An investigation into the impact of reflective teaching on EFL learners autonomy and intrinsic motivation

Directory of Open Access Journals (Sweden)

Elahe Fallah

2015-12-01

Full Text Available This study has sought to explore the effect of reflective teaching on learner autonomy and the intrinsic motivation of Iranian upper-intermediate female learners. The subjects included 60 adult upper-intermediate EFL learners chosen out of ninety, based on the scores obtained through administration of the TOEFL exam. They were randomly assigned to two groups: a the experimental group - taught by a reflective teacher - and b the control group instructed by an unreflective teacher. The motivation questionnaire and the autonomy questionnaire were administered to both groups to make sure that the two groups were not significantly different in terms of the level of motivation and autonomy. The experimental group was then taught by the reflective teacher and the control group was taught by the unreflective teacher who adopted no tangible reflective actions. Finally, both groups sat for motivation and autonomy questionnaires. The results indicate that reflective teaching leads to the enhancement of both learners’ autonomy and the intrinsic motivation level.

Reflections on symmetries at SPIN '94

International Nuclear Information System (INIS)

Page, S.A.

1995-01-01

In my view, the parallel sessions on ''Symmetries'' were amongst the most stimulating sessions of this conference. Speakers reported on experimental tests of Charge Symmetry, Parity, and Time Reversal violation and their theoretical interpretation, spanning a wide range of energy scales and experimental techniques. I hope that this brief summary will whet the reader's appetite to explore the many contributed papers which follow

Symmetry of priapulids (Priapulida). 1. Symmetry of adults.

Science.gov (United States)

Adrianov, A V; Malakhov, V V

2001-02-01

Priapulids possess a radial symmetry that is remarkably reflected in both external morphology and internal anatomy. It results in the appearance of 25-radial (a number divisible by five) symmetry summarized as a combination of nonaradial, octaradial, and octaradial (9+8+8) symmetries of scalids. The radial symmetry is a secondary appearance considered as an evolutionary adaptation to a lifestyle within the three-dimensional environment of bottom sediment. The eight anteriormost, or primary, scalids retain their particular position because of their innervation directly from the circumpharyngeal brain. As a result of a combination of the octaradial symmetry of primary scalids, pentaradial symmetry of teeth, and the 25-radial symmetry of scalids, the initial bilateral symmetry remains characterized by the single sagittal plane. Copyright 2001 Wiley-Liss, Inc.

Optimal Spatial Harvesting Strategy and Symmetry-Breaking

International Nuclear Information System (INIS)

Kurata, Kazuhiro; Shi Junping

2008-01-01

A reaction-diffusion model with logistic growth and constant effort harvesting is considered. By minimizing an intrinsic biological energy function, we obtain an optimal spatial harvesting strategy which will benefit the population the most. The symmetry properties of the optimal strategy are also discussed, and related symmetry preserving and symmetry breaking phenomena are shown with several typical examples of habitats

Designing Reflection and Symmetry Learning by Using Math Traditional Dance in Primary School

Directory of Open Access Journals (Sweden)

Yullys Helsa

2011-01-01

Full Text Available The innovation of education is an important point of Pendidikan Matematika Realistik Indonesia (PMRI, one of them through traditional dance as a context of national cultural. Dance that collaborated with concept of mathematics, it is called Math Traditional Dance. This research aims to produce learning line (specific the material of reflection and symmetry. The research method used is design research that consisted of preparing for the experiments, teaching experiments, and retrospective analysis. Data collected through observation, interviews, documentation and field notes. This research was conducted with 22 students in MIN 2 Palembang. From the try out that is obtained from the formal to the informal learning described in the learning process, so that support learning process of mirroring and symmetry for the students in grade four in elementary school.Key words: PMRI, math traditional dance, design research, learning path, mirroring and symmetry DOI: http://dx.doi.org/10.22342/jme.2.1.782.79-94

Designing Reflection and Symmetry Learning by Using Math Traditional Dance in Primary School

Directory of Open Access Journals (Sweden)

Yullys Helsa

2011-01-01

Full Text Available The innovation of education is an important point of Pendidikan Matematika Realistik Indonesia (PMRI, one of them through traditional dance as a context of national cultural. Dance that collaborated with concept of mathematics, it is called Math Traditional Dance. This research aims to produce learning line (specific the material of reflection and symmetry. The research method used is design research that consisted of preparing for the experiments, teaching experiments, and retrospective analysis. Data collected through observation, interviews, documentation and field notes. This research was conducted with 22 students in MIN 2 Palembang. From the try out that is obtained from the formal to the informal learning described in the learning process, so that support learning process of mirroring and symmetry for the students in grade four in elementary school.

Reversible unidirectional reflection and absorption of PT-symmetry structure under electro-optical modulation

Science.gov (United States)

Fang, Yun-tuan; Zhang, Yi-chi; Xia, Jing

2018-06-01

In order to obtain tunable unidirectional device, we assumed an ideal periodic layered Parity-Time (PT) symmetry structure inserted by doped LiNbO3 (LN) interlayers. LN is a typical electro-optical material of which the refractive index depends on the external electric field. In our work, we theoretically investigate the modulation effect of the external electric field on the transmittance and reflectance of the structure through numerical method. Through selected structural parameters, the one-way enhanced reflection and high absorption (above 0.9) behaviors are found. Within a special frequency band (not a single frequency), our theoretical model performs enhanced reflection in one incidence direction and high absorption in the other direction. Furthermore, the directions of enhanced reflection and absorption can be reversed through reversing the direction of applied electric field. Such structure with reversible properties has the potential in designing new optical devices.

Shape analysis with subspace symmetries

KAUST Repository

Berner, Alexander

2011-04-01

We address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising. © 2010 The Author(s).

Role of symmetry-breaking induced by Er × B shear flows on developing residual stresses and intrinsic rotation in the TEXTOR tokamak

International Nuclear Information System (INIS)

Xu, Y.; Shesterikov, I.; Berte, M.; Dumortier, P.; Van Schoor, M.; Vergote, M.; Hidalgo, C.; Krämer-Flecken, A.; Koslowski, R.

2013-01-01

Direct measurements of residual stress (force) have been executed at the edge of the TEXTOR tokamak using multitip Langmuir and Mach probes, together with counter-current NBI torque to balance the existing toroidal rotation. Substantial residual stress and force have been observed at the plasma boundary, confirming the existence of a finite residual stress as possible mechanisms to drive the intrinsic toroidal rotation. In low-density discharges, the residual stress displays a quasi-linear dependence on the local pressure gradient, consistent with theoretical predictions. At high-density shots the residual stress and torque are strongly suppressed. The results show close correlation between the residual stress and the E r × B flow shear rate, suggesting a minimum threshold of the E × B flow shear required for the k ∥ symmetry breaking. These findings provide the first experimental evidence of the role of E r × B sheared flows in the development of residual stresses and intrinsic rotation. (letter)

Duality and self-duality (energy reflection symmetry) of quasi-exactly solvable periodic potentials

International Nuclear Information System (INIS)

Dunne, Gerald V.; Shifman, M.

2002-01-01

A class of spectral problems with a hidden Lie-algebraic structure is considered. We define a duality transformation which maps the spectrum of one quasi-exactly solvable (QES) periodic potential to that of another QES periodic potential. The self-dual point of this transformation corresponds to the energy-reflection symmetry found previously for certain QES systems. The duality transformation interchanges bands at the bottom (top) of the spectrum of one potential with gaps at the top (bottom) of the spectrum of the other, dual, potential. Thus, the duality transformation provides an exact mapping between the weak coupling (perturbative) and semiclassical (nonperturbative) sectors

Nd:YAG-laser-based time-domain reflectometry measurements of the intrinsic reflection signature from PMMA fiber splices

Science.gov (United States)

Lawson, Christopher M.; Michael, Robert R., Jr.; Dressel, Earl M.; Harmony, David W.

1991-12-01

Optical time domain reflectometry (OTDR) measurements have been performed on polished polymethylmethacrylate (PMMA) plastic fiber splices. After the dominant splice reflection sources due to surface roughness, inexact index matching, and fiber core misalignment were eliminated, an intrinsic OTDR signature 3 - 8 dB above the Rayleigh backscatter floor remained with all tested fibers. This minimum splice reflectivity exhibits characteristics that are consistent with sub-surface polymer damage and can be used for detection of PMMA fiber splices.

Mirror symmetry

CERN Document Server

Voisin, Claire

1999-01-01

This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...

Direct transitions among atomic states of negative reflection symmetry in the scattering plane: Li(2p0,3p0,3d±1)-He collisions

International Nuclear Information System (INIS)

Nielsen, S.E.; Andersen, N.

1988-01-01

This paper reports coupled channel model calculations of direct transitions in Li-He collisions among excited Li-states of negative reflection symmetry in the scattering plane. Using the natural coordinate frame, transition probabilities and orientation and alignment parameters are predicted as functions of impact energy and impact parameter for various initial states. It is found that for geometrical reasons transition probabilities are one to two orders of magnitude smaller than for corresponding states with positive reflection symmetry. Some experimental consequences of this finding are pointed out. (orig.)

Discovery of Intrinsic Primitives on Triangle Meshes

KAUST Repository

Solomon, Justin

2011-04-01

The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost-isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently-developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state-of-the-art methods using the Princeton Segmentation Benchmark. © 2011 The Author(s).

Reflections on the four facets of symmetry: how physics exemplifies rational thinking

Science.gov (United States)

Mouchet, Amaury

2013-12-01

In contemporary theoretical physics, the powerful notion of symmetry stands for a web of intricate meanings among which I identify four clusters associated with the notion of transformation, comprehension, invariance and projection. While their interrelations are examined closely these four facets of symmetry are scrutinised one after the other in great detail. This decomposition allows us to carefully examine the multiple different roles symmetry plays in many places in physics. Furthermore, some connections with other disciplines like neurobiology, epistemology, cognitive sciences and, not least, philosophy are proposed in an attempt to show that symmetry can be an organising principle also in these fields.

Symmetry, Wigner functions and particle reactions

International Nuclear Information System (INIS)

Chavlejshvili, M.P.

1994-01-01

We consider the great principle of physics - symmetry - and some ideas, connected with it, suggested by a great physicist Eugene Wigner. We will discuss the concept of symmetry and spin, study the problem of separation of kinematics and dynamics in particle reactions. Using Wigner rotation functions (reflecting symmetry properties) in helicity amplitude decomposition and crossing-symmetry between helicity amplitudes (which contains the same Wigner functions) we get convenient general formalism for description of reactions between particles with any masses and spins. We also consider some applications of the formalism. 17 refs., 1 tab

Effective field theory of emergent symmetry breaking in deformed atomic nuclei

International Nuclear Information System (INIS)

Papenbrock, T; Weidenmüller, H A

2015-01-01

Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. We extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. In deformed nuclei these are vibrational modes each of which serves as band head of a rotational band. (paper)

Intrinsic rotation with gyrokinetic models

International Nuclear Information System (INIS)

Parra, Felix I.; Barnes, Michael; Catto, Peter J.; Calvo, Iván

2012-01-01

The generation of intrinsic rotation by turbulence and neoclassical effects in tokamaks is considered. To obtain the complex dependences observed in experiments, it is necessary to have a model of the radial flux of momentum that redistributes the momentum within the tokamak in the absence of a preexisting velocity. When the lowest order gyrokinetic formulation is used, a symmetry of the model precludes this possibility, making small effects in the gyroradius over scale length expansion necessary. These effects that are usually small become important for momentum transport because the symmetry of the lowest order gyrokinetic formulation leads to the cancellation of the lowest order momentum flux. The accuracy to which the gyrokinetic equation needs to be obtained to retain all the physically relevant effects is discussed.

Unified flavor symmetry from warped dimensions

Energy Technology Data Exchange (ETDEWEB)

Frank, Mariana, E-mail: mariana.frank@concordia.ca [Department of Physics, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6 (Canada); Hamzaoui, Cherif, E-mail: hamzaoui.cherif@uqam.ca [Groupe de Physique Théorique des Particules, Département des Sciences de la Terre et de L' Atmosphère, Université du Québec à Montréal, Case Postale 8888, Succ. Centre-Ville, Montréal, Québec, H3C 3P8 (Canada); Pourtolami, Nima, E-mail: n_pour@live.concordia.ca [Department of Physics, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6 (Canada); Toharia, Manuel, E-mail: mtoharia@physics.concordia.ca [Department of Physics, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4B 1R6 (Canada)

2015-03-06

In a model of warped extra-dimensions with all matter fields in the bulk, we propose a scenario which explains all the masses and mixings of the SM fermions. In this scenario, the same flavor symmetric structure is imposed on all the fermions of the Standard Model (SM), including neutrinos. Due to the exponential sensitivity on bulk fermion masses, a small breaking of this symmetry can be greatly enhanced and produce seemingly un-symmetric hierarchical masses and small mixing angles among the charged fermion zero-modes (SM quarks and charged leptons), thus washing out visible effects of the symmetry. If the Dirac neutrinos are sufficiently localized towards the UV boundary, and the Higgs field leaking into the bulk, the neutrino mass hierarchy and flavor structure will still be largely dominated and reflect the fundamental flavor structure, whereas localization of the quark sector would reflect the effects of the flavor symmetry breaking sector. We explore these features in an example based on which a family permutation symmetry is imposed in both quark and lepton sectors.

Intrinsic Rotation and Momentum Transport in Reversed Shear Plasmas with Internal Transport Barriers

Science.gov (United States)

Jhang, Hogun; Kim, S. S.; Diamond, P. H.

2010-11-01

The intrinsic rotation in fusion plasmas is believed to be generated via the residual stress without external momentum input. The physical mechanism responsible for the generation and transport of intrinsic rotation in L- and H-mode tokamak plasmas has been studied extensively. However, it is noted that the physics of intrinsic rotation generation and its relationship to the formation of internal transport barriers (ITBs) in reversed shear (RS) tokamak plasmas have not been explored in detail, which is the main subject in the present work. A global gyrofluid code TRB is used for this study. It is found that the large intrinsic rotation (˜10-30% of the ion sound speed depending on ITB characteristics) is generated near the ITB region and propagates into the core. The intrinsic rotation increases linearly as the temperature gradient at ITB position increases, albeit not indefinitely. Key parameters related to the symmetry breaking, such as turbulent intensity and its gradient, the flux surface averaged parallel wavenumber are evaluated dynamically during the ITB formation. The role of reversed shear and the q-profile curvature is presented in relation to the symmetry breaking mechanism in RS plasmas.

Personality Is Reflected in the Brain's Intrinsic Functional Architecture

Science.gov (United States)

Adelstein, Jonathan S.; Shehzad, Zarrar; Mennes, Maarten; DeYoung, Colin G.; Zuo, Xi-Nian; Kelly, Clare; Margulies, Daniel S.; Bloomfield, Aaron; Gray, Jeremy R.; Castellanos, F. Xavier; Milham, Michael P.

2011-01-01

Personality describes persistent human behavioral responses to broad classes of environmental stimuli. Investigating how personality traits are reflected in the brain's functional architecture is challenging, in part due to the difficulty of designing appropriate task probes. Resting-state functional connectivity (RSFC) can detect intrinsic activation patterns without relying on any specific task. Here we use RSFC to investigate the neural correlates of the five-factor personality domains. Based on seed regions placed within two cognitive and affective ‘hubs’ in the brain—the anterior cingulate and precuneus—each domain of personality predicted RSFC with a unique pattern of brain regions. These patterns corresponded with functional subdivisions responsible for cognitive and affective processing such as motivation, empathy and future-oriented thinking. Neuroticism and Extraversion, the two most widely studied of the five constructs, predicted connectivity between seed regions and the dorsomedial prefrontal cortex and lateral paralimbic regions, respectively. These areas are associated with emotional regulation, self-evaluation and reward, consistent with the trait qualities. Personality traits were mostly associated with functional connections that were inconsistently present across participants. This suggests that although a fundamental, core functional architecture is preserved across individuals, variable connections outside of that core encompass the inter-individual differences in personality that motivate diverse responses. PMID:22140453

Personality is reflected in the brain's intrinsic functional architecture.

