phonons. Vortex solutions and vortex formation energy are studied in close similarity to the case of liquid He 4 . By comparing the energies of these two states, an expression for critical velocity is obtained. By making correspondence to the case of liquid He 4 , numerical values of the critical velocity and of the velocity of phonons around the uniformly flowing states are estimated. For the former the numerical value is in fair agreement with experimental data. (author)
Transfer of stem cells carrying engineered chromosomes with XY clone laser system.
Sinko, Ildiko; Katona, Robert L
2011-01-01
Current transgenic technologies for gene transfer into the germline of mammals cause a random integration of exogenous naked DNA into the host genome that can generate undesirable position effects as well as insertional mutations. The vectors used to generate transgenic animals are limited by the amount of foreign DNA they can carry. Mammalian artificial chromosomes have large DNA-carrying capacity and ability to replicate in parallel with, but without integration into, the host genome. Hence they are attractive vectors for transgenesis, cellular protein production, and gene therapy applications as well. ES cells mediated chromosome transfer by conventional blastocyst injection has a limitation in unpredictable germline transmission. The demonstrated protocol of laser-assisted microinjection of artificial chromosome containing ES cells into eight-cell mouse embryos protocol described here can solve the problem for faster production of germline transchromosomic mice.
Chauhan, V; Dada, R; Jain, V
2017-11-01
Retraction: 'Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre' by Vasundhera Chauhan, Rima Dada, Vandana Jain The above article, published online on 8 August 2016 in Wiley Online Library (http://wileyonlinelibrary.com), has been retracted by agreement between the authors, the Journal Editors-in-Chief, Wolf-Bernhard Schill and Ralf Henkel, and Blackwell Verlag GmbH. The retraction has been agreed as the result of an unresolved dispute between the first author and a colleague research fellow due to the inclusion of data from patients who were simultaneously enrolled in two studies being conducted separately by the two parties. Reference Chauhan, V., Dada, R. and Jain, V. (2016), Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre. Andrologia. doi:10.1111/and.12663. © 2016 Blackwell Verlag GmbH.
Nishina-Uchida, Noriko; Fukuzawa, Ryuji; Ishii, Tomohiro; Anaka, Matthew R; Hasegawa, Tomonobu; Hasegawa, Yukihiro
2016-01-01
Individuals with a 46,XX/46,XY karyotype are categorized as ovotesticular disorder of sexual development (ODSD) and have gonads with either an ovary on one side and a testis on the other side or a mixed ovotestis. To examine the distribution of 46,XX and 46,XY cells in gonads of 3 patients with ODSD, FISH for X and Y chromosomes and immunohistochemistry for SOX9 and FOXL2 were carried out. FISH analysis showed that XX signals were present in Sertoli cells in the seminiferous tubules, while cells containing Y signals were seen in epithelia of ovarian follicles. The immunolabeling of SOX9 and FOXL2 in the seminiferous tubules and ovarian follicles was mutually exclusive, irrespective of the presence of reversed sex chromosomes. We therefore suggest that the fate of individual gonadal epithelial cells is determined not only by the sex chromosomes but also by local environmental factors. © 2016 S. Karger AG, Basel.
Diffusion-accelerated solution of the 2-D x-y Sn equations with linear-bilinear nodal differencing
International Nuclear Information System (INIS)
Wareing, T.A.; Walters, W.F.; Morel, J.E.
1994-01-01
Recently a new diffusion-synthetic acceleration scheme was developed for solving the 2-D S n Equations in x-y geometry with bilinear-discontinuous finite element spatial discretization using a bilinear-discontinuous diffusion differencing scheme for the diffusion acceleration equations. This method differs from previous methods in that it is conditional efficient for problems with isotropic or nearly isotropic scattering. We have used the same bilinear-discontinuous diffusion scheme, and associated solution technique, to accelerate the x-y geometry S n equations with linear-bilinear nodal spatial differencing. We find that this leads to an unconditionally efficient solution method for problems with isotropic or nearly isotropic scattering. computational results are given which demonstrate this property
International Nuclear Information System (INIS)
Mukhamedov, Farrukh; Saburov, Mansoor
2010-06-01
In the present paper we study forward Quantum Markov Chains (QMC) defined on a Cayley tree. Using the tree structure of graphs, we give a construction of quantum Markov chains on a Cayley tree. By means of such constructions we prove the existence of a phase transition for the XY-model on a Cayley tree of order three in QMC scheme. By the phase transition we mean the existence of two distinct QMC for the given family of interaction operators {K }. (author)
Energy Technology Data Exchange (ETDEWEB)
Rechenberg, Helmut [MPI fuer Physik, Muenchen (Germany). Werner-Heisenberg-Institut
2010-07-01
With his discovery that measuring values of complementary fundamental quantities in the microscopic world cannot by arbitrarily precisely determined cutted Werner Heisenberg the Gordian knot for the finishing of quantum theory developed by Planck, Einstein, and others and opened by this a new ''golden era'' in the physics of the 20th century. On the base of the documents from his life and work, i. e. deeds, letters and reports of contemporaries, as well as the published and unpublished essays, books, and articles of Heisenberg - also the later on found, publications or manuscripts mainly coming from the inheritance - resulted this systematic biography of Heisenberg. The author, the last doctoral candidate of Heisenberg relied furthermore on factual and personal knowledges, mainly own remembrances on his doctoral father and his teachers, colleagues, and students. Because of the interest of an authentical biography of the theoretical physicist Heisenberg the presentation of the mathematical approaches and the corresponding derivations could not completely be abandoned. This biography appeals by this both to a scientifically cultivated as a wider in science interested audience and covers the first phase of Heisenberg's life until his Nobel price 1933. [German] Mit seiner Entdeckung, dass sich Messwerte komplementaerer Groessen in der mikroskopischen Welt nicht beliebig genau bestimmen lassen, durchschnitt Werner Heisenberg den Gordischen Knoten zur Vollendung der von Planck, Einstein und anderen entwickelten Quantentheorie und eroeffnete damit ein neues ''goldenes Zeitalter'' in der Physik des 20. Jahrhunderts. Auf der Grundlage der Dokumente aus seinem Leben und Wirken, d.h. der Urkunden, Briefe und Berichte von Zeitzeugen sowie der publizierten und unpublizierten Abhandlungen, Buecher und Artikel Heisenbergs - auch der spaeter aufgefundenen, ueberwiegend aus dem Nachlass Heisenbergs stammenden Veroeffentlichungen oder
Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}: A new telluro-phosphate with S=1/2 Heisenberg chain
Energy Technology Data Exchange (ETDEWEB)
Xia, Mingjun [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Shipeng; Lu, Jun; Sun, Young [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, R.K., E-mail: rkli@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)
2015-10-15
A new telluro-phosphate compound Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} with S=1/2 Heisenberg chain has been successfully synthesized by solid state reaction and grown by flux method. Single crystal X-ray diffraction reveals that Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} crystallizes into a monoclinic space group C2/c and cell parameters of a=17.647(3) Å, b=7.255(2) Å, c=9.191(2) Å and β=100.16 (3)°. In the structure of Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, one dimensional [CuTePO{sub 7}]{sup 3−} chains are formed by tetrahedral PO{sub 4} and trigonal bi-pyramidal TeO{sub 4} joining square planar CuO{sub 4} groups. Those [CuTePO{sub 7}]{sup 3−} chains are inter-connected by sharing one oxygen atom from the TeO{sub 4} group to form two dimensional layers. Magnetic susceptibility and specific heat measurements confirm that the title compound is a model one dimensional Heisenberg antiferromagnetic chain system. - Graphical abstract: Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, containing (CuTePO{sub 7}){sup 3−} chains formed by PO{sub 4} and TeO{sub 4} joining CuO{sub 4} groups, shows typical 1D Heisenberg antiferromagnetic chain model behavior as confirmed by magnetic measurements. - Highlights: • New telluro-phosphate Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} has been grown. • It features layered structure composed of [CuTePO{sub 7}]{sup 3−} chains and TeO{sub 4} groups. • It shows the Heisenberg antiferromagnetic chain behavior. • It is transparent in the range of 1000–2500 nm with a UV absorption edge of 393 nm.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Lei; Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu
2015-10-15
Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10–50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO{sub 1.5}, UO{sub 2} and UO{sub 3} in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3} for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U{sup 5+}, U{sup 6+}, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements. - Highlights: • We synthesize, characterize Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} solid solutions (Ln = La, Y, Nd). • Formation enthalpies become more exothermic with increasing rare earth content. • Oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3}. • Direct calorimetric measurements are in good agreement with free energy data.