Directory of Open Access Journals (Sweden)

Jonathan S Adelstein

Full Text Available Personality describes persistent human behavioral responses to broad classes of environmental stimuli. Investigating how personality traits are reflected in the brain's functional architecture is challenging, in part due to the difficulty of designing appropriate task probes. Resting-state functional connectivity (RSFC can detect intrinsic activation patterns without relying on any specific task. Here we use RSFC to investigate the neural correlates of the five-factor personality domains. Based on seed regions placed within two cognitive and affective 'hubs' in the brain--the anterior cingulate and precuneus--each domain of personality predicted RSFC with a unique pattern of brain regions. These patterns corresponded with functional subdivisions responsible for cognitive and affective processing such as motivation, empathy and future-oriented thinking. Neuroticism and Extraversion, the two most widely studied of the five constructs, predicted connectivity between seed regions and the dorsomedial prefrontal cortex and lateral paralimbic regions, respectively. These areas are associated with emotional regulation, self-evaluation and reward, consistent with the trait qualities. Personality traits were mostly associated with functional connections that were inconsistently present across participants. This suggests that although a fundamental, core functional architecture is preserved across individuals, variable connections outside of that core encompass the inter-individual differences in personality that motivate diverse responses.

Symmetries of Ginsparg-Wilson chiral fermions

International Nuclear Information System (INIS)

Mandula, Jeffrey E.

2009-01-01

The group structure of the variant chiral symmetry discovered by Luescher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of this extended chiral group, and the CP transformation properties of the symmetry generators are found. The group has an infinite-parameter invariant subgroup, and the factor group, whose elements are its cosets, is isomorphic to the continuum chiral symmetry group. Features of the currents associated with these symmetries are discussed, including the fact that some different, noncommuting symmetry generators lead to the same Noether current. These are universal features of lattice chiral fermions based on the Ginsparg-Wilson relation; they occur in the overlap, domain-wall, and perfect-action formulations. In a solvable example, free overlap fermions, these noncanonical elements of lattice chiral symmetry are related to complex energy singularities that violate reflection positivity and impede continuation to Minkowski space.

A qualitative test for intrinsic size effect on ferroelectric phase transitions

OpenAIRE

Wang, Jin; Tagantsev, Alexander K.; Setter, Nava

2010-01-01

The size effect in ferroelectrics is treated as a competition between the geometrical symmetry of the ferroelectric sample and its crystalline symmetry. The manifestation of this competition is shown to be polarization rotation, which is driven by temperature and/or size variations, thus providing a qualitative indication of intrinsic finite size effect on ferroelectrics. The concept is demonstrated in a simple case of PbTiO3 nanowires having their axis parallel to [111]C direction, where the...

Symmetry aspects in emergent quantum mechanics

Science.gov (United States)

Elze, Hans-Thomas

2009-06-01

We discuss an explicit realization of the dissipative dynamics anticipated in the proof of 't Hooft's existence theorem, which states that 'For any quantum system there exists at least one deterministic model that reproduces all its dynamics after prequantization'. - There is an energy-parity symmetry hidden in the Liouville equation, which mimics the Kaplan-Sundrum protective symmetry for the cosmological constant. This symmetry may be broken by the coarse-graining inherent in physics at scales much larger than the Planck length. We correspondingly modify classical ensemble theory by incorporating dissipative fluctuations (information loss) - which are caused by discrete spacetime continually 'measuring' matter. In this way, aspects of quantum mechanics, such as the von Neumann equation, including a Lindblad term, arise dynamically and expectations of observables agree with the Born rule. However, the resulting quantum coherence is accompanied by an intrinsic decoherence and continuous localization mechanism. Our proposal leads towards a theory that is linear and local at the quantum mechanical level, but the relation to the underlying classical degrees of freedom is nonlocal.

Higher-rank discrete symmetries in the IBM I. Octahedral shapes: General Hamiltonian

Energy Technology Data Exchange (ETDEWEB)

Van Isacker, P., E-mail: isacker@ganil.fr [Grand Accélérateur National d' Ions Lourds, CEA/DSM–CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Bouldjedri, A.; Zerguine, S. [Department of Physics, PRIMALAB Laboratory, University of Batna, Avenue Boukhelouf M El Hadi, 05000 Batna (Algeria)

2015-06-15

In the context of the interacting boson model with s, d and g bosons, the conditions for obtaining an intrinsic shape with octahedral symmetry are derived for a general Hamiltonian with up to two-body interactions.

Mutual transformation of light waves by reflection holograms in photorefractive crystals of the 4-bar 3m symmetry

Energy Technology Data Exchange (ETDEWEB)

Naunyka, V. N.; Shepelevich, V. V., E-mail: vasshep@inbox.ru [Mozyr State Pedagogical University (Belarus)

2011-05-15

The mutual transformation of light waves in the case of their simultaneous diffraction from a bulk reflection phase hologram, which was formed in a cubic photorefractive crystal of the 4-bar 3m symmetry class, has been studied. The indicator surfaces of the polarization-optimized values of the relative intensity of the object wave, which make it possible to determine the amplification of this wave for any crystal cut, are constructed. The linear polarization azimuths at which the energy exchange between the light waves reaches a maximum are found numerically for crystals of different cuts.

Gyrofluid Simulations of Intrinsic Rotation Generation in Reversed Shear Plasmas with Internal Transport Barriers

Science.gov (United States)

Jhang, Hogun; Kim, S. S.; Kwon, J. M.; Terzolo, L.; Kim, J. Y.; Diamond, P. H.

2010-11-01

It is accepted that the intrinsic rotation is generated via the residual stress, which is non-diffusive components of the turbulent Reynolds stress, without external momentum input. The physics leading to the onset of intrinsic rotation in L- and H- mode plasmas have been elucidated elsewhere. However, the physics responsible for the generation and transport of the intrinsic rotation and its relationship to the formation of internal transport barriers (ITBs) in reversed shear (RS) plasmas have not been explored in detail, which is the main subject in the present work. The revised version of the global gyrofluid code TRB is used for this study. It is found that the large intrinsic rotation (˜10-30% of the ion sound speed depending on ITB characteristics) is generated near the ITB region and propagates into the core. The intrinsic rotation increases linearly as the temperature gradient at ITB position increases, albeit not indefinitely. Key parameters related to the symmetry breaking, such as turbulent intensity and its gradient, the flux surface averaged parallel wavenumber are evaluated dynamically during the ITB formation. In particular, the role of reversed shear and the q-profile curvature is presented in relation to the symmetry breaking in RS plasmas.

The value of nature: Economic, intrinsic, or both?

Science.gov (United States)

There has been a long standing argument that ecosystems have intrinsic value and therefore there is no need to put a price tag on Mother Nature. The concept of intrinsic value reflects the perspective that nature has value in its own right, independent of human uses. Intrinsic va...

Fluid and flexible minds: Intelligence reflects synchrony in the brain’s intrinsic network architecture

Directory of Open Access Journals (Sweden)

Michael A. Ferguson

2017-06-01

Full Text Available Human intelligence has been conceptualized as a complex system of dissociable cognitive processes, yet studies investigating the neural basis of intelligence have typically emphasized the contributions of discrete brain regions or, more recently, of specific networks of functionally connected regions. Here we take a broader, systems perspective in order to investigate whether intelligence is an emergent property of synchrony within the brain’s intrinsic network architecture. Using a large sample of resting-state fMRI and cognitive data (n = 830, we report that the synchrony of functional interactions within and across distributed brain networks reliably predicts fluid and flexible intellectual functioning. By adopting a whole-brain, systems-level approach, we were able to reliably predict individual differences in human intelligence by characterizing features of the brain’s intrinsic network architecture. These findings hold promise for the eventual development of neural markers to predict changes in intellectual function that are associated with neurodevelopment, normal aging, and brain disease. In our study, we aimed to understand how individual differences in intellectual functioning are reflected in the intrinsic network architecture of the human brain. We applied statistical methods, known as spectral decompositions, in order to identify individual differences in the synchronous patterns of spontaneous brain activity that reliably predict core aspects of human intelligence. The synchrony of brain activity at rest across multiple discrete neural networks demonstrated positive relationships with fluid intelligence. In contrast, global synchrony within the brain’s network architecture reliably, and inversely, predicted mental flexibility, a core facet of intellectual functioning. The multinetwork systems approach described here represents a methodological and conceptual extension of earlier efforts that related differences in

Intrinsic symmetry of the scaling laws and generalized relations for critical indices

International Nuclear Information System (INIS)

Plechko, V.N.

1982-01-01

It is shown that the scating taws for criticat induces can be expressed as a consequence of a simple symmetry principle. Heuristic relations for critical induces of generalizing scaling laws for the case of arbitrary order parameters are presented, which manifestiy have a symmetric form and include the standard scalling laws as a particular case

FT-IR reflection spectra of single crystals: resolving phonons of different symmetry without using polarised radiation

Directory of Open Access Journals (Sweden)

METODIJA NAJDOSKI

2000-07-01

Full Text Available Fourier-transform infrared (FT-IR reflection spectra, asquired at nearnormal incidence, were recorded from single crystals belonging to six crystal systems: CsCr(SO42.12H2O (alum, cubic, K2CuCl2·2H2O (Mitscherlichite, tetragonal, CaCO3 (calcite, hexagonal, KHSO4 (mercallite, orthorhombic, CaSO4·2H2O (gypsum, monoclinic and CuSO4·5H2O (chalcantite, triclinic. The acquired IR reflection spectra were further transformed into absorption spectra, employing the Kramers-Kronig transformation. Except for the cubic alums, the spectra strongly depend on the crystal face from which they were recorded; this is a consequence of anisotropy. Phonons of a given symmetry (E-species, in tetragonal/hexagonal and B-species, in monoclinic crystals may be resolved without using a polariser. The spectrum may be simplified in the case of an orthorhombic crystal, as well. The longitudinal-optical (LO and transversal-optical (TO mode frequencies were calculated in the case of optically isotropic and the simplified spectra of optically uniaxial crystals.

Symmetry analysis of cellular automata

International Nuclear Information System (INIS)

García-Morales, V.

2013-01-01

By means of B-calculus [V. García-Morales, Phys. Lett. A 376 (2012) 2645] a universal map for deterministic cellular automata (CAs) has been derived. The latter is shown here to be invariant upon certain transformations (global complementation, reflection and shift). When constructing CA rules in terms of rules of lower range a new symmetry, “invariance under construction” is uncovered. Modular arithmetic is also reformulated within B-calculus and a new symmetry of certain totalistic CA rules, which calculate the Pascal simplices modulo an integer number p, is then also uncovered.

Physics in the intrinsic coordinate frames with the universal mean field potential: spontaneous parity breaking and exotic shapes in high-spin states

International Nuclear Information System (INIS)

Dudek, J.

1989-01-01

The concept of a ''universal'' average field as a basis of intrinsic-frame nuclear physics is stressed. The symmetries of such an average field are discussed. As an important application, an overwiew is given of the recent progress in understanding the octupole-type (intrinsic-parity breaking) degrees of freedom in nuclei. Their importance and the new consequences resulting from the related symmetries and spontaneous symmetry breaking phenomena are emphasized: the presence of static and/or dynamic isovector deformations and their implications, the possible low-energy E1 cooling in moderately hot nuclei at high spins, possible new forms of rotational dumping effects in rotating nuclei etc

Gauging the graded conformal group with unitary internal symmetries

International Nuclear Information System (INIS)

Ferrara, S.; Townsend, P.K.; Kaku, M.; Nieuwenhuizen Van, P.

1977-06-01

Gauge theories for extended SU(N) conformal supergravity are constructed which are invariant under local scale, chiral, proper conformal, supersymmetry and internal SU(N) transformations. The relation between intrinsic parity and symmetry properties of their generators of the internal vector mesons is established. These theories contain no cosmological constants, but technical problems inherent to higher derivative actions are pointed out

Symmetry and binding in visuo-spatial working memory.

Science.gov (United States)

Rossi-Arnaud, C; Pieroni, L; Baddeley, A

2006-04-28

Three experiments study the impact of symmetry on a sequential block tapping immediate memory task in human subjects. Experiment 1 shows an advantage from vertical symmetry over non-symmetrical sequences, while finding no effect of horizontal or diagonal symmetry. Experiment 2 tests the possible role of verbal labeling by means of a secondary task that prevents this by articulatory suppression. No evidence of verbalization was observed. A third study examines the effects of a concurrent executive load, finding an overall impairment, that did not differ between symmetrical and asymmetric patterns, suggesting that the effect of symmetry reflects automatic rather than executive processes. Implications for the episodic buffer component of working memory are discussed.

Quregisters, Symmetry Groups and Clifford Algebras

International Nuclear Information System (INIS)

Cervantes, D; Morales-Luna, G

2016-01-01

Natural one-to-one and two-to-one homomorphisms from SO(3) into SU(2) are built conventionally, and the collection of qubits, is identified with a subgroup of SU(2). This construction is suitable to be extended to corresponding tensor powers. The notions of qubits, quregisters and qugates are translated into the language of symmetry groups. The corresponding elements to entangled states in the tensor product of Hilbert spaces reflect entanglement properties as well, and in this way a notion of entanglement is realised in the tensor product of symmetry groups. (paper)

Antiunitary symmetry operators in quantum mechanics

International Nuclear Information System (INIS)

Carinena, J.F.; Santander, M.

1981-01-01

A criterion to decide that some symmetries of a quantum system must be realized as antiunitary operators is given. It is based on some mathematical theorems about the second cohomology group of the symmetry group when expressed in terms of those of a normal subgroup and the corresponding factor group. It is also shown that this criterion implies that the only possibility for the unitary subgroup in the Galilean case is that generated by the space reflection and the connected component containing the identity; otherwise only massless systems would arise. (author)

Core-Shell Particles as Building Blocks for Systems with High Duality Symmetry

Science.gov (United States)

Rahimzadegan, Aso; Rockstuhl, Carsten; Fernandez-Corbaton, Ivan

2018-05-01

Material electromagnetic duality symmetry requires a system to have equal electric and magnetic responses. Intrinsically dual materials that meet the duality conditions at the level of the constitutive relations do not exist in many frequency bands. Nevertheless, discrete objects like metallic helices and homogeneous dielectric spheres can be engineered to approximate the dual behavior. We exploit the extra degrees of freedom of a core-shell dielectric sphere in a particle optimization procedure. The duality symmetry of the resulting particle is more than 1 order of magnitude better than previously reported nonmagnetic objects. We use T -matrix-based multiscattering techniques to show that the improvement is transferred onto the duality symmetry of composite objects when the core-shell particle is used as a building block instead of homogeneous spheres. These results are relevant for the fashioning of systems with high duality symmetry, which are required for some technologically important effects.

Intrinsic and Extrinsic Motivations: Classic Definitions and New Directions.

Science.gov (United States)

Ryan; Deci

2000-01-01

Intrinsic and extrinsic types of motivation have been widely studied, and the distinction between them has shed important light on both developmental and educational practices. In this review we revisit the classic definitions of intrinsic and extrinsic motivation in light of contemporary research and theory. Intrinsic motivation remains an important construct, reflecting the natural human propensity to learn and assimilate. However, extrinsic motivation is argued to vary considerably in its relative autonomy and thus can either reflect external control or true self-regulation. The relations of both classes of motives to basic human needs for autonomy, competence and relatedness are discussed. Copyright 2000 Academic Press.

Strong-field ionization of linear molecules by a bicircular laser field: Symmetry considerations

Science.gov (United States)

Gazibegović-Busuladžić, A.; Busuladžić, M.; Hasović, E.; Becker, W.; Milošević, D. B.