Wide spectrum of NR5A1‐related phenotypes in 46,XY and 46,XX individuals
Domenice, Sorahia; Machado, Aline Zamboni; Ferreira, Frederico Moraes; Ferraz‐de‐Souza, Bruno; Lerario, Antonio Marcondes; Lin, Lin; Nishi, Mirian Yumie; Gomes, Nathalia Lisboa; da Silva, Thatiana Evelin; Silva, Rosana Barbosa; Correa, Rafaela Vieira; Montenegro, Luciana Ribeiro; Narciso, Amanda; Costa, Elaine Maria Frade; Achermann, John C
2016-01-01
Steroidogenic factor 1 (NR5A1, SF‐1, Ad4BP) is a transcriptional regulator of genes involved in adrenal and gonadal development and function. Mutations in NR5A1 have been among the most frequently identified genetic causes of gonadal development disorders and are associated with a wide phenotypic spectrum. In 46,XY individuals, NR5A1‐related phenotypes may range from disorders of sex development (DSD) to oligo/azoospermia, and in 46,XX individuals, from 46,XX ovotesticular and testicular DSD to primary ovarian insufficiency (POI). The most common 46,XY phenotype is atypical or female external genitalia with clitoromegaly, palpable gonads, and absence of Müllerian derivatives. Notably, an undervirilized external genitalia is frequently seen at birth, while spontaneous virilization may occur later, at puberty. In 46,XX individuals, NR5A1 mutations are a rare genetic cause of POI, manifesting as primary or secondary amenorrhea, infertility, hypoestrogenism, and elevated gonadotropin levels. Mothers and sisters of 46,XY DSD patients carrying heterozygous NR5A1 mutations may develop POI, and therefore require appropriate counseling. Moreover, the recurrent heterozygous p.Arg92Trp NR5A1 mutation is associated with variable degrees of testis development in 46,XX patients. A clear genotype‐phenotype correlation is not seen in patients bearing NR5A1 mutations, suggesting that genetic modifiers, such as pathogenic variants in other testis/ovarian‐determining genes, may contribute to the phenotypic expression. Here, we review the published literature on NR5A1‐related disease, and discuss our findings at a single tertiary center in Brazil, including ten novel NR5A1 mutations identified in 46,XY DSD patients. The ever‐expanding phenotypic range associated with NR5A1 variants in XY and XX individuals confirms its pivotal role in reproductive biology, and should alert clinicians to the possibility of NR5A1 defects in a variety of phenotypes presenting with gonadal
Alécio, Raphael Cavalcante; Strečka, Jozef; Lyra, Marcelo L.
2018-04-01
The thermodynamic behavior of an Ising-Heisenberg triangular tube with Heisenberg intra-rung and Ising inter-rung interactions is exactly obtained in an external magnetic field within the framework of the transfer-matrix method. We report rigorous results for the temperature dependence of the magnetization, entropy, pair correlations and specific heat, as well as typical iso-entropic curves. The discontinuous field-driven ground-state phase transitions are reflected in some anomalous thermodynamic behavior as for instance a striking low-temperature peak of the specific heat and an enhanced magnetocaloric effect. It is demonstrated that the intermediate magnetization plateaus shrink in and the relevant sharp edges associated with the magnetization jump round off upon increasing temperature.
Manojlović, N.; Salom, I.
2017-10-01
The implementation of the algebraic Bethe ansatz for the XXZ Heisenberg spin chain in the case, when both reflection matrices have the upper-triangular form is analyzed. The general form of the Bethe vectors is studied. In the particular form, Bethe vectors admit the recurrent procedure, with an appropriate modification, used previously in the case of the XXX Heisenberg chain. As expected, these Bethe vectors yield the strikingly simple expression for the off-shell action of the transfer matrix of the chain as well as the spectrum of the transfer matrix and the corresponding Bethe equations. As in the XXX case, the so-called quasi-classical limit gives the off-shell action of the generating function of the corresponding trigonometric Gaudin Hamiltonians with boundary terms.
International Nuclear Information System (INIS)
Manojlović, N.; Salom, I.
2017-01-01
The implementation of the algebraic Bethe ansatz for the XXZ Heisenberg spin chain in the case, when both reflection matrices have the upper-triangular form is analyzed. The general form of the Bethe vectors is studied. In the particular form, Bethe vectors admit the recurrent procedure, with an appropriate modification, used previously in the case of the XXX Heisenberg chain. As expected, these Bethe vectors yield the strikingly simple expression for the off-shell action of the transfer matrix of the chain as well as the spectrum of the transfer matrix and the corresponding Bethe equations. As in the XXX case, the so-called quasi-classical limit gives the off-shell action of the generating function of the corresponding trigonometric Gaudin Hamiltonians with boundary terms.
Directory of Open Access Journals (Sweden)
N. Manojlović
2017-10-01
Full Text Available The implementation of the algebraic Bethe ansatz for the XXZ Heisenberg spin chain in the case, when both reflection matrices have the upper-triangular form is analyzed. The general form of the Bethe vectors is studied. In the particular form, Bethe vectors admit the recurrent procedure, with an appropriate modification, used previously in the case of the XXX Heisenberg chain. As expected, these Bethe vectors yield the strikingly simple expression for the off-shell action of the transfer matrix of the chain as well as the spectrum of the transfer matrix and the corresponding Bethe equations. As in the XXX case, the so-called quasi-classical limit gives the off-shell action of the generating function of the corresponding trigonometric Gaudin Hamiltonians with boundary terms.
International Nuclear Information System (INIS)
Zhang, Guo-Feng
2007-01-01
Thermal entanglement of a two-qubit Heisenberg chain in the presence of the Dzyaloshinski-Moriya (DM) anisotropic antisymmetric interaction and entanglement teleportation when using two independent Heisenberg chains as the quantum channel are investigated. It is found that the DM interaction can excite entanglement and teleportation fidelity. The output entanglement increases linearly with increasing value of the input; its dependences on the temperature, DM interaction, and spin coupling constant are given in detail. Entanglement teleportation will be better realized via an antiferromagnetic spin chain when the DM interaction is turned off and the temperature is low. However, the introduction of the DM interaction can cause the ferromagnetic spin chain to be a better quantum channel for teleportation. A minimal entanglement of the thermal state in the model is needed to realize the entanglement teleportation regardless of whether the spin chains are antiferromagnetic or ferromagnetic
XY sperm separation and use in artificial insemination and other ARTs.
Cran, David G
2007-01-01
Many tens of thousands of calves resulting from artificial insemination (AI) have been born worldwide after XY sperm separation and commercial production is underway in several countries. Accuracy of sex selection is some 90% and can be achieved both in research facilities and at AI studs in rural locations. Most facilities sort X- sperm which have also be utilised for superovulation and embryo transfer projects and for in vitro fertilisation (IVF) as well as AI. Sort rates of some 15 x 10(6) sperm/h are currently achievable and are used for low dose insemination, generally at 2 x 10(6) frozen sperm per dose, at a minimum of 35% post thaw motility. Pregnancy rates are some 70% to 80% of normal "high" dose unsexed inseminates. Good herd management is essential for high pregnancy rates with sexed sperm. In addition to cattle, offspring of predetermined sex have been born in the human, sheep, pig, horse, rabbit, elk, buffalo, cat and dolphin. Each species has its own challenge with regard to sperm handling and insemination procedure. In pigs, horses and sheep, the available dose of sexed sperm is very considerably lower than that which is used for conventional AI and special approaches have been devised for each species. In the pig a flexible catheter has been used to deliver a small dose of semen as close to the site of ovulation as possible. In the horse, hysteroscopic insemination at the utero tubal junction has resulted in fertilisation and, in the sheep, laparoscopic insemination into the uterus is the standard procedure for both sexed and unsexed sperm. Further advances in the efficiency of sorting together with improvements in sperm handling should result in acceptable pregnancy rates in these species.