2018-04-01

Using the improved molecular strong-field approximation, we investigate (high-order) above-threshold ionization [(H)ATI] of various linear polyatomic molecules by a two-color laser field of frequencies r ω and s ω (with integer numbers r and s ) having coplanar counter-rotating circularly polarized components (a so-called bicircular field). Reflection and rotational symmetries for molecules aligned in the laser-field polarization plane, analyzed for diatomic homonuclear molecules in Phys. Rev. A 95, 033411 (2017), 10.1103/PhysRevA.95.033411, are now considered for diatomic heteronuclear molecules and symmetric and asymmetric linear triatomic molecules. There are additional rotational symmetries for (H)ATI spectra of symmetric linear molecules compared to (H)ATI spectra of the asymmetric ones. It is shown that these symmetries manifest themselves differently for r +s odd and r +s even. For example, HATI spectra for symmetric molecules with r +s even obey inversion symmetry. For ATI spectra of linear molecules, reflection symmetry appears only for certain molecular orientation angles ±90∘-j r 180∘/(r +s ) (j integer). For symmetric linear molecules, reflection symmetry appears also for the angles -j r 180∘/(r +s ) . For perpendicular orientation of molecules with respect to the laser-field polarization plane, the HATI spectra are very similar to those of the atomic targets, i.e., both spectra are characterized by the same type of the (r +s )-fold symmetry.

The Plasma Sheet as Natural Symmetry Plane for Dipolarization Fronts in the Earth's Magnetotail

Science.gov (United States)

Frühauff, D.; Glassmeier, K.-H.

2017-11-01

In this work, observations of multispacecraft mission Time History of Events and Macroscale Interactions during Substorms are used for statistical investigation of dipolarization fronts in the near-Earth plasma sheet of the magnetotail. Using very stringent criteria, 460 events are detected in almost 10 years of mission data. Minimum variance analysis is used to determine the normal directions of the phase fronts, providing evidence for the existence of a natural symmetry of these phenomena, given by the neutral sheet of the magnetotail. This finding enables the definition of a local coordinate system based on the Tsyganenko model, reflecting the intrinsic orientation of the neutral sheet and, therefore, the dipolarization fronts. In this way, the comparison of events with very different background conditions is improved. Through this study, the statistical results of Liu, Angelopoulos, Runov, et al. (2013) are both confirmed and extended. In a case study, the knowledge of this plane of symmetry helps to explain the concave curvature of dipolarization fronts in the XZ plane through phase propagation speeds of magnetoacoustic waves. A second case study is presented to determine the central current system of a passing dipolarization front through a constellation of three spacecraft. With this information, a statistical analysis of spacecraft observations above and below the neutral sheet is used to provide further evidence for the neutral sheet as the symmetry plane and the central current system. Furthermore, it is shown that the signatures of dipolarization fronts are under certain conditions closely related to that of flux ropes, indicating a possible relationship between these two transient phenomena.

Timelike symmetry of the quantum transition and Einstein-Podolsky-Rosen paradox

International Nuclear Information System (INIS)

Costa de Beauregard, Olivier

1976-01-01

The non-locality in the paradox is very close to that of Feynman's electron-positron system: the sum of two timelike vectors with 4th components of opposite signs may be spacelike. The intrinsic time symmetry of the quantum transition consists in the presence of both the delayed and the advanced wave inside the ''collapsed'' wave [fr

Physics of Intrinsic Rotation in Flux-Driven ITG Turbulence

International Nuclear Information System (INIS)

Ku, S.; Abiteboul, J.; Dimond, P.H.; Dif-Pradalier, G.; Kwon, J.M.; Sarazin, Y.; Hahm, T.S.; Garbet, X.; Chang, C.S.; Latu, G.; Yoon, E.S.; Ghendrih, Ph.; Yi, S.; Strugarek, A.; Solomon, W.; Grandgirard, V.

2012-01-01

Global, heat flux-driven ITG gyrokinetic simulations which manifest the formation of macroscopic, mean toroidal flow profiles with peak thermal Mach number 0.05, are reported. Both a particle-in-cell (XGC1p) and a semi-Lagrangian (GYSELA) approach are utilized without a priori assumptions of scale-separation between turbulence and mean fields. Flux-driven ITG simulations with different edge flow boundary conditions show in both approaches the development of net unidirectional intrinsic rotation in the co-current direction. Intrinsic torque is shown to scale approximately linearly with the inverse scale length of the ion temperature gradient. External momentum input is shown to effectively cancel the intrinsic rotation profile, thus confirming the existence of a local residual stress and intrinsic torque. Fluctuation intensity, intrinsic torque and mean flow are demonstrated to develop inwards from the boundary. The measured correlations between residual stress and two fluctuation spectrum symmetry breakers, namely E x B shear and intensity gradient, are similar. Avalanches of (positive) heat flux, which propagate either outwards or inwards, are correlated with avalanches of (negative) parallel momentum flux, so that outward transport of heat and inward transport of parallel momentum are correlated and mediated by avalanches. The probability distribution functions of the outward heat flux and the inward momentum flux show strong structural similarity

Nonlocal thermoelectric symmetry relations in ferromagnet-superconductor proximity structures

Energy Technology Data Exchange (ETDEWEB)

Machon, Peter; Belzig, Wolfgang [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Eschrig, Matthias [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Department of Physics, Royal Holloway, University of London, Egham Hill, EGHAM, TW20 0EX (United Kingdom)

2012-07-01

The symmetries of thermal and electric transport coefficients in quantum coherent structures are related to fundamental thermodynamic principles by the Onsager reciprocity. We generalize Onsager's symmetry relation to nonlocal thermoelectric currents in a three terminal ferromagnet-superconductor heterostructure including spin-dependent crossed Andreev reflection and direct electron transfer processes. We proof this general symmetry by applying spin-dependent boundary conditions for quasi-classical Green's functions in both the clean and the dirty limit. We predict an anomalously large local thermopower and a nonlocal Seebeck effect, which can be explained by the spin-dependent spectral properties.

Multivector field formulation of Hamiltonian field theories: equations and symmetries

Energy Technology Data Exchange (ETDEWEB)

Echeverria-Enriquez, A.; Munoz-Lecanda, M.C.; Roman-Roy, N. [Departamento de Matematica Aplicada y Telematica, Edificio C-3, Campus Norte UPC, Barcelona (Spain)

1999-12-03

We state the intrinsic form of the Hamiltonian equations of first-order classical field theories in three equivalent geometrical ways: using multivector fields, jet fields and connections. Thus, these equations are given in a form similar to that in which the Hamiltonian equations of mechanics are usually given. Then, using multivector fields, we study several aspects of these equations, such as the existence and non-uniqueness of solutions, and the integrability problem. In particular, these problems are analysed for the case of Hamiltonian systems defined in a submanifold of the multimomentum bundle. Furthermore, the existence of first integrals of these Hamiltonian equations is considered, and the relation between Cartan-Noether symmetries and general symmetries of the system is discussed. Noether's theorem is also stated in this context, both the 'classical' version and its generalization to include higher-order Cartan-Noether symmetries. Finally, the equivalence between the Lagrangian and Hamiltonian formalisms is also discussed. (author)

Where to Go: Breaking the Symmetry in Cell Motility

Science.gov (United States)

2016-01-01

Cell migration in the “correct” direction is pivotal for many biological processes. Although most work is devoted to its molecular mechanisms, the cell’s preference for one direction over others, thus overcoming intrinsic random motility, epitomizes a profound principle that underlies all complex systems: the choice of one axis, in structure or motion, from a uniform or symmetric set of options. Explaining directional motility by an external chemo-attractant gradient does not solve but only shifts the problem of causation: whence the gradient? A new study in PLOS Biology shows cell migration in a self-generated gradient, offering an opportunity to take a broader look at the old dualism of extrinsic instruction versus intrinsic symmetry-breaking in cell biology. PMID:27196433

Symmetry breaking in small rotating clouds of trapped ultracold Bose atoms

International Nuclear Information System (INIS)

Dagnino, D.; Barberan, N.; Riera, A.; Osterloh, K.; Lewenstein, M.

2007-01-01

We study the signatures of rotational and phase symmetry breaking in small rotating clouds of trapped ultracold Bose atoms by looking at rigorously defined condensate wave function. Rotational symmetry breaking occurs in narrow frequency windows, where energy degeneracy between the lowest energy states of different total angular momentum takes place. This leads to a complex condensate wave function that exhibits vortices clearly seen as holes in the density, as well as characteristic local phase patterns, reflecting the appearance of vorticities. Phase symmetry (or gauge symmetry) breaking, on the other hand, is clearly manifested in the interference of two independent rotating clouds

Trapped Electron Mode Turbulence Driven Intrinsic Rotation in Tokamak Plasmas

International Nuclear Information System (INIS)

Wang, W.X.; Hahm, T.S.; Ethier, S.; Zakharov, L.E.

2011-01-01

Recent progress from global gyrokinetic simulations in understanding the origin of intrinsic rotation in toroidal plasmas is reported with emphasis on electron thermal transport dominated regimes. The turbulence driven intrinsic torque associated with nonlinear residual stress generation by the fluctuation intensity and the intensity gradient in the presence of zonal flow shear induced asymmetry in the parallel wavenumber spectrum is shown to scale close to linearly with plasma gradients and the inverse of the plasma current. These results qualitatively reproduce empirical scalings of intrinsic rotation observed in various experiments. The origin of current scaling is found to be due to enhanced kll symmetry breaking induced by the increased radial variation of the safety factor as the current decreases. The physics origin for the linear dependence of intrinsic torque on pressure gradient is that both turbulence intensity and the zonal flow shear, which are two key ingredients for driving residual stress, increase with the strength of turbulence drive, which is R0/LTe and R0/Lne for the trapped electron mode.

Chiral symmetry and chiral-symmetry breaking

International Nuclear Information System (INIS)

Peskin, M.E.

1982-12-01

These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed

The Novel Quantitative Technique for Assessment of Gait Symmetry Using Advanced Statistical Learning Algorithm

Directory of Open Access Journals (Sweden)

Jianning Wu

2015-01-01

Full Text Available The accurate identification of gait asymmetry is very beneficial to the assessment of at-risk gait in the clinical applications. This paper investigated the application of classification method based on statistical learning algorithm to quantify gait symmetry based on the assumption that the degree of intrinsic change in dynamical system of gait is associated with the different statistical distributions between gait variables from left-right side of lower limbs; that is, the discrimination of small difference of similarity between lower limbs is considered the reorganization of their different probability distribution. The kinetic gait data of 60 participants were recorded using a strain gauge force platform during normal walking. The classification method is designed based on advanced statistical learning algorithm such as support vector machine algorithm for binary classification and is adopted to quantitatively evaluate gait symmetry. The experiment results showed that the proposed method could capture more intrinsic dynamic information hidden in gait variables and recognize the right-left gait patterns with superior generalization performance. Moreover, our proposed techniques could identify the small significant difference between lower limbs when compared to the traditional symmetry index method for gait. The proposed algorithm would become an effective tool for early identification of the elderly gait asymmetry in the clinical diagnosis.

The novel quantitative technique for assessment of gait symmetry using advanced statistical learning algorithm.

Science.gov (United States)

Wu, Jianning; Wu, Bin

2015-01-01

The accurate identification of gait asymmetry is very beneficial to the assessment of at-risk gait in the clinical applications. This paper investigated the application of classification method based on statistical learning algorithm to quantify gait symmetry based on the assumption that the degree of intrinsic change in dynamical system of gait is associated with the different statistical distributions between gait variables from left-right side of lower limbs; that is, the discrimination of small difference of similarity between lower limbs is considered the reorganization of their different probability distribution. The kinetic gait data of 60 participants were recorded using a strain gauge force platform during normal walking. The classification method is designed based on advanced statistical learning algorithm such as support vector machine algorithm for binary classification and is adopted to quantitatively evaluate gait symmetry. The experiment results showed that the proposed method could capture more intrinsic dynamic information hidden in gait variables and recognize the right-left gait patterns with superior generalization performance. Moreover, our proposed techniques could identify the small significant difference between lower limbs when compared to the traditional symmetry index method for gait. The proposed algorithm would become an effective tool for early identification of the elderly gait asymmetry in the clinical diagnosis.

Symmetry and symmetry breaking

International Nuclear Information System (INIS)

Balian, R.; Lambert, D.; Brack, A.; Lachieze-Rey, M.; Emery, E.; Cohen-Tannoudji, G.; Sacquin, Y.

1999-01-01

The symmetry concept is a powerful tool for our understanding of the world. It allows a reduction of the volume of information needed to apprehend a subject thoroughly. Moreover this concept does not belong to a particular field, it is involved in the exact sciences but also in artistic matters. Living beings are characterized by a particular asymmetry: the chiral asymmetry. Although this asymmetry is visible in whole organisms, it seems it comes from some molecules that life always produce in one chirality. The weak interaction presents also the chiral asymmetry. The mass of particles comes from the breaking of a fundamental symmetry and the void could be defined as the medium showing as many symmetries as possible. The texts put together in this book show to a great extent how symmetry goes far beyond purely geometrical considerations. Different aspects of symmetry ideas are considered in the following fields: the states of matter, mathematics, biology, the laws of Nature, quantum physics, the universe, and the art of music. (A.C.)

Unexpected magnetism in low dimensional systems: the role of symmetry

International Nuclear Information System (INIS)

Munoz, MC; Chico, L; Lopez-Sancho, MP; Beltran, JI; Gallego, S; Cerda, J

2006-01-01

The symmetry underlying the geometric structure of materials determines most of their physical properties. In low dimensional systems the role of symmetry is enhanced and can give rise to new phenomena. Here, we report on unexpected magnetism in carbon nanotubes and O-rich surfaces of ionic oxides, to show how its existence is closely related to the symmetry conditions. First, based on tight-binding models, we demonstrate that chiral carbon nanotubes present spin splitting at the Fermi level in the absence of a magneticfield, whereas achiral tubes preserve spin degeneracy. These remarkably different behaviors of chiral and non-chiral nanotubes are due to the intrinsic symmetry dependence of the spin-orbit interaction. Second, the occurrence of spin-polarization at ZrO 2 , Al 2 O 3 and MgO surfaces is proved by means of abinitio calculations within the density functional theory. Large spin moments develop at O-ended polar terminations, transforming the non-magnetic insulator into a half-metal. The magnetic moments mainly reside in the surface oxygen atoms, and their origin is related to the existence of 2p holes of well-defined spin polarization at the valence band of the ionic oxide. The direct relation between magnetization and local loss of donor charge shows that at the origin of these phenomena is the reduced surface symmetry

Effects of the symmetry axis orientation of a TI overburden on seismic images

Science.gov (United States)

Chang, Chih-Hsiung; Chang, Young-Fo; Tseng, Cheng-Wei

2017-07-01

In active tectonic regions, the primary formations are often tilted and subjected to the processes of folding and/or faulting. Dipping formations may be categorised as tilted transverse isotropy (TTI). While carrying out hydrocarbon exploration in areas of orogenic structures, mispositioning and defocusing effects in apparent reflections are often caused by the tilted transverse isotropy of the overburden. In this study, scaled physical modelling was carried out to demonstrate the behaviours of seismic wave propagation and imaging problems incurred by transverse isotropic (TI) overburdens that possess different orientations of the symmetry axis. To facilitate our objectives, zero-offset reflections were acquired from four stratum-fault models to image the same structures that were overlain by a TI (phenolite) slab. The symmetry axis of the TI slab was vertical, tilted or horizontal. In response to the symmetry axis orientations, spatial shifts and asymmetrical diffraction patterns in apparent reflections were observed in the acquired profiles. Given the different orientations of the symmetry axis, numerical manipulations showed that the imaged events could be well described by theoretical ray paths computed by the trial-and-error ray method and Fermat's principle (TERF) method. In addition, outputs of image restoration show that the imaging problems, i.e. spatial shift in the apparent reflections, can be properly handled by the ray-based anisotropic 2D Kirchhoff time migration (RAKTM) method.