Agnathia-holoprosencephaly associated with a 46,XY,-21,+t(21q;21q) karyotype
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Niedermeyer, K.K.; McCorquodale, M.M.; Burton, B.K. [Univ. of Illinois, Chicago, IL (United States)
1994-09-01
We report an unusual case of agnathia-holoprosencephaly associated with Down syndrome due to a 21/21 translocation. The patient presented prenatally at 21 wks gestation. A fetal ultrasound revealed multiple CNS anomalies including hydrocephalus, compressed cerebellum, absent septum pellucidum and possible cranial meningocele or encephalocele. High resolution ultrasound & fetal karyotype were recommended. The patient refused & elected to have a pregnancy termination. Chromosomal analysis performed on products of conception revealed a 46,XY,-21,+t(21q;21q) karyotype. Fluorescence in situ hybridization was performed and confirmed the 21/21 translocation chromosome. An autopsy revealed agnathia and multiple CNS anomalies including absence of the septum pellucidum, absence of the corpus callosum, arhinencephaly, an occiptal meningoencephalocele, dilation of the lateral ventricles, and extensive dysgenesis & heterotopias of the central cerebrum & mid-brain. Additional abnormalities included a persistent left superior vena cava, atrial & ventricular septal defects, irregular length of the fingers with absence of the middle phalanges of the right 2nd and 5th & left 5th digits and bilateral simian creases. Agnathia can be an isolated abnormality but often is associated with holoprosencephaly and/or situs inversus. The majority of familial case of agnathis-holoprosencephaly was caused by an inherited unbalanced translocation resulting in duplication of 6p and monosomy of 18p. Our patient had a translocation form of trisomy 21 but did not have a phenotype consistent with Down syndrome. Trisomy 21 has not been previously reported in other cases of agnathia-holoprosencephaly. Whether the chromosomal abnormality caused the phenotypic abnormalities or if it is a coincidental finding cannot be determined.
A novel mouse Fgfr2 mutant, hobbyhorse (hob, exhibits complete XY gonadal sex reversal.
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Pam Siggers
Full Text Available The secreted molecule fibroblast growth factor 9 (FGF9 plays a critical role in testis determination in the mouse. In embryonic gonadal somatic cells it is required for maintenance of SOX9 expression, a key determinant of Sertoli cell fate. Conditional gene targeting studies have identified FGFR2 as the main gonadal receptor for FGF9 during sex determination. However, such studies can be complicated by inefficient and variable deletion of floxed alleles, depending on the choice of Cre deleter strain. Here, we report a novel, constitutive allele of Fgfr2, hobbyhorse (hob, which was identified in an ENU-based forward genetic screen for novel testis-determining loci. Fgr2hob is caused by a C to T mutation in the invariant exon 7, resulting in a polypeptide with a mis-sense mutation at position 263 (Pro263Ser in the third extracellular immunoglobulin-like domain of FGFR2. Mutant homozygous embryos show severe limb and lung defects and, when on the sensitised C57BL/6J (B6 genetic background, undergo complete XY gonadal sex reversal associated with failure to maintain expression of Sox9. Genetic crosses employing a null mutant of Fgfr2 suggest that Fgr2hob is a hypomorphic allele, affecting both the FGFR2b and FGFR2c splice isoforms of the receptor. We exploited the consistent phenotype of this constitutive mutant by analysing MAPK signalling at the sex-determining stage of gonad development, but no significant abnormalities in mutant embryos were detected.
X-y interactions underlie sperm head abnormality in hybrid male house mice.
Campbell, Polly; Nachman, Michael W
2014-04-01
The genetic basis of hybrid male sterility in house mice is complex, highly polygenic, and strongly X linked. Previous work suggested that there might be interactions between the Mus musculus musculus X and the M. m. domesticus Y with a large negative effect on sperm head morphology in hybrid males with an F1 autosomal background. To test this, we introgressed the M. m. domesticus Y onto a M. m. musculus background and measured the change in sperm morphology, testis weight, and sperm count across early backcross generations and in 11th generation backcross males in which the opportunity for X-autosome incompatibilities is effectively eliminated. We found that abnormality in sperm morphology persists in M. m. domesticus Y introgression males, and that this phenotype is rescued by M. m. domesticus introgressions on the X chromosome. In contrast, the severe reductions in testis weight and sperm count that characterize F1 males were eliminated after one generation of backcrossing. These results indicate that X-Y incompatibilities contribute specifically to sperm morphology. In contrast, X-autosome incompatibilities contribute to low testis weight, low sperm count, and sperm morphology. Restoration of normal testis weight and sperm count in first generation backcross males suggests that a small number of complex incompatibilities between loci on the M. m. musculus X and the M. m. domesticus autosomes underlie F1 male sterility. Together, these results provide insight into the genetic architecture of F1 male sterility and help to explain genome-wide patterns of introgression across the house mouse hybrid zone.
Directory of Open Access Journals (Sweden)
Servant Nadège
2010-03-01
Full Text Available Abstract Background Primary amenorrhea due to 46,XY disorders of sex differentiation (DSD is a frequent reason for consultation in endocrine and gynecology clinics. Among the genetic causes of low-testosterone primary amenorrhea due to 46,XY DSD, SRY gene is reported to be frequently involved, but other genes, such as SF1 and WT1, have never been studied for their prevalence. Methods We directly sequenced SRY, SF1 and WT1 genes in 15 adolescent girls with primary amenorrhea, low testosterone concentration, and XY karyotype, to determine the prevalence of mutations. We also analyzed the LH receptor gene in patients with high LH and normal FSH concentrations. Results Among the 15 adolescents with primary amenorrhea and low testosterone concentration, we identified two new SRY mutations, five new SF1 mutations and one new LH receptor gene mutation. Our study confirms the 10-15% prevalence of SRY mutations and shows the high prevalence (33% of SF1 abnormalities in primary amenorrhea due to 46,XY DSD with low plasma testosterone concentration. Conclusions The genetic analysis of low-testosterone primary amenorrhea is complex as several factors may be involved. This work underlines the need to systematically analyze the SF1 sequence in girls with primary amenorrhea due to 46,XY DSD and low testosterone, as well as in newborns with 46,XY DSD.
Heisenberg equations of motion for the spin-3/2 field in the presence of an interaction
International Nuclear Information System (INIS)
Nagpal, A.K.
1977-01-01
The Rarita-Schwinger spin-3/2 field interacting with a Dirac field and a scalar field (external) is found to satisfy the Heisenberg equations of motion, in the weak-field limit. This is analogous to the result, for the case of spin-3/2 field minimally coupled with external electromagnetic field, recently obtained by Mainland and Sudarshan (Phys. Rev. D. 8:1088 (1973)). (author)
Comment on ‘Adjacent spin operator dynamical structure factor of the S = 1/2 Heisenberg chain’
International Nuclear Information System (INIS)
De Gier, Jan
2012-01-01
We consider the paper ‘Adjacent spin operator dynamical structure factor of the S = 1/2 Heisenberg chain’, by Klauser, Mossel and Caux (2012 J. Stat. Mech. P03012) to be a new and important step in the numerical analysis of the correlation functions of quantum spin chains. The correlation functions considered in this paper were not previously computed, their analytical study is extremely complicated and the numerical results can be used for comparison with experiments. (news and perspectives)
Exact solution of the mixed spin-1/2 and spin-S Ising-Heisenberg diamond chain
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L. Čanová
2009-01-01
Full Text Available The geometric frustration in a class of the mixed spin-1/2 and spin-S Ising-Heisenberg diamond chains is investigated by combining three exact analytical techniques: Kambe projection method, decoration-iteration transformation and transfer-matrix method. The ground state, the magnetization process and the specific heat as a function of the external magnetic field are particularly examined for different strengths of the geometric frustration. It is shown that the increase of the Heisenberg spin value S raises the number of intermediate magnetization plateaux, which emerge in magnetization curves provided that the ground state is highly degenerate on behalf of a sufficiently strong geometric frustration. On the other hand, all intermediate magnetization plateaux merge into a linear magnetization versus magnetic field dependence in the limit of classical Heisenberg spin S → ∞. The enhanced magnetocaloric effect with cooling rate exceeding the one of paramagnetic salts is also detected when the disordered frustrated phase constitutes the ground state and the external magnetic field is small enough.
International Nuclear Information System (INIS)
Senin, H.B.; Sidek, H.A.A.; Saunders, G.A.