Implications of physical symmetries in adaptive image classifiers

DEFF Research Database (Denmark)

Sams, Thomas; Hansen, Jonas Lundbek

2000-01-01

It is demonstrated that rotational invariance and reflection symmetry of image classifiers lead to a reduction in the number of free parameters in the classifier. When used in adaptive detectors, e.g. neural networks, this may be used to decrease the number of training samples necessary to learn...... a given classification task, or to improve generalization of the neural network. Notably, the symmetrization of the detector does not compromise the ability to distinguish objects that break the symmetry. (C) 2000 Elsevier Science Ltd. All rights reserved....

Symmetry of priapulids (Priapulida). 2. Symmetry of larvae.

Science.gov (United States)

Adrianov, A V; Malakhov, V V

2001-02-01

Larvae of priapulids are characterized by radial symmetry evident from both external and internal characters of the introvert and lorica. The bilaterality appears as a result of a combination of several radial symmetries: pentaradial symmetry of the teeth, octaradial symmetry of the primary scalids, 25-radial symmetry of scalids, biradial symmetry of the neck, and biradial and decaradial symmetry of the trunk. Internal radiality is exhibited by musculature and the circumpharyngeal nerve ring. Internal bilaterality is evident from the position of the ventral nerve cord and excretory elements. Externally, the bilaterality is determined by the position of the anal tubulus and two shortened midventral rows of scalids bordering the ventral nerve cord. The lorical elements define the biradial symmetry that is missing in adult priapulids. The radial symmetry of larvae is a secondary appearance considered an evolutionary adaptation to a lifestyle within the three-dimensional environment of the benthic sediment. Copyright 2001 Wiley-Liss, Inc.

Quantum Space-Time Deformed Symmetries Versus Broken Symmetries

CERN Document Server

Amelino-Camelia, G

2002-01-01

Several recent studies have concerned the faith of classical symmetries in quantum space-time. In particular, it appears likely that quantum (discretized, noncommutative,...) versions of Minkowski space-time would not enjoy the classical Lorentz symmetries. I compare two interesting cases: the case in which the classical symmetries are "broken", i.e. at the quantum level some classical symmetries are lost, and the case in which the classical symmetries are "deformed", i.e. the quantum space-time has as many symmetries as its classical counterpart but the nature of these symmetries is affected by the space-time quantization procedure. While some general features, such as the emergence of deformed dispersion relations, characterize both the symmetry-breaking case and the symmetry-deformation case, the two scenarios are also characterized by sharp differences, even concerning the nature of the new effects predicted. I illustrate this point within an illustrative calculation concerning the role of space-time symm...

Clustering and Symmetry Energy in a Low Density Nuclear Gas

International Nuclear Information System (INIS)

Kowalski, S.; Natowitz, J.B.; Shlomo, S.; Wada, R.; Hagel, K.; Wang, J.; Materna, T.; Chen, Z.; Ma, Y.G.; Qin, L.; Botvina, A.S.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Rizzi, V.; Viesti, G.; Cinausero, M.; Prete, G.; Keutgen, T.; El Masri, Y.; Majka, Z.; Ono, A.

2007-01-01

Temperature and density dependent symmetry energy coefficients have been derived from isoscaling analyses of the yields of nuclei with A= 64 Zn projectiles with 92 Mo and 197 Au target nuclei. The symmetry energies at low density are larger than those obtained in mean field calculations, reflecting the clustering of low density nuclear matter. They are in quite good agreement with results of a recently proposed Virial Equation of State calculation

Realization of tunable spin-dependent splitting in intrinsic photonic spin Hall effect

Energy Technology Data Exchange (ETDEWEB)

Ling, Xiaohui [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China); Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421002 (China); Yi, Xunong [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Zhou, Xinxing; Liu, Yachao; Shu, Weixing; Wen, Shuangchun [Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China); Luo, Hailu, E-mail: hailuluo@hnu.edu.cn [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Laboratory for spin photonics, College of Physics and Microelectronic Science, Hunan University, Changsha 410082 (China)

2014-10-13

We report the realization of tunable spin-dependent splitting in intrinsic photonic spin Hall effect. By breaking the rotational symmetry of a cylindrical vector beam, the intrinsic vortex phases that the two spin components of the vector beam carries, which is similar to the geometric Pancharatnam-Berry phase, are no longer continuous in the azimuthal direction, and leads to observation of spin accumulation at the opposite edge of the beam. Due to the inherent nature of the phase and independency of light-matter interaction, the observed photonic spin Hall effect is intrinsic. Modulating the topological charge of the vector beam, the spin-dependent splitting can be enhanced and the direction of spin accumulation is switchable. Our findings may provide a possible route for generation and manipulation of spin-polarized photons, and enables spin-based photonics applications.

Gompertz' survivorship law as an intrinsic principle of aging

NARCIS (Netherlands)

Sas, Arthur A.; Snieder, Harold; Korf, Jakob

We defend the hypothesis that life-spanning population survivorship curves, as described by Gompertz' law and composed from cross-sectional data (here mortality), reflect an intrinsic aging principle active in each subject of that population. In other words Gompertz' law reflects aging of a

A series of intrinsically chiral gold nanocage structures.

Science.gov (United States)

Liu, X J; Hamilton, I P

2017-07-27

We present a series of intrinsically chiral gold nanocage structures, Au 9n+6 , which are stable for n ≥ 2. These structures consist of an Au 9n tube which is capped with Au 3 units at each end. Removing the Au 3 caps, we obtain a series of intrinsically chiral gold nanotube structures, Au 9n , which are stable for n ≥ 4. The intrinsic chirality of these structures results from the helicity of the gold strands which form the tube and not because an individual Au atom is a chiral center. The symmetry of these structures is C 3 and substructures of gold hexagons with a gold atom in the middle are particularly prominent. We focus on the properties of Au 42 (C 3 ) and Au 105 (C 3 ) which are the two smallest gold nanocage structures to be completely tiled by these Au 7 "golden-eye" substructures. Our main focus is on Au 42 (C 3 ) since gold clusters in the 40-50 atom regime are currently being investigated in gas phase experiments. We show that the intrinsically chiral Au 42 cage structure is energetically comparable with previously reported achiral cage and compact Au 42 structures. Cage structures are of particular interest because species can be encapsulated (and stabilized) inside the cage and we provide strong evidence that Au 6 @Au 42 (C 3 ) is the global minimum Au 48 structure. The intrinsically chiral gold nanocage structures, which exhibit a range of size-related properties, have potential applications in chiral catalysis and as components in nanostructured devices.

Beyond the evoked/intrinsic neural process dichotomy

Directory of Open Access Journals (Sweden)

Taylor Bolt

2018-03-01

Full Text Available Contemporary functional neuroimaging research has increasingly focused on characterization of intrinsic or “spontaneous” brain activity. Analysis of intrinsic activity is often contrasted with analysis of task-evoked activity that has traditionally been the focus of cognitive neuroscience. But does this evoked/intrinsic dichotomy adequately characterize human brain function? Based on empirical data demonstrating a close functional interdependence between intrinsic and task-evoked activity, we argue that the dichotomy between intrinsic and task-evoked activity as unobserved contributions to brain activity is artificial. We present an alternative picture of brain function in which the brain’s spatiotemporal dynamics do not consist of separable intrinsic and task-evoked components, but reflect the enaction of a system of mutual constraints to move the brain into and out of task-appropriate functional configurations. According to this alternative picture, cognitive neuroscientists are tasked with describing both the temporal trajectory of brain activity patterns across time, and the modulation of this trajectory by task states, without separating this process into intrinsic and task-evoked components. We argue that this alternative picture of brain function is best captured in a novel explanatory framework called enabling constraint. Overall, these insights call for a reconceptualization of functional brain activity, and should drive future methodological and empirical efforts.

A hierarchy of intrinsic timescales across primate cortex.

Science.gov (United States)

Murray, John D; Bernacchia, Alberto; Freedman, David J; Romo, Ranulfo; Wallis, Jonathan D; Cai, Xinying; Padoa-Schioppa, Camillo; Pasternak, Tatiana; Seo, Hyojung; Lee, Daeyeol; Wang, Xiao-Jing

2014-12-01

Specialization and hierarchy are organizing principles for primate cortex, yet there is little direct evidence for how cortical areas are specialized in the temporal domain. We measured timescales of intrinsic fluctuations in spiking activity across areas and found a hierarchical ordering, with sensory and prefrontal areas exhibiting shorter and longer timescales, respectively. On the basis of our findings, we suggest that intrinsic timescales reflect areal specialization for task-relevant computations over multiple temporal ranges.

Reflections on Conformal Spectra

CERN Multimedia

CERN. Geneva

2015-01-01

We use modular invariance and crossing symmetry of conformal field theory to reveal approximate reflection symmetries in the spectral decompositions of the partition function in two dimensions in the limit of large central charge and of the four-point function in any dimension in the limit of large scaling dimensions Δ0 of external operators. We use these symmetries to motivate universal upper bounds on the spectrum and the operator product expansion coefficients, which we then derive by independent techniques. Some of the bounds for four-point functions are valid for finite Δ0 as well as for large Δ0. We discuss a similar symmetry in a large spacetime dimension limit. Finally, we comment on the analogue of the Cardy formula and sparse light spectrum condition for the four-point function. (based on 1510.08772 with Kim & Ooguri). This seminar will be given via videolink

Five-fold local symmetry in metallic liquids and glasses

International Nuclear Information System (INIS)

Li M Z; Li F X; Zhang H P; Peng H L; Hu Y C; Wang W H

2017-01-01

The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry. (paper)

On intrinsic and extrinsic origin of plasmon peaks

International Nuclear Information System (INIS)

Takayama, Shoichi; Kawai, Jun

2008-01-01

The origin of the plasmon loss peaks in X-ray photoelectron spectra are discussed based on the (1) intrinsic, (2) extrinsic, (3) quantum interference between (1) and (2), and (4) mixture of (1) and (2). It was believed that the major part of plasmon was due to the extrinsic, the present analysis concludes the major part is intrinsic, depending the excitation energy. This analysis is based on the electron reflection spectra, but valid for X-ray photoelectron spectra. (author)

Leadership, power and symmetry

DEFF Research Database (Denmark)

Spaten, Ole Michael

2016-01-01

Research publications concerning managers who coach their own employees are barely visible despite its wide- spread use in enterprises (McCarthy & Milner, 2013; Gregory & Levy, 2011; Crabb, 2011). This article focuses on leadership, power and moments of symmetry in the coaching relationship...... regarding managers coaching their employees and it is asked; what contributes to coaching of high quality when one reflects on the power aspect as being immanent? Fourteen middle managers coached five of their employees, and all members of each party wrote down cues and experiences immediately after each...

Fermion unification model based on the intrinsic SU(8 symmetry of a generalized Dirac equation

Directory of Open Access Journals (Sweden)

Eckart eMarsch

2015-10-01

Full Text Available A natural generalization of the original Dirac spinor into a multi-component spinor is achieved, which corresponds to the single lepton and the three quarks of the first family of the standard model of elementary particle physics. Different fermions result from similarity transformations of the Dirac equation, but apparently there can be no more fermions according to the maximal multiplicity revealed in this study. Rotations in the fermion state space are achieved by the unitary generators of the U(1 and the SU(3 groups, corresponding to quantum electrodynamics (QED based on electric charge and chromodynamics (QCD based on colour charge. In addition to hypercharge the dual degree of freedom of hyperspin emerges, which occurs due to the duplicity implied by the two related (Weyl and Dirac representations of the Dirac equation. This yields the SU(2 symmetry of the weak interaction, which can be married to U(1 to generate the unified electroweak interaction as in the standard model. Therefore, the symmetry group encompassing all the three groups mentioned above is SU(8, which can accommodate and unify the observed eight basic stable fermions.

Creation and development of the universe (symmetry approach)

International Nuclear Information System (INIS)

Zheludev, I.S.

1993-09-01

The model according to which space subreality and time subreality are created during Big Bang is introduced. The first one is centrosymmetrical, the second anticentrosymmetrical. One to another they are transformed by mutual ''replacement'' space and time. Such subrealities are not antisubrealities and their elementary particles (appeared through Big Bang) are not able to annihilate completely because of symmetry conditions. This leads to the appearance of condensed matter. The model of two subrealities gives the possibility to explain without ''parity violation'' any physical phenomena. Four macroscopic rules of symmetry [scale, corkscrew, gyroscope and right (left) hand] reflect four fundamental interactions of our reality. (author). 10 refs, 16 figs

Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions

OpenAIRE

Wang, Qi; Xu, Yuanfeng; Lou, Rui; Liu, Zhonghao; Li, Man; Huang, Yaobo; Shen, Dawei; Weng, Hongming; Wang, Shancai; Lei, Hechang

2017-01-01

The origin of anomalous Hall effect (AHE) in magnetic materials is one of the most intriguing aspect in condensed matter physics and has been controversial for a long time. Recent studies indicate that the intrinsic AHE is closely related to the Berry curvature of occupied electronic states. In a magnetic Weyl semimetal with broken time-reversal symmetry, there are significant contributions on Berry curvature around Weyl nodes, which would lead to a large intrinsic AHE. Here, we report the la...

Symmetry witnesses

Science.gov (United States)

Aniello, Paolo; Chruściński, Dariusz

2017-07-01

A symmetry witness is a suitable subset of the space of selfadjoint trace class operators that allows one to determine whether a linear map is a symmetry transformation, in the sense of Wigner. More precisely, such a set is invariant with respect to an injective densely defined linear operator in the Banach space of selfadjoint trace class operators (if and) only if this operator is a symmetry transformation. According to a linear version of Wigner’s theorem, the set of pure states—the rank-one projections—is a symmetry witness. We show that an analogous result holds for the set of projections with a fixed rank (with some mild constraint on this rank, in the finite-dimensional case). It turns out that this result provides a complete classification of the sets of projections with a fixed rank that are symmetry witnesses. These particular symmetry witnesses are projectable; i.e. reasoning in terms of quantum states, the sets of ‘uniform’ density operators of corresponding fixed rank are symmetry witnesses too.

Symmetry and symmetry breaking in quantum mechanics

International Nuclear Information System (INIS)

Chomaz, Philippe

1998-01-01

In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation

Electron-phonon interactions and intrinsic nonadiabatic state of superconductors

International Nuclear Information System (INIS)

Banacky, Pavol

2007-01-01

Study of band structure of YBa 2 Cu 3 O 7 has shown that electron coupling to A g , B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > E F . Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2 Cu 3 O 6

Electron phonon interactions and intrinsic nonadiabatic state of superconductors

Science.gov (United States)

Baňacký, Pavol

2007-09-01

Study of band structure of YBa 2Cu 3O 7 has shown that electron coupling to A g, B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > EF. Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2Cu 3O 6.

Symmetry-Adapted Ro-vibrational Basis Functions for Variational Nuclear Motion Calculations: TROVE Approach.

Science.gov (United States)

Yurchenko, Sergei N; Yachmenev, Andrey; Ovsyannikov, Roman I

2017-09-12

We present a general, numerically motivated approach to the construction of symmetry-adapted basis functions for solving ro-vibrational Schrödinger equations. The approach is based on the property of the Hamiltonian operator to commute with the complete set of symmetry operators and, hence, to reflect the symmetry of the system. The symmetry-adapted ro-vibrational basis set is constructed numerically by solving a set of reduced vibrational eigenvalue problems. In order to assign the irreducible representations associated with these eigenfunctions, their symmetry properties are probed on a grid of molecular geometries with the corresponding symmetry operations. The transformation matrices are reconstructed by solving overdetermined systems of linear equations related to the transformation properties of the corresponding wave functions on the grid. Our method is implemented in the variational approach TROVE and has been successfully applied to many problems covering the most important molecular symmetry groups. Several examples are used to illustrate the procedure, which can be easily applied to different types of coordinates, basis sets, and molecular systems.

Electric transport of a single-crystal iron chalcogenide FeSe superconductor: Evidence of symmetry-breakdown nematicity and additional ultrafast Dirac cone-like carriers

Science.gov (United States)

Huynh, K. K.; Tanabe, Y.; Urata, T.; Oguro, H.; Heguri, S.; Watanabe, K.; Tanigaki, K.

2014-10-01

An SDW antiferromagnetic (SDW-AF) low-temperature phase transition is generally observed and the AF spin fluctuations are considered to play an important role for the superconductivity pairing mechanism in FeAs superconductors. However, a similar magnetic phase transition is not observed in FeSe superconductors, which has caused considerable discussion. We report on the intrinsic electronic states of FeSe as elucidated by electric transport measurements under magnetic fields using a high quality single crystal. A mobility spectrum analysis, an ab initio method that does not make assumptions on the transport parameters in a multicarrier system, provides very important and clear evidence that another hidden order, most likely the symmetry broken from the tetragonal C4 symmetry to the C2 symmetry nematicity associated with the selective d -orbital splitting, exists in the case of superconducting FeSe other than the AF magnetic order spin fluctuations. The intrinsic low-temperature phase in FeSe is in the almost compensated semimetallic states but is additionally accompanied by Dirac cone-like ultrafast electrons ˜104cm2(VS) -1 as minority carriers.

Anisotropic harmonic oscillator, non-commutative Landau problem and exotic Newton-Hooke symmetry

International Nuclear Information System (INIS)

Alvarez, Pedro D.; Gomis, Joaquim; Kamimura, Kiyoshi; Plyushchay, Mikhail S.

2008-01-01

We investigate the planar anisotropic harmonic oscillator with explicit rotational symmetry as a particle model with non-commutative coordinates. It includes the exotic Newton-Hooke particle and the non-commutative Landau problem as special, isotropic and maximally anisotropic, cases. The system is described by the same (2+1)-dimensional exotic Newton-Hooke symmetry as in the isotropic case, and develops three different phases depending on the values of the two central charges. The special cases of the exotic Newton-Hooke particle and non-commutative Landau problem are shown to be characterized by additional, so(3) or so(2,1) Lie symmetry, which reflects their peculiar spectral properties

Gravitation and Gauge Symmetries

CERN Document Server

Stewart, J

2002-01-01

The purpose of this book (I quote verbatim from the back cover) is to 'shed light upon the intrinsic structure of gravity and the principle of gauge invariance, which may lead to a consistent unified field theory', a very laudable aim. The content divides fairly clearly into four sections (and origins). After a brief introduction, chapters 2-6 review the 'Structure of gravity as a theory based on spacetime gauge symmetries'. This is fairly straightforward material, apparently based on a one-semester graduate course taught at the University of Belgrade for about two decades, and, by implication, this is a reasonably accurate description of its level and assumed knowledge. There follow two chapters of new material entitled 'Gravity in flat spacetime' and 'Nonlinear effects in gravity'. The final three chapters, entitled 'Supersymmetry and supergravity', 'Kaluza-Klein theory' and 'String theory' have been used for the basis of a one-semester graduate course on the unification of fundamental interactions. The boo...

A broken symmetry ontology: Quantum mechanics as a broken symmetry

International Nuclear Information System (INIS)

Buschmann, J.E.

1988-01-01

The author proposes a new broken symmetry ontology to be used to analyze the quantum domain. This ontology is motivated and grounded in a critical epistemological analysis, and an analysis of the basic role of symmetry in physics. Concurrently, he is led to consider nonheterogeneous systems, whose logical state space contains equivalence relations not associated with the causal relation. This allows him to find a generalized principle of symmetry and a generalized symmetry-conservation formalisms. In particular, he clarifies the role of Noether's theorem in field theory. He shows how a broken symmetry ontology already operates in a description of the weak interactions. Finally, by showing how a broken symmetry ontology operates in the quantum domain, he accounts for the interpretational problem and the essential incompleteness of quantum mechanics. He proposes that the broken symmetry underlying this ontological domain is broken dilation invariance

From physical symmetries to emergent gauge symmetries

International Nuclear Information System (INIS)

Barceló, Carlos; Carballo-Rubio, Raúl; Di Filippo, Francesco; Garay, Luis J.

2016-01-01

Gauge symmetries indicate redundancies in the description of the relevant degrees of freedom of a given field theory and restrict the nature of observable quantities. One of the problems faced by emergent theories of relativistic fields is to understand how gauge symmetries can show up in systems that contain no trace of these symmetries at a more fundamental level. In this paper we start a systematic study aimed to establish a satisfactory mathematical and physical picture of this issue, dealing first with abelian field theories. We discuss how the trivialization, due to the decoupling and lack of excitation of some degrees of freedom, of the Noether currents associated with physical symmetries leads to emergent gauge symmetries in specific situations. An example of a relativistic field theory of a vector field is worked out in detail in order to make explicit how this mechanism works and to clarify the physics behind it. The interplay of these ideas with well-known results of importance to the emergent gravity program, such as the Weinberg-Witten theorem, are discussed.

Field-theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology, and beyond.

Science.gov (United States)

Wang, Juven C; Gu, Zheng-Cheng; Wen, Xiao-Gang

2015-01-23

The challenge of identifying symmetry-protected topological states (SPTs) is due to their lack of symmetry-breaking order parameters and intrinsic topological orders. For this reason, it is impossible to formulate SPTs under Ginzburg-Landau theory or probe SPTs via fractionalized bulk excitations and topology-dependent ground state degeneracy. However, the partition functions from path integrals with various symmetry twists are universal SPT invariants, fully characterizing SPTs. In this work, we use gauge fields to represent those symmetry twists in closed spacetimes of any dimensionality and arbitrary topology. This allows us to express the SPT invariants in terms of continuum field theory. We show that SPT invariants of pure gauge actions describe the SPTs predicted by group cohomology, while the mixed gauge-gravity actions describe the beyond-group-cohomology SPTs. We find new examples of mixed gauge-gravity actions for U(1) SPTs in (4+1)D via the gravitational Chern-Simons term. Field theory representations of SPT invariants not only serve as tools for classifying SPTs, but also guide us in designing physical probes for them. In addition, our field theory representations are independently powerful for studying group cohomology within the mathematical context.

Intrinsic motivation towards sports in Singaporean students: the role of sport ability beliefs.

Science.gov (United States)

Wang, C K John; Biddle, Stuart J H

2003-09-01

This study investigated determinants of active lifestyles in Singaporean university students. Using confirmatory factor analysis, a measure of lay beliefs concerning athletic ability was confirmed. Other results confirmed hypotheses that beliefs reflecting that athletic ability can be developed over time (incremental beliefs) predict an achievement task (self-referenced) orientation, while beliefs reflecting that athletic ability is relatively stable (entity beliefs) predict an ego (other-person, comparative) orientation. Goal orientations directly affect perceived competence which, in turn, influence intrinsic motivation to be physically active. A task orientation had a direct link to intrinsic motivation. Results suggest that intrinsic motivation towards sport and physical activity might be enhanced through interventions that focus on self-referenced and self-improvement notions of ability as well as perceived competence.

Symmetry rules How science and nature are founded on symmetry

CERN Document Server

Rosen, Joe

2008-01-01

When we use science to describe and understand the world around us, we are in essence grasping nature through symmetry. In fact, modern theoretical physics suggests that symmetry is a, if not the, foundational principle of nature. Emphasizing the concepts, this book leads the reader coherently and comprehensively into the fertile field of symmetry and its applications. Among the most important applications considered are the fundamental forces of nature and the Universe. It is shown that the Universe cannot possess exact symmetry, which is a principle of fundamental significance. Curie's principle - which states that the symmetry of the effect is at least that of the cause - features prominently. An introduction to group theory, the mathematical language of symmetry, is included. This book will convince all interested readers of the importance of symmetry in science. Furthermore, it will serve as valuable background reading for all students in the physical sciences.

Noncritical generation of nonclassical frequency combs via spontaneous rotational symmetry breaking

Science.gov (United States)

Navarrete-Benlloch, Carlos; Patera, Giuseppe; de Valcárcel, Germán J.

2017-10-01

Synchronously pumped optical parametric oscillators (SPOPOs) are optical cavities driven by mode-locked lasers, and containing a nonlinear crystal capable of down-converting a frequency comb to lower frequencies. SPOPOs have received a lot of attention lately because their intrinsic multimode nature makes them compact sources of quantum correlated light with promising applications in modern quantum information technologies. In this work we show that SPOPOs are also capable of accessing the challenging and interesting regime where spontaneous symmetry breaking confers strong nonclassical properties to the emitted light, which has eluded experimental observation so far. Apart from opening the possibility of studying experimentally this elusive regime of dissipative phase transitions, our predictions will have a practical impact, since we show that spontaneous symmetry breaking provides a specific spatiotemporal mode with large quadrature squeezing for any value of the system parameters, turning SPOPOs into robust sources of highly nonclassical light above threshold.

Symmetries in nature

International Nuclear Information System (INIS)

Mainzer, K.

1988-01-01

Symmetry, disymmetry, chirality etc. are well-known topics in chemistry. But they cannot only be found on the molecular level of matter. Atoms and elementary particles in physics are also characterized by particular symmetry groups. Even living organisms and populations on the macroscopic level have functional properties of symmetry. The whole physical, chemical, and biological evolution seems to be regulated by the emergence of new symmetries and the breaking down of old ones. One is reminded of Heisenberg's famous statement: 'Die letzte Wurzel der Erscheinungen ist also nicht die Materie, sondern das mathematische Gesetz, die Symmetrie, die mathematische Form' (Wandlungen in den Grundlagen der Naturwissenschaften, 1959). Historically the belief in symmetry and simplicity of nature has a long philosophical tradition from the Pythagoreans, Plato and Greek astronomers to Kepler and modern scientists. Today, 'symmetries in nature' is a common topic of mathematics, physics, chemistry, and biology. A lot of Nobel prizes were given in honour of inquiries concerning symmetries in nature. The fascination of symmetries is not only motivated by science, but by art and religion too. Therefore 'symmetris in nature' is an interdisciplinary topic which may help to overcome C.P. Snow's 'Two Cultures' of natural sciences and humanities. (author) 17 refs., 21 figs

Symmetries in nature

Energy Technology Data Exchange (ETDEWEB)

Mainzer, K

1988-05-01

Symmetry, disymmetry, chirality etc. are well-known topics in chemistry. But they cannot only be found on the molecular level of matter. Atoms and elementary particles in physics are also characterized by particular symmetry groups. Even living organisms and populations on the macroscopic level have functional properties of symmetry. The whole physical, chemical, and biological evolution seems to be regulated by the emergence of new symmetries and the breaking down of old ones. One is reminded of Heisenberg's famous statement: 'Die letzte Wurzel der Erscheinungen ist also nicht die Materie, sondern das mathematische Gesetz, die Symmetrie, die mathematische Form' (Wandlungen in den Grundlagen der Naturwissenschaften, 1959). Historically the belief in symmetry and simplicity of nature has a long philosophical tradition from the Pythagoreans, Plato and Greek astronomers to Kepler and modern scientists. Today, 'symmetries in nature' is a common topic of mathematics, physics, chemistry, and biology. A lot of Nobel prizes were given in honour of inquiries concerning symmetries in nature. The fascination of symmetries is not only motivated by science, but by art and religion too. Therefore 'symmetris in nature' is an interdisciplinary topic which may help to overcome C.P. Snow's 'Two Cultures' of natural sciences and humanities. (author) 17 refs., 21 figs.

Symmetries in nuclei

International Nuclear Information System (INIS)

Arima, A.

2003-01-01

(1) There are symmetries in nature, and the concept of symmetry has been used in art and architecture. The symmetry is evaluated high in the European culture. In China, the symmetry is broken in the paintings but it is valued in the architecture. In Japan, however, the symmetry has been broken everywhere. The serious and interesting question is why these differences happens? (2) In this lecture, I reviewed from the very beginning the importance of the rotational symmetry in quantum mechanics. I am sorry to be too fundamental for specialists of nuclear physics. But for people who do not use these theories, I think that you could understand the mathematical aspects of quantum mechanics and the relation between the angular momentum and the rotational symmetry. (3) To the specialists of nuclear physics, I talked about my idea as follows: dynamical treatment of collective motions in nuclei by IBM, especially the meaning of the degeneracy observed in the rotation bands top of γ vibration and β vibration, and the origin of pseudo-spin symmetry. Namely, if there is a symmetry, a degeneracy occurs. Conversely, if there is a degeneracy, there must be a symmetry. I discussed some details of the observed evidence and this correspondence is my strong belief in physics. (author)

Symmetry control in subscale near-vacuum hohlraums

Science.gov (United States)

Turnbull, D.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Mackinnon, A.; Zylstra, A. B.; Rinderknecht, H. G.; Sio, H.; Petrasso, R. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J.

2016-05-01

Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

Symmetry control in subscale near-vacuum hohlraums

Energy Technology Data Exchange (ETDEWEB)

Turnbull, D., E-mail: turnbull2@llnl.gov; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J. [National Ignition Facility, LLNL, Livermore, California 94550 (United States); Mackinnon, A. [National Ignition Facility, LLNL, Livermore, California 94550 (United States); Linac Coherent Light Source, SLAC, Menlo Park, California 94025 (United States); Zylstra, A. B. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rinderknecht, H. G. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); National Ignition Facility, LLNL, Livermore, California 94550 (United States); Sio, H.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States)

2016-05-15

Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

Symmetry rules. How science and nature are founded on symmetry

Energy Technology Data Exchange (ETDEWEB)

Rosen, J.

2008-07-01

When we use science to describe and understand the world around us, we are in essence grasping nature through symmetry. In fact, modern theoretical physics suggests that symmetry is a, if not the, foundational principle of nature. Emphasizing the concepts, this book leads the reader coherently and comprehensively into the fertile field of symmetry and its applications. Among the most important applications considered are the fundamental forces of nature and the Universe. It is shown that the Universe cannot possess exact symmetry, which is a principle of fundamental significance. Curie's principle - which states that the symmetry of the effect is at least that of the cause - features prominently. An introduction to group theory, the mathematical language of symmetry, is included. This book will convince all interested readers of the importance of symmetry in science. Furthermore, it will serve as valuable background reading for all students in the physical sciences. (orig.)

Symmetries and nuclei

International Nuclear Information System (INIS)

Henley, E.M.

1987-01-01

Nuclei are very useful for testing symmetries, and for studies of symmetry breaking. This thesis is illustrated for two improper space-time transformations, parity and time-reversal and for one internal symmetry: charge symmetry and independence. Recent progress and present interest is reviewed. 23 refs., 8 figs., 2 tabs

Pairwise harmonics for shape analysis

KAUST Repository

Zheng, Youyi; Tai, Chiewlan; Zhang, Eugene; Xu, Pengfei

2013-01-01

efficient algorithms than the state-of-the-art methods for three applications: intrinsic reflectional symmetry axis computation, matching shape extremities, and simultaneous surface segmentation and skeletonization. © 2012 IEEE.

Hidden Structural Codes in Protein Intrinsic Disorder.

Science.gov (United States)

Borkosky, Silvia S; Camporeale, Gabriela; Chemes, Lucía B; Risso, Marikena; Noval, María Gabriela; Sánchez, Ignacio E; Alonso, Leonardo G; de Prat Gay, Gonzalo

2017-10-17

Intrinsic disorder is a major structural category in biology, accounting for more than 30% of coding regions across the domains of life, yet consists of conformational ensembles in equilibrium, a major challenge in protein chemistry. Anciently evolved papillomavirus genomes constitute an unparalleled case for sequence to structure-function correlation in cases in which there are no folded structures. E7, the major transforming oncoprotein of human papillomaviruses, is a paradigmatic example among the intrinsically disordered proteins. Analysis of a large number of sequences of the same viral protein allowed for the identification of a handful of residues with absolute conservation, scattered along the sequence of its N-terminal intrinsically disordered domain, which intriguingly are mostly leucine residues. Mutation of these led to a pronounced increase in both α-helix and β-sheet structural content, reflected by drastic effects on equilibrium propensities and oligomerization kinetics, and uncovers the existence of local structural elements that oppose canonical folding. These folding relays suggest the existence of yet undefined hidden structural codes behind intrinsic disorder in this model protein. Thus, evolution pinpoints conformational hot spots that could have not been identified by direct experimental methods for analyzing or perturbing the equilibrium of an intrinsically disordered protein ensemble.

Symmetry-protected topological superfluids and superconductors. From the basics to 3He

International Nuclear Information System (INIS)

Mizushima, Takeshi; Tsutsumi, Yasumasa; Kawakami, Takuto; Sato, Masatoshi; Ichioka, Masanori; Machida, Kazushige

2016-01-01

In this article, we give a comprehensive review of recent progress in research on symmetry-protected topological superfluids and topological crystalline superconductors, and their physical consequences such as helical and chiral Majorana fermions. We start this review article with the minimal model that captures the essence of such topological materials. The central part of this article is devoted to the superfluid 3 He, which serves as a rich repository of novel topological quantum phenomena originating from the intertwining of symmetries and topologies. In particular, it is emphasized that the quantum fluid confined to nanofabricated geometries possesses multiple superfluid phases composed of the symmetry-protected topological superfluid B-phase, the A-phase as a Weyl superfluid, the nodal planar and polar phases, and the crystalline ordered stripe phase. All these phases generate noteworthy topological phenomena, including topological phase transitions concomitant with spontaneous symmetry breaking, Majorana fermions, Weyl superfluidity, emergent supersymmetry, spontaneous edge mass and spin currents, topological Fermi arcs, and exotic quasiparticles bound to topological defects. In relation to the mass current carried by gapless edge states, we also briefly review a longstanding issue on the intrinsic angular momentum paradox in 3 He-A. Moreover, we share the current status of our knowledge on the topological aspects of unconventional superconductors, such as the heavy-fermion superconductor UPt 3 and superconducting doped topological insulators, in connection with the superfluid 3 He. (author)

The Graph, Geometry and Symmetries of the Genetic Code with Hamming Metric

Directory of Open Access Journals (Sweden)

Reijer Lenstra

2015-07-01

Full Text Available The similarity patterns of the genetic code result from similar codons encoding similar messages. We develop a new mathematical model to analyze these patterns. The physicochemical characteristics of amino acids objectively quantify their differences and similarities; the Hamming metric does the same for the 64 codons of the codon set. (Hamming distances equal the number of different codon positions: AAA and AAC are at 1-distance; codons are maximally at 3-distance. The CodonPolytope, a 9-dimensional geometric object, is spanned by 64 vertices that represent the codons and the Euclidian distances between these vertices correspond one-to-one with intercodon Hamming distances. The CodonGraph represents the vertices and edges of the polytope; each edge equals a Hamming 1-distance. The mirror reflection symmetry group of the polytope is isomorphic to the largest permutation symmetry group of the codon set that preserves Hamming distances. These groups contain 82,944 symmetries. Many polytope symmetries coincide with the degeneracy and similarity patterns of the genetic code. These code symmetries are strongly related with the face structure of the polytope with smaller faces displaying stronger code symmetries. Splitting the polytope stepwise into smaller faces models an early evolution of the code that generates this hierarchy of code symmetries. The canonical code represents a class of 41,472 codes with equivalent symmetries; a single class among an astronomical number of symmetry classes comprising all possible codes.

Symmetries in nature the scientific heritage of Louis Michel

CERN Document Server

Todorov, Ivan; Zhilinskii, Boris

2014-01-01

Reflecting the oeuvre of “a man of two cultures: the culture of pure mathematics and the culture of theoretical physics” (in the words of his long time friend and co-author, Kameshwar Wali), this volume is centred around the notion of symmetry and its breaking. Starting with particle physics, the content proceeds to symmetries of matter, defects, and crystals. The mathematics of group extensions, non-linear group action, critical orbits and phase transitions is developed along the way. The symmetry principles and general mathematical tools provide unity in the treatment of different topics. The papers and lecture notes are preceded by a lively biography of Louis Michel and a commentary that relates his selected works both to the physics of his time and to contemporary trends. This book should be of interest to theoretical physicists, chemists, applied mathematicians and historians of science, and is accessible to graduate (and advanced undergraduate) students.

Left-right gauge symmetry breaking by radiative corrections in supergravity

International Nuclear Information System (INIS)

Moxhay, P.; Yamamoto, K.

1984-01-01

A supersymmetric SU(2)sub(L) x SU(2)sub(R) x U(1)sub(B-L) gauge theory coupled to N = 1 supergravity is investigated. The scale of left-right gauge symmetry breaking is determined as Msub(R) proportional Msub(P) esup(-1/α) by radiative corrections through the logarithmic evolution of soft supersymmetry breakings. SU(2)sub(L) x SU(2)sub(R) x U(1)sub(B-L) may be embedded in SO(10) grand unification. Cosmological implications intrinsic to the present model are also discussed, which may give a constraint Msub(R) approx.= 10 9-12 GeV. (orig.)

Some symmetries in nuclei

International Nuclear Information System (INIS)

Henley, E.M.

1981-09-01

Internal and space-time symmetries are discussed in this group of lectures. The first of the lectures deals with an internal symmetry, or rather two related symmetries called charge independence and charge symmetry. The next two discuss space-time symmetries which also hold approximately, but are broken only by the weak forces; that is, these symmetries hold for both the hadronic and electromagnetic forces

The Novel Quantitative Technique for Assessment of Gait Symmetry Using Advanced Statistical Learning Algorithm

OpenAIRE

Wu, Jianning; Wu, Bin

2015-01-01

The accurate identification of gait asymmetry is very beneficial to the assessment of at-risk gait in the clinical applications. This paper investigated the application of classification method based on statistical learning algorithm to quantify gait symmetry based on the assumption that the degree of intrinsic change in dynamical system of gait is associated with the different statistical distributions between gait variables from left-right side of lower limbs; that is, the discrimination of...

Generalized global symmetries

International Nuclear Information System (INIS)

Gaiotto, Davide; Kapustin, Anton; Seiberg, Nathan; Willett, Brian

2015-01-01

A q-form global symmetry is a global symmetry for which the charged operators are of space-time dimension q; e.g. Wilson lines, surface defects, etc., and the charged excitations have q spatial dimensions; e.g. strings, membranes, etc. Many of the properties of ordinary global symmetries (q=0) apply here. They lead to Ward identities and hence to selection rules on amplitudes. Such global symmetries can be coupled to classical background fields and they can be gauged by summing over these classical fields. These generalized global symmetries can be spontaneously broken (either completely or to a subgroup). They can also have ’t Hooft anomalies, which prevent us from gauging them, but lead to ’t Hooft anomaly matching conditions. Such anomalies can also lead to anomaly inflow on various defects and exotic Symmetry Protected Topological phases. Our analysis of these symmetries gives a new unified perspective of many known phenomena and uncovers new results.

Global gyrokinetic simulations of intrinsic rotation in ASDEX Upgrade Ohmic L-mode plasmas

Science.gov (United States)

Hornsby, W. A.; Angioni, C.; Lu, Z. X.; Fable, E.; Erofeev, I.; McDermott, R.; Medvedeva, A.; Lebschy, A.; Peeters, A. G.; The ASDEX Upgrade Team

2018-05-01

Non-linear, radially global, turbulence simulations of ASDEX Upgrade (AUG) plasmas are performed and the nonlinear generated intrinsic flow shows agreement with the intrinsic flow gradients measured in the core of Ohmic L-mode plasmas at nominal parameters. Simulations utilising the kinetic electron model show hollow intrinsic flow profiles as seen in a predominant number of experiments performed at similar plasma parameters. In addition, significantly larger flow gradients are seen than in a previous flux-tube analysis (Hornsby et al 2017 Nucl. Fusion 57 046008). Adiabatic electron model simulations can show a flow profile with opposing sign in the gradient with respect to a kinetic electron simulation, implying a reversal in the sign of the residual stress due to kinetic electrons. The shaping of the intrinsic flow is strongly determined by the density gradient profile. The sensitivity of the residual stress to variations in density profile curvature is calculated and seen to be significantly stronger than to neoclassical flows (Hornsby et al 2017 Nucl. Fusion 57 046008). This variation is strong enough on its own to explain the large variations in the intrinsic flow gradients seen in some AUG experiments. Analysis of the symmetry breaking properties of the turbulence shows that profile shearing is the dominant mechanism in producing a finite parallel wave-number, with turbulence gradient effects contributing a smaller portion of the parallel wave-vector.

Unconventional Topological Phase Transition in Two-Dimensional Systems with Space-Time Inversion Symmetry

Science.gov (United States)

Ahn, Junyeong; Yang, Bohm-Jung

2017-04-01

We study a topological phase transition between a normal insulator and a quantum spin Hall insulator in two-dimensional (2D) systems with time-reversal and twofold rotation symmetries. Contrary to the case of ordinary time-reversal invariant systems, where a direct transition between two insulators is generally predicted, we find that the topological phase transition in systems with an additional twofold rotation symmetry is mediated by an emergent stable 2D Weyl semimetal phase between two insulators. Here the central role is played by the so-called space-time inversion symmetry, the combination of time-reversal and twofold rotation symmetries, which guarantees the quantization of the Berry phase around a 2D Weyl point even in the presence of strong spin-orbit coupling. Pair creation and pair annihilation of Weyl points accompanying partner exchange between different pairs induces a jump of a 2D Z2 topological invariant leading to a topological phase transition. According to our theory, the topological phase transition in HgTe /CdTe quantum well structure is mediated by a stable 2D Weyl semimetal phase because the quantum well, lacking inversion symmetry intrinsically, has twofold rotation about the growth direction. Namely, the HgTe /CdTe quantum well can show 2D Weyl semimetallic behavior within a small but finite interval in the thickness of HgTe layers between a normal insulator and a quantum spin Hall insulator. We also propose that few-layer black phosphorus under perpendicular electric field is another candidate system to observe the unconventional topological phase transition mechanism accompanied by the emerging 2D Weyl semimetal phase protected by space-time inversion symmetry.

Comment to: "Particle-hole symmetry breaking in the pseudogap state of Bi2201"

OpenAIRE

Panas, Itai

2010-01-01

Shen et al. [1] recently reported on ARPES data from Pb-Bi2201 revealing both particle-hole symmetry breaking and pronounced spectral broadening, which they interpret to be indicative of spatial symmetry breaking without long-range order at the opening of the pseudogap. Here is demonstrated how their results could be interpreted to reflect static and dynamic inhomogeneous crystal fields causing inter-band transfer of holes upon cooling below T*. Possible relevance to formation of charge carri...

An experimental study of symmetry lowering of analcime

Science.gov (United States)

Sugano, Neo; Kyono, Atsushi

2018-04-01

Single crystals of analcime were hydrothermally synthesized from a gel of analcime composition at 200 °C for 24 h. They were grown up to 100 μm in size with typical deltoidal icositetrahedron habit. The chemical composition determined by EPMA and TG analyses was Na0.84(Al0.89Si2.12)O6·1.04H2O. The single-crystal X-ray diffraction method was used to determine the symmetry and crystal structure of analcime. The analcime grown from a gel crystallized in cubic space group Ia3 d with lattice parameter a = 13.713(3) Å. In the cubic analcime, Si and Al cations were totally disordered over the framework T sites with site occupancy of Si:Al = 0.6871:0.3129(14). The single crystals of analcime with cubic symmetry were hydrothermally reheated at 200 °C in ultrapure water. After the hydrothermal treatment for 24 h, forbidden reflections for the cubic Ia3 d symmetry were observed. The reflection conditions led to an orthorhombic space group Ibca with lattice parameters a = 13.727(2) Å, b = 13.707(2) Å, and c = 13.707(2) Å. The unit-cell showed a slight distortion with ( a + b)/2 > c, yielding a flattened cell along c. In the orthorhombic analcime, Al exhibited a site preference for T11 site, which indicates that the Si/Al ordering over the framework T sites lowers the symmetry from cubic Ia3 d to orthorhombic Ibca. After the hydrothermal treatment for 48 h, reflections corresponding to orthorhombic space group Ibca were observed as well. The lattice parameters were a = 13.705(2) Å, b = 13.717(2) Å, and c = 13.706(2) Å, retaining the flattened cell shape with ( a + b)/2 > c. The Si and Al cations were further ordered among the framework T sites than the case of the hydrothermal treatment for 24 h. As a consequence, the Si/Al ordering was slightly but significantly accelerated with increasing the hydrothermal treatment time. During the hydrothermal reaction, however, chemical compositions were almost unchanged. The site occupancies of Na over the extra-framework sites

Symmetry in running.

Science.gov (United States)

Raibert, M H

1986-03-14

Symmetry plays a key role in simplifying the control of legged robots and in giving them the ability to run and balance. The symmetries studied describe motion of the body and legs in terms of even and odd functions of time. A legged system running with these symmetries travels with a fixed forward speed and a stable upright posture. The symmetries used for controlling legged robots may help in elucidating the legged behavior of animals. Measurements of running in the cat and human show that the feet and body sometimes move as predicted by the even and odd symmetry functions.

Intrinsic non-inductive current driven by ETG turbulence in tokamaks

Science.gov (United States)

Singh, Rameswar; Kaw, P. K.; Singh, R.; Gürcan, Ã.-. D.

2017-10-01

Motivated by observations and physics understanding of the phenomenon of intrinsic rotation, it is suggested that similar considerations for electron dynamics may result in intrinsic current in tokamaks. We have investigated the possibility of intrinsic non-inductive current in the turbulent plasma of tokamaks. Ohm's law is generalized to include the effect of turbulent fluctuations in the mean field approach. This clearly leads to the identification of sources and the mechanisms of non-inductive current drive by electron temperature gradient turbulence. It is found that a mean parallel electro-motive force and hence a mean parallel current can be generated by (1) the divergence of residual current flux density and (2) a non-flux like turbulent source from the density and parallel electric field correlations. Both residual flux and the non-flux source require parallel wave-number k∥ symmetry breaking for their survival which can be supplied by various means like mean E × B shear, turbulence intensity gradient, etc. Estimates of turbulence driven current are compared with the background bootstrap current in the pedestal region. It is found that turbulence driven current is nearly 10% of the bootstrap current and hence can have a significant influence on the equilibrium current density profiles and current shear driven modes.

Intrinsic Ambipolarity and Rotation in Stellarators

International Nuclear Information System (INIS)

Helander, P.; Simakov, A. N.

2008-01-01

It is shown that collisional plasma transport is intrinsically ambipolar only in quasiaxisymmetric or quasihelically symmetric magnetic configurations. Only in such fields can the plasma rotate freely, and then only in the direction of quasisymmetry. In a non-quasi-symmetric magnetic field, the average radial electric field is determined by parallel viscosity, which in turn is usually governed by collisional processes. Locally, the radial electric field may be affected by turbulent Reynolds stress producing zonal flows, but on a radial average taken over several ion gyroradii, it is determined by parallel viscosity, at least if the turbulence is electrostatic and obeys the conventional gyrokinetic orderings. This differs from the situation in a tokamak, where there is no flow damping by parallel viscosity in the symmetry direction and the turbulent Reynolds stress may affect the global radial electric field

Observation of narrowband intrinsic spectra of Brillouin dynamic gratings.

Science.gov (United States)

Song, Kwang Yong; Yoon, Hyuk Jin

2010-09-01

We experimentally demonstrate that the reflection spectrum of a Brillouin dynamic grating in a polarization-maintaining fiber can be much narrower than the intrinsic linewidth of the stimulated Brillouin scattering, matching well with the theory of a fiber Bragg grating in terms of the linewidth and the reflectivity. A 3 dB bandwidth as narrow as 10.5 MHz is observed with the Brillouin dynamic grating generated in a 9 m uniform fiber.

Quantitative facial asymmetry: using three-dimensional photogrammetry to measure baseline facial surface symmetry.

Science.gov (United States)

Taylor, Helena O; Morrison, Clinton S; Linden, Olivia; Phillips, Benjamin; Chang, Johnny; Byrne, Margaret E; Sullivan, Stephen R; Forrest, Christopher R

2014-01-01

Although symmetry is hailed as a fundamental goal of aesthetic and reconstructive surgery, our tools for measuring this outcome have been limited and subjective. With the advent of three-dimensional photogrammetry, surface geometry can be captured, manipulated, and measured quantitatively. Until now, few normative data existed with regard to facial surface symmetry. Here, we present a method for reproducibly calculating overall facial symmetry and present normative data on 100 subjects. We enrolled 100 volunteers who underwent three-dimensional photogrammetry of their faces in repose. We collected demographic data on age, sex, and race and subjectively scored facial symmetry. We calculated the root mean square deviation (RMSD) between the native and reflected faces, reflecting about a plane of maximum symmetry. We analyzed the interobserver reliability of the subjective assessment of facial asymmetry and the quantitative measurements and compared the subjective and objective values. We also classified areas of greatest asymmetry as localized to the upper, middle, or lower facial thirds. This cluster of normative data was compared with a group of patients with subtle but increasing amounts of facial asymmetry. We imaged 100 subjects by three-dimensional photogrammetry. There was a poor interobserver correlation between subjective assessments of asymmetry (r = 0.56). There was a high interobserver reliability for quantitative measurements of facial symmetry RMSD calculations (r = 0.91-0.95). The mean RMSD for this normative population was found to be 0.80 ± 0.24 mm. Areas of greatest asymmetry were distributed as follows: 10% upper facial third, 49% central facial third, and 41% lower facial third. Precise measurement permitted discrimination of subtle facial asymmetry within this normative group and distinguished norms from patients with subtle facial asymmetry, with placement of RMSDs along an asymmetry ruler. Facial surface symmetry, which is poorly assessed

The symmetry of man.

Science.gov (United States)

Ermolenko, Alexander E; Perepada, Elena A

2007-01-01

The paper contains a description of basic regularities in the manifestation of symmetry of human structural organization and its ontogenetic and phylogenetic development. A concept of macrobiocrystalloid with inherent complex symmetry is proposed for the description of the human organism in its integrity. The symmetry can be characterized as two-plane radial (quadrilateral), where the planar symmetry is predominant while the layout of organs of radial symmetry is subordinated to it. Out of the two planes of symmetry (sagittal and horizontal), the sagittal plane is predominant. The symmetry of the chromosome, of the embrio at the early stages of cell cleavage as well as of some organs and systems in their phylogenetic development is described. An hypothesis is postulated that the two-plane symmetry is formed by two mechanisms: a) the impact of morphogenetic fields of the whole crystalloid organism during embriogenesis and, b) genetic mechanisms of the development of chromosomes having two-plane symmetry.

Experimental demonstration of an up-down asymmetry effect on intrinsic rotation in the TCV tokamak

International Nuclear Information System (INIS)

Camenen, Y; Peeters, A G; Casson, F J; Hornsby, W A; Snodin, A P; Szepesi, G; Bortolon, A; Duval, B P; Federspiel, L; Karpushov, A N; Piras, F; Sauter, O

2010-01-01

A new mechanism has recently been proposed that generates a radial flux of parallel momentum in toroidal plasmas. Namely, by considering up-down asymmetric flux surfaces, the symmetry following the magnetic field can be broken and an additional contribution to the turbulent momentum flux arises, potentially changing the intrinsic rotation profile. These predictions are tested with specific experiments on TCV. The intrinsic toroidal rotation is observed to change by roughly a factor of two when changing the up-down asymmetry of the plasma. More precisely, the toroidal rotation gradient changes in the outer part of the plasma, where the flux surface asymmetry is the highest. The experiments were performed for all combinations of the toroidal magnetic field and plasma current directions, that affect the sign of the predicted up-down asymmetry flux. In each case the variation of the intrinsic rotation profile with the up-down asymmetry is observed in the direction predicted by the theory.

Symmetry, Symmetry Breaking and Topology

Directory of Open Access Journals (Sweden)

Siddhartha Sen

2010-07-01

Full Text Available The ground state of a system with symmetry can be described by a group G. This symmetry group G can be discrete or continuous. Thus for a crystal G is a finite group while for the vacuum state of a grand unified theory G is a continuous Lie group. The ground state symmetry described by G can change spontaneously from G to one of its subgroups H as the external parameters of the system are modified. Such a macroscopic change of the ground state symmetry of a system from G to H correspond to a “phase transition”. Such phase transitions have been extensively studied within a framework due to Landau. A vast range of systems can be described using Landau’s approach, however there are also systems where the framework does not work. Recently there has been growing interest in looking at such non-Landau type of phase transitions. For instance there are several “quantum phase transitions” that are not of the Landau type. In this short review we first describe a refined version of Landau’s approach in which topological ideas are used together with group theory. The combined use of group theory and topological arguments allows us to determine selection rule which forbid transitions from G to certain of its subgroups. We end by making a few brief remarks about non-Landau type of phase transition.

Symmetry and electromagnetism

International Nuclear Information System (INIS)

Fuentes Cobas, L.E.; Font Hernandez, R.

1993-01-01

An analytical treatment of electrostatic and magnetostatic field symmetry, as a function of charge and current distribution symmetry, is proposed. The Newmann Principle, related to the cause-effect symmetry relation, is presented and applied to the characterization of simple configurations. (Author) 5 refs

A Nodal-independent and tissue-intrinsic mechanism controls heart-looping chirality

Science.gov (United States)

Noël, Emily S.; Verhoeven, Manon; Lagendijk, Anne Karine; Tessadori, Federico; Smith, Kelly; Choorapoikayil, Suma; den Hertog, Jeroen; Bakkers, Jeroen

2013-11-01

Breaking left-right symmetry in bilateria is a major event during embryo development that is required for asymmetric organ position, directional organ looping and lateralized organ function in the adult. Asymmetric expression of Nodal-related genes is hypothesized to be the driving force behind regulation of organ laterality. Here we identify a Nodal-independent mechanism that drives asymmetric heart looping in zebrafish embryos. In a unique mutant defective for the Nodal-related southpaw gene, preferential dextral looping in the heart is maintained, whereas gut and brain asymmetries are randomized. As genetic and pharmacological inhibition of Nodal signalling does not abolish heart asymmetry, a yet undiscovered mechanism controls heart chirality. This mechanism is tissue intrinsic, as explanted hearts maintain ex vivo retain chiral looping behaviour and require actin polymerization and myosin II activity. We find that Nodal signalling regulates actin gene expression, supporting a model in which Nodal signalling amplifies this tissue-intrinsic mechanism of heart looping.

Sutherland models for complex reflection groups

International Nuclear Information System (INIS)

Crampe, N.; Young, C.A.S.

2008-01-01

There are known to be integrable Sutherland models associated to every real root system, or, which is almost equivalent, to every real reflection group. Real reflection groups are special cases of complex reflection groups. In this paper we associate certain integrable Sutherland models to the classical family of complex reflection groups. Internal degrees of freedom are introduced, defining dynamical spin chains, and the freezing limit taken to obtain static chains of Haldane-Shastry type. By considering the relation of these models to the usual BC N case, we are led to systems with both real and complex reflection groups as symmetries. We demonstrate their integrability by means of new Dunkl operators, associated to wreath products of dihedral groups

Intrinsic localized modes in arrays of atomic-molecular Bose-Einstein condensates

International Nuclear Information System (INIS)

Abdullaev, F.Kh.; Konotop, V.V.

2003-01-01

The existence of strongly localized matter solitons, intrinsic localized modes (ILM's), in an array of atomic-molecular Bose-Einstein condensates (AMBEC's) is shown. The theory is based on the Wannier function expansion of the system order parameter and predicts the possibility of strong localization of the atomic and molecular components whose relative populations are determined by the Raman detuning parameter and by the atom-molecule conversion rate. ILM's can possess different symmetries and spatial distributions of the components. In this context AMBEC arrays can be viewed as potential compressors and separators of atomic and molecular condensates

From affine Hecke algebras to boundary symmetries

International Nuclear Information System (INIS)

Doikou, Anastasia

2005-01-01

Motivated by earlier works we employ appropriate realizations of the affine Hecke algebra and we recover previously known non-diagonal solutions of the reflection equation for the U q (gl n -bar ) case. The corresponding N site spin chain with open boundary conditions is then constructed and boundary non-local charges associated to the non-diagonal solutions of the reflection equation are derived, as coproduct realizations of the reflection algebra. With the help of linear intertwining relations involving the aforementioned solutions of the reflection equation, the symmetry of the open spin chain with the corresponding boundary conditions is exhibited, being essentially a remnant of the U q (gl n -bar ) algebra. More specifically, we show that representations of certain boundary non-local charges commute with the generators of the affine Hecke algebra and with the local Hamiltonian of the open spin chain for a particular choice of boundary conditions. Furthermore, we are able to show that the transfer matrix of the open spin chain commutes with a certain number of boundary non-local charges, depending on the choice of boundary conditions

The symmetry, misalignment and kinematic evolution of double radio sources

International Nuclear Information System (INIS)

Macklin, J.T.

1981-01-01

The symmetry properties of a carefully selected sample of 76 double radio sources have been examined. It is found that: (1) The average intrinsic misalignment (the ratio of the displacement of the optical object to the source size, before projection) of these sources is 0.038, independent of the intrinsic size; (2) sources which are most misaligned tend to have the highest values of D, the ratio of hot-spot separations from the nucleus; (3) hot spots are more asymmetric in brightness than are tails; and (4) the relative brightness of hot spots is not correlated with D, but the relation between D and F, the ratio of total flux densities in components, implies that most of the diffuse structure tends to be associated with the hot spot closer to the optical identification. Computer simulations have been used to examine (2); this is best explained if the major contribution to the D distribution is independent of orientation and is correlated with the intrinsic misalignment. It is shown that (2) is in conflict with the hypothesis that motion of the parent galaxy relative to the intergalactic medium makes the dominant contribution to the observed misalignment. (3) and (4) can be explained in terms of a beam model of double radio sources which includes the effects of the external environment. (author)

Efficient Symmetry Reduction and the Use of State Symmetries for Symbolic Model Checking

Directory of Open Access Journals (Sweden)

Christian Appold

2010-06-01

Full Text Available One technique to reduce the state-space explosion problem in temporal logic model checking is symmetry reduction. The combination of symmetry reduction and symbolic model checking by using BDDs suffered a long time from the prohibitively large BDD for the orbit relation. Dynamic symmetry reduction calculates representatives of equivalence classes of states dynamically and thus avoids the construction of the orbit relation. In this paper, we present a new efficient model checking algorithm based on dynamic symmetry reduction. Our experiments show that the algorithm is very fast and allows the verification of larger systems. We additionally implemented the use of state symmetries for symbolic symmetry reduction. To our knowledge we are the first who investigated state symmetries in combination with BDD based symbolic model checking.

Duality symmetry of N=4 Yang-Mills theory on T3

International Nuclear Information System (INIS)

Hacquebord, F.; Verlinde, H.

1997-01-01

We study the spectrum of BPS states in N=4 supersymmetric U(N) Yang-Mills theory. This theory has been proposed to describe M-theory on T 3 in the discrete light-cone formalism. We find that the degeneracy of irreducible BPS bound states in this model exhibits a (partially hidden) SL(5,Z) duality symmetry. Besides the electro-magnetic symmetry, this duality group also contains Nahm-like transformations that interchange the rank N of the gauge group with some of the magnetic or electric fluxes. In the M-theory interpretation, this mapping amounts to a reflection that interchanges the longitudinal direction with one of the transverse directions. (orig.)

Gauge symmetry breaking

International Nuclear Information System (INIS)

Weinberg, S.

1976-01-01

The problem of how gauge symmetries of the weak interactions get broken is discussed. Some reasons why such a heirarchy of gauge symmetry breaking is needed, the reason gauge heirarchies do not seem to arise in theories of a given and related type, and the implications of theories with dynamical symmetry breaking, which can exhibit a gauge hierarchy

Symmetry-breaking solutions of the Hubbard model

International Nuclear Information System (INIS)

Kuzemsky, A.L.; )

1998-10-01

The problem of finding the ferromagnetic and antiferromagnetic ''broken symmetry'' solutions of the correlated lattice fermion models beyond the mean-field approximation has been investigated. The calculation of the quasiparticle excitation spectrum with damping for the single- and multi-orbital Hubbard model has been performed in the framework of the equation-of-motion method for two-time temperature Green's Functions within a non-perturbative approach. A unified scheme for the construction of Generalised Mean Fields (elastic scattering corrections) and self-energy (inelastic scattering) in terms of Dyson equation has been generalised in order to include the presence of the ''source fields''. The damping of quasiparticles, which reflects the interaction of the single-particle and collective degrees of freedom has been calculated. The ''broken symmetry'' dynamical solutions of the Hubbard model, which correspond to various types of itinerant antiferromagnetism have been discussed. This approach complements previous studies and clarifies the nature of the concepts of itinerant antiferromagnetism and ''spin-aligning field'' of correlated lattice fermions. (author)

Monitoring of living cell attachment and spreading using reverse symmetry waveguide sensing

DEFF Research Database (Denmark)

Horvath, R.; Pedersen, H.C.; Skivesen, N.

2005-01-01

The effect of the attachment and spreading of living cells on the modes of a grating coupled reverse symmetry waveguide sensor is investigated in real time. The reverse symmetry design has an increased probing depth into the sample making it well suited for the monitoring of cell morphology....... As a result, significant changes in the incoupling peak height and peak shape were observed during cell attachment and spreading. It is suggested that the area under the incoupling peaks reflects the initial cell attachment process, while the mean peak position is mostly governed by the spreading of the cells...

Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

Science.gov (United States)

Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

2014-06-13

We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

Parastatistics and gauge symmetries

International Nuclear Information System (INIS)

Govorkov, A.B.

1982-01-01

A possible formulation of gauge symmetries in the Green parafield theory is analysed and the SO(3) gauge symmetry is shown to be on a distinct status. The Greenberg paraquark hypothesis turns out to be not equivalent to the hypothesis of quark colour SU(3)sub(c) symmetry. Specific features of the gauge SO(3) symmetry are discussed, and a possible scheme where it is an exact subgroup of the broken SU(3)sub(c) symmetry is proposed. The direct formulation of the gauge principle for the parafield represented by quaternions is also discussed

Chemical bonding analysis for solid-state systems using intrinsic oriented quasiatomic minimal-basis-set orbitals

International Nuclear Information System (INIS)

Yao, Y.X.; Wang, C.Z.; Ho, K.M.

2010-01-01

A chemical bonding scheme is presented for the analysis of solid-state systems. The scheme is based on the intrinsic oriented quasiatomic minimal-basis-set orbitals (IO-QUAMBOs) previously developed by Ivanic and Ruedenberg for molecular systems. In the solid-state scheme, IO-QUAMBOs are generated by a unitary transformation of the quasiatomic orbitals located at each site of the system with the criteria of maximizing the sum of the fourth power of interatomic orbital bond order. Possible bonding and antibonding characters are indicated by the single particle matrix elements, and can be further examined by the projected density of states. We demonstrate the method by applications to graphene and (6,0) zigzag carbon nanotube. The oriented-orbital scheme automatically describes the system in terms of sp 2 hybridization. The effect of curvature on the electronic structure of the zigzag carbon nanotube is also manifested in the deformation of the intrinsic oriented orbitals as well as a breaking of symmetry leading to nonzero single particle density matrix elements. In an additional study, the analysis is performed on the Al 3 V compound. The main covalent bonding characters are identified in a straightforward way without resorting to the symmetry analysis. Our method provides a general way for chemical bonding analysis of ab initio electronic structure calculations with any type of basis sets.

Conformal Symmetry as a Template for QCD

Energy Technology Data Exchange (ETDEWEB)

Brodsky, S

2004-08-04

Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero {beta} function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as {tau} decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized.

Conformal Symmetry as a Template for QCD

International Nuclear Information System (INIS)

Brodsky, S

2004-01-01

Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero β function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as τ decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized

THE LIMITED EFFECT OF COINCIDENT ORIENTATION ON THE CHOICE OF INTRINSIC AXIS (.).

Science.gov (United States)

Li, Jing; Su, Wei

2015-06-01

The allocentric system computes and represents general object-to-object spatial relationships to provide a spatial frame of reference other than the egocentric system. The intrinsic frame-of-reference system theory, which suggests people learn the locations of objects based upon an intrinsic axis, is important in research about the allocentric system. The purpose of the current study was to determine whether the effect of coincident orientation on the choice of intrinsic axis was limited. Two groups of participants (24 men, 24 women; M age = 24 yr., SD = 2) encoded different spatial layouts in which the objects shared the coincident orientation of 315° and 225° separately at learning perspective (0°). The response pattern of partial-scene-recognition task following learning reflected different strategies for choosing the intrinsic axis under different conditions. Under the 315° object-orientation condition, the objects' coincident orientation was as important as the symmetric axis in the choice of the intrinsic axis. However, participants were more likely to choose the symmetric axis as the intrinsic axis under the 225° object-orientation condition. The results suggest the effect of coincident orientation on the choice of intrinsic axis is limited.

Streamwise-Localized Solutions with natural 1-fold symmetry

Science.gov (United States)

Altmeyer, Sebastian; Willis, Ashley; Hof, Björn

2014-11-01

It has been proposed in recent years that turbulence is organized around unstable invariant solutions, which provide the building blocks of the chaotic dynamics. In direct numerical simulations of pipe flow we show that when imposing a minimal symmetry constraint (reflection in an axial plane only) the formation of turbulence can indeed be explained by dynamical systems concepts. The hypersurface separating laminar from turbulent motion, the edge of turbulence, is spanned by the stable manifolds of an exact invariant solution, a periodic orbit of a spatially localized structure. The turbulent states themselves (turbulent puffs in this case) are shown to arise in a bifurcation sequence from a related localized solution (the upper branch orbit). The rather complex bifurcation sequence involves secondary Hopf bifurcations, frequency locking and a period doubling cascade until eventually turbulent puffs arise. In addition we report preliminary results of the transition sequence for pipe flow without symmetry constraints.

Origin of family symmetries

International Nuclear Information System (INIS)

Nilles, Hans Peter

2012-04-01

Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.

Origin of family symmetries

Energy Technology Data Exchange (ETDEWEB)

Nilles, Hans Peter [Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Bonn Univ. (Germany). Physikalisches Inst.; Ratz, Michael [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-04-15

Discrete (family) symmetries might play an important role in models of elementary particle physics. We discuss the origin of such symmetries in the framework of consistent ultraviolet completions of the standard model in field and string theory. The symmetries can arise due to special geometrical properties of extra compact dimensions and the localization of fields in this geometrical landscape. We also comment on anomaly constraints for discrete symmetries.

Optical metamaterials with quasicrystalline symmetry: symmetry-induced optical isotropy

International Nuclear Information System (INIS)

Kruk, S.S.; Decker, M.; Helgert, Ch.; Neshev, D.N.; Kivshar, Y.S.; Staude, I.; Powell, D.A.; Pertsch, Th.; Menzel, Ch.; Helgert, Ch.; Etrich, Ch.; Rockstuhl, C.; Menzel, Ch.

2013-01-01

Taking advantage of symmetry considerations, we have analyzed the potential of various metamaterials to affect the polarization state of light upon oblique illumination. We have shown that depending on the angle of illumination, metamaterials are able to support specific polarization states. The presented methodology that using ellipticity and circular dichroism, provides an unambiguous language for discussing the impact of the inherent symmetry of the metamaterial lattices on their far-field response. Our findings allow the quantification analysis of the impact of inter-element coupling and lattice symmetry on the optical properties of metamaterials, and to separate this contribution from the response associated with a single meta-atom. In addition, we have studied the concept of optical quasicrystalline metamaterials, revealing that the absence of translational symmetry (periodicity) of quasicrystalline metamaterials causes an isotropic optical response, while the long-range positional order preserves the resonance properties. Our findings constitute an important step towards the design of optically isotropic metamaterials and metasurfaces. (authors)

Fluid relabelling symmetries, Lie point symmetries and the Lagrangian map in magnetohydrodynamics and gas dynamics

International Nuclear Information System (INIS)

Webb, G M; Zank, G P

2007-01-01

We explore the role of the Lagrangian map for Lie symmetries in magnetohydrodynamics (MHD) and gas dynamics. By converting the Eulerian Lie point symmetries of the Galilei group to Lagrange label space, in which the Eulerian position coordinate x is regarded as a function of the Lagrange fluid labels x 0 and time t, one finds that there is an infinite class of symmetries in Lagrange label space that map onto each Eulerian Lie point symmetry of the Galilei group. The allowed transformation of the Lagrangian fluid labels x 0 corresponds to a fluid relabelling symmetry, including the case where there is no change in the fluid labels. We also consider a class of three, well-known, scaling symmetries for a gas with a constant adiabatic index γ. These symmetries map onto a modified form of the fluid relabelling symmetry determining equations, with non-zero source terms. We determine under which conditions these symmetries are variational or divergence symmetries of the action, and determine the corresponding Lagrangian and Eulerian conservation laws by use of Noether's theorem. These conservation laws depend on the initial entropy, density and magnetic field of the fluid. We derive the conservation law corresponding to the projective symmetry in gas dynamics, for the case γ = (n + 2)/n, where n is the number of Cartesian space coordinates, and the corresponding result for two-dimensional (2D) MHD, for the case γ = 2. Lie algebraic structures in Lagrange label space corresponding to the symmetries are investigated. The Lie algebraic symmetry relations between the fluid relabelling symmetries in Lagrange label space, and their commutators with a linear combination of the three symmetries with a constant adiabatic index are delineated

The master symmetry and time dependent symmetries of the differential–difference KP equation

International Nuclear Information System (INIS)

Khanizadeh, Farbod

2014-01-01

We first obtain the master symmetry of the differential–difference KP equation. Then we show how this master symmetry, through sl(2,C)-representation of the equation, can construct generators of time dependent symmetries. (paper)

Symmetries of Chimera States

Science.gov (United States)

Kemeth, Felix P.; Haugland, Sindre W.; Krischer, Katharina

2018-05-01

Symmetry broken states arise naturally in oscillatory networks. In this Letter, we investigate chaotic attractors in an ensemble of four mean-coupled Stuart-Landau oscillators with two oscillators being synchronized. We report that these states with partially broken symmetry, so-called chimera states, have different setwise symmetries in the incoherent oscillators, and in particular, some are and some are not invariant under a permutation symmetry on average. This allows for a classification of different chimera states in small networks. We conclude our report with a discussion of related states in spatially extended systems, which seem to inherit the symmetry properties of their counterparts in small networks.

Seismic transmission operator reciprocity - II: impedance-operator symmetry via elastic lateral modes

Science.gov (United States)

Thomson, C. J.

2015-08-01

The properties of the overburden transmission response are of particular interest for the analysis of reflectivity illumination or blurring in seismic depth imaging. The first step to showing a transmission-operator reciprocity property is to identify the symmetry of the so-called displacement-to-traction operators. The latter are analogous to Dirichlet-to-Neumann operators and they may also be called impedance operators. Their symmetry is deduced here after development of a formal spectral or modal theory of lateral wavefunctions in a laterally heterogeneous generally anisotropic elastic medium. The elastic lateral modes are displacement-traction 6-vectors and they are built from two auxiliary 3-vector lateral-mode bases. These auxiliary modes arise from Hermitian and anti-Hermitian operators, so they have familiar properties such as orthogonality. There is no assumption of down/up symmetry of the elasticity tensor, but basic assumptions are made about the existence and completeness of the elastic modes. A point-symmetry property appears and plays a central role. The 6-vector elastic modes have a symplectic orthogonality property, which facilitates the development of modal expansions for 6-vector functions of the lateral coordinates when completeness is assumed. While the elastic modal theory is consistent with the laterally homogeneous case, numerical work would provide confidence that it is correct in general. An appendix contains an introductory overview of acoustic lateral modes that were studied by other authors, given from the perspective of this new work. A distinction is drawn between unit normalization of scalar auxiliary modes and a separate energy-flux normalization of 2-vector acoustic modes. Neither is crucial to the form of acoustic pressure-to-velocity or impedance operators. This statement carries over to the elastic case for the 3-vector auxiliary- and 6-vector elastic-mode normalizations. The modal theory is used to construct the kernel of the

Dihedral flavor symmetries

Energy Technology Data Exchange (ETDEWEB)

Blum, Alexander Simon

2009-06-10

This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D{sub 4}, the other describing quarks and employing the symmetry D{sub 14}. In the latter model it is the quark mixing matrix element V{sub ud} - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)

Dihedral flavor symmetries

International Nuclear Information System (INIS)

Blum, Alexander Simon

2009-01-01

This thesis deals with the possibility of describing the flavor sector of the Standard Model of Particle Physics (with neutrino masses), that is the fermion masses and mixing matrices, with a discrete, non-abelian flavor symmetry. In particular, mass independent textures are considered, where one or several of the mixing angles are determined by group theory alone and are independent of the fermion masses. To this end a systematic analysis of a large class of discrete symmetries, the dihedral groups, is analyzed. Mass independent textures originating from such symmetries are described and it is shown that such structures arise naturally from the minimization of scalar potentials, where the scalars are gauge singlet flavons transforming non-trivially only under the flavor group. Two models are constructed from this input, one describing leptons, based on the group D 4 , the other describing quarks and employing the symmetry D 14 . In the latter model it is the quark mixing matrix element V ud - basically the Cabibbo angle - which is at leading order predicted from group theory. Finally, discrete flavor groups are discussed as subgroups of a continuous gauge symmetry and it is shown that this implies that the original gauge symmetry is broken by fairly large representations. (orig.)

PT symmetry breaking in non-central potentials

International Nuclear Information System (INIS)

Levai, G.

2007-01-01

Complete text of publication follows. PT-symmetric systems represent a special example for non-hermitian problems in quantum mechanics. The Hamiltonian of these systems is invariant under the simultaneous action of the P space and T time inversion operations. They resemble hermitian problems in that they typically possess real energy spectrum. However, increasing non-hermiticity, e.g. the imaginary potential component the real energy eigenvalues merge pairwise and turn into complex conjugate pairs and at the same time, the energy eigenstates cease to be eigenstates of the PT operator. The mechanism of this spontaneous breakdown of PT symmetry has been investigated in one spatial dimension, and our aim was to extend these studies to higher dimensions. Assuming that the solutions of the Schroedinger equation -Δψ(r) + V (r)ψ(r) = Eψ(r) can be obtained by the separation of the radial and angular variables, we substitute ψ(r,θ,φ) = r -1 φ(r) sin -1/2 ω(θ)τ(ψ) in (4), where r [0,∞), θ [0,π] and ψ [0,2π]. Further, we assume that the angular components of the wave function satisfy ω' = (P(θ) - p)ω, τ' = (K(ψ) - k)τ, where τ(ψ) has to be defined with periodic boundary conditions. Then the complete three-dimensional problem becomes solvable if the non-central potential takes the form V(r,θ,ψ) = V 0 (r)+ K(ψ)/r 2 sin 2 θ + P(θ)/r 2 - k-1/4/r 2 sin 2 θ. Here V 0 (r) is a central potential appearing in -φ'+[V 0 (r) + 1/r 2 (p - 1/4] φ - Eφ = 0. Note that is formally identical with a conventional radial Schroedinger equation complete with a centrifugal term. In order to solve properly, the state dependence of has to be eliminated, i.e. its dependence on k has to be cancelled by combining the last two terms. This effectively means that has to be solved with a potential P(θ) that contains a sin -2 θ type term. Next we investigate under which conditions the non-central potential exhibits PT symmetry. It is seen that space reflection P : r → -r

Weak C* Hopf Symmetry

OpenAIRE

Rehren, K. -H.

1996-01-01

Weak C* Hopf algebras can act as global symmetries in low-dimensional quantum field theories, when braid group statistics prevents group symmetries. Possibilities to construct field algebras with weak C* Hopf symmetry from a given theory of local observables are discussed.

Intrinsic membrane properties causing a bistable behaviour of α-motoneurones

DEFF Research Database (Denmark)

Hounsgaard, J.; Hultborn, H.; Jespersen, B.

1984-01-01

injected depolarizing current pulse and is terminated by a short train of inhibitory synaptic potentials or a hyperpolarizing current pulse. It is concluded that maintained motor unit firing triggered by a brief train of impulses in Ia afferent reflects an intrinsic bistable behaviour of α-motoneurones....

Intrinsic motivation as a predictor of work outcome after vocational rehabilitation in schizophrenia.

Science.gov (United States)

Saperstein, Alice M; Fiszdon, Joanna M; Bell, Morris D

2011-09-01

Intrinsic motivation is a construct commonly used in explaining goal-directed behavior. In people with schizophrenia, intrinsic motivation is usually subsumed as a feature of negative symptoms or underlying neurocognitive dysfunction. A growing literature reflects an interest in defining and measuring motivational impairment in schizophrenia and in delineating the specific role of intrinsic motivation as both an independent predictor and a mediator of psychosocial functioning. This cross-sectional study examined intrinsic motivation as a predictor of vocational outcomes for 145 individuals with schizophrenia and schizoaffective disorder participating in a 6-month work rehabilitation trial. Correlation and mediation analyses examined baseline intrinsic motivation and negative symptoms in relation to work hours and work performance. Data support a significant relationship between intrinsic motivation and negative symptoms and significant correlations with outcome variables, such that lower negative symptoms and greater intrinsic motivation were associated with better work functioning. Moreover, in this sample, intrinsic motivation fully mediated the relationships between negative symptoms, work productivity, and work performance. These results have significant implications on the design of work rehabilitation interventions for people with schizophrenia and support a role for targeting intrinsic motivation directly to influence vocational functioning. Future directions for research and intervention are discussed.

The near-symmetry of proteins.

Science.gov (United States)

Bonjack-Shterengartz, Maayan; Avnir, David

2015-04-01

The majority of protein oligomers form clusters which are nearly symmetric. Understanding of that imperfection, its origins, and perhaps also its advantages requires the conversion of the currently used vague qualitative descriptive language of the near-symmetry into an accurate quantitative measure that will allow to answer questions such as: "What is the degree of symmetry deviation of the protein?," "how do these deviations compare within a family of proteins?," and so on. We developed quantitative methods to answer this type of questions, which are capable of analyzing the whole protein, its backbone or selected portions of it, down to comparison of symmetry-related specific amino-acids, and which are capable of visualizing the various levels of symmetry deviations in the form of symmetry maps. We have applied these methods on an extensive list of homomers and heteromers and found that apparently all proteins never reach perfect symmetry. Strikingly, even homomeric protein clusters are never ideally symmetric. We also found that the main burden of symmetry distortion is on the amino-acids near the symmetry axis; that it is mainly the more hydrophilic amino-acids that take place in symmetry-distortive interactions; and more. The remarkable ability of heteromers to preserve near-symmetry, despite the different sequences, was also shown and analyzed. The comprehensive literature on the suggested advantages symmetric oligomerizations raises a yet-unsolved key question: If symmetry is so advantageous, why do proteins stop shy of perfect symmetry? Some tentative answers to be tested in further studies are suggested in a concluding outlook. © 2014 Wiley Periodicals, Inc.

Approximate reflection coefficients for a thin VTI layer

KAUST Repository

Hao, Qi; Stovas, Alexey

2017-01-01

We present an approximate method to derive simple expressions for the reflection coefficients of P- and SV-waves for a thin transversely isotropic layer with a vertical symmetry axis (VTI) embedded in a homogeneous VTI background. The layer

Symmetry in Social Construction during ERP Implementation: A Systems Security Perspective

Directory of Open Access Journals (Sweden)

Kennedy Njenga

2014-03-01

Full Text Available The principle of symmetry in enterprise resource planning (ERP systems implementation holds that the researcher should deploy impartial explanation in cases of success as in cases of failure. This article examines the symmetry intrinsic in social construction within the various stages of the ERP development life cycle