1994-01-01
From measurements of changes in transit time of 10 MHz of ultrasonic wave as a function of temperature and hydrostatic pressure, the linear and non-linear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses with compositions near to that corresponding to the metaphosphate have been determined. For each glass the second order elastic stiffness tensor components C sub ijs (SOEC) continue to increase down to 10K in a manner consistent with phonons interactions with two level systems. Measurements of the effects of hydrostatic pressure on the ultrasonic wave velocities have been used to determine the hydrostatic pressure derivatives (dC sub ij/dP) sub T,P=0 of the SOEC and (dB0 sup s)/dP) sub T,P=0 of the bulk modulus B0 sup s at room temperature (293K). For the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses, (dC sub 11/dP), (dC sub 44/dP), and (dBo/dP), are small but positives; these glasses stiffen under pressure. The elastic behaviour of these ternary glasses lies intermediate between those of (Sm sub 2 O sub 3)(P sub 2 O sub 5) sub (1-x) and (La sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses. Replacement of the Sm sup 3+ by La sup 3+ in the ternary phosphate glasses negates the acoustic mode softening. Possible sources of the different effects of La sub 3+ and Sm sub 3+ modifiers on the nonlinear acoustic properties of metaphosphate glasses are discussed
Quantum-Wave Equation and Heisenberg Inequalities of Covariant Quantum Gravity
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Claudio Cremaschini
2017-07-01
Full Text Available Key aspects of the manifestly-covariant theory of quantum gravity (Cremaschini and Tessarotto 2015–2017 are investigated. These refer, first, to the establishment of the four-scalar, manifestly-covariant evolution quantum wave equation, denoted as covariant quantum gravity (CQG wave equation, which advances the quantum state ψ associated with a prescribed background space-time. In this paper, the CQG-wave equation is proved to follow at once by means of a Hamilton–Jacobi quantization of the classical variational tensor field g ≡ g μ ν and its conjugate momentum, referred to as (canonical g-quantization. The same equation is also shown to be variational and to follow from a synchronous variational principle identified here with the quantum Hamilton variational principle. The corresponding quantum hydrodynamic equations are then obtained upon introducing the Madelung representation for ψ , which provides an equivalent statistical interpretation of the CQG-wave equation. Finally, the quantum state ψ is proven to fulfill generalized Heisenberg inequalities, relating the statistical measurement errors of quantum observables. These are shown to be represented in terms of the standard deviations of the metric tensor g ≡ g μ ν and its quantum conjugate momentum operator.
Kim, Sanghoon
2018-04-19
Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii–Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required. Here we experimentally demonstrate the close correlation of the DMI with the anisotropy of the orbital magnetic moment and with the magnetic dipole moment of the ferromagnetic metal in addition to Heisenberg exchange. The density functional theory and the tight-binding model calculations reveal that inversion symmetry breaking with spin–orbit coupling gives rise to the orbital-related correlation. Our study provides the experimental connection between the orbital physics and the spin–orbit-related phenomena, such as DMI.
Effect of Dzyaloshinskii-Moriya on Magnetic orders of J_1-J_2 Antiferromagnetic Heisenberg model
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Fariba Masoudi
2017-11-01
Full Text Available Motivated by recent experiments that detects Dzyaloshinskii-Moriya (DM interaction in , we study the effects of DM interaction on magnetic orders of J1-J2 antiferromagnetic Heisenberg model. First, we find the classical phase diagram of the model using Luttinger-Tisza approximation. In this approximation, the classical phase diagram has two phases. For , the model has canted Neel and DM interaction cants the spins of one on the subluttices. The ground state of model is classically degenerate for , including infinit numbers of vorticity vectors that are able to minimize the model. This phase is important because of the probability of the existence of quantum spin liquid in this region. To investigate the effect of quantum fluctuation on the stability of the classical phase diagram, linear spin wave theory of Holstein-Primakoff is used. The results show that in the classical degeneracy regime, the quantum fluctuations for cause spiral order in this region. The ground state of model remains disorder for, and this region is a good place for finding quantum spin liquid
Spin wave dynamics in Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes
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Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)
2016-09-15
The spin wave dynamics, including the magnetization, spin wave dispersion relation, and energy level splitting, of Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes are systematically calculated by use of the double-time Green’s function method within the random phase approximation. The role of temperature, diameter of the tube, and wave vector on spin wave energy spectrum and energy level splitting are carefully analyzed. There are two categories of spin wave modes, which are quantized and degenerate, and the total number of independent magnon branches is dependent on diameter of the tube, caused by the physical symmetry of nanotubes. Moreover, the number of flat spin wave modes increases with diameter of the tube rising. The spin wave energy and the energy level splitting decrease with temperature rising, and become zero as temperature reaches the critical point. At any temperature, the energy level splitting varies with wave vector, and for a larger wave vector it is smaller. When pb=π, the boundary of first Brillouin zone, spin wave energies are degenerate, and the energy level splittings are zero.
Spin Hartree-Fock approach to studying quantum Heisenberg antiferromagnets in low dimensions
Werth, A.; Kopietz, P.; Tsyplyatyev, O.
2018-05-01
We construct a new mean-field theory for a quantum (spin-1/2) Heisenberg antiferromagnet in one (1D) and two (2D) dimensions using a Hartree-Fock decoupling of the four-point correlation functions. We show that the solution to the self-consistency equations based on two-point correlation functions does not produce any unphysical finite-temperature phase transition, in accord with the Mermin-Wagner theorem, unlike the common approach based on the mean-field equation for the order parameter. The next-neighbor spin-spin correlation functions, calculated within this approach, reproduce closely the strong renormalization by quantum fluctuations obtained via a Bethe ansatz in 1D and a small renormalization of the classical antiferromagnetic state in 2D. The heat capacity approximates with reasonable accuracy the full Bethe ansatz result at all temperatures in 1D. In 2D, we obtain a reduction of the peak height in the heat capacity at a finite temperature that is accessible by high-order 1 /T expansions.
Heisenberg spin-1/2 XXZ chain in the presence of electric and magnetic fields
Thakur, Pradeep; Durganandini, P.
2018-02-01
We study the interplay of electric and magnetic order in the one-dimensional Heisenberg spin-1/2 XXZ chain with large Ising anisotropy in the presence of the Dzyaloshinskii-Moriya (DM) interaction and with longitudinal and transverse magnetic fields, interpreting the DM interaction as a coupling between the local electric polarization and an external electric field. We obtain the ground state phase diagram using the density matrix renormalization group method and compute various ground state quantities like the magnetization, staggered magnetization, electric polarization and spin correlation functions, etc. In the presence of both longitudinal and transverse magnetic fields, there are three different phases corresponding to a gapped Néel phase with antiferromagnetic (AF) order, gapped saturated phase, and a critical incommensurate gapless phase. The external electric field modifies the phase boundaries but does not lead to any new phases. Both external magnetic fields and electric fields can be used to tune between the phases. We also show that the transverse magnetic field induces a vector chiral order in the Néel phase (even in the absence of an electric field) which can be interpreted as an electric polarization in a direction parallel to the AF order.
Investigation of the chiral antiferromagnetic Heisenberg model using projected entangled pair states
Poilblanc, Didier
2017-09-01
A simple spin-1/2 frustrated antiferromagnetic Heisenberg model (AFHM) on the square lattice—including chiral plaquette cyclic terms—was argued [A. E. B. Nielsen, G. Sierra, and J. I. Cirac, Nat. Commun. 4, 2864 (2013), 10.1038/ncomms3864] to host a bosonic Kalmeyer-Laughlin (KL) fractional quantum Hall ground state [V. Kalmeyer and R. B. Laughlin, Phys. Rev. Lett. 59, 2095 (1987), 10.1103/PhysRevLett.59.2095]. Here, we construct generic families of chiral projected entangled pair states (chiral PEPS) with low bond dimension (D =3 ,4 ,5 ) which, upon optimization, provide better variational energies than the KL Ansatz. The optimal D =3 PEPS exhibits chiral edge modes described by the Wess-Zumino-Witten SU(2) 1 model, as expected for the KL spin liquid. However, we find evidence that, in contrast to the KL state, the PEPS spin liquids have power-law dimer-dimer correlations and exhibit a gossamer long-range tail in the spin-spin correlations. We conjecture that these features are genuine to local chiral AFHM on bipartite lattices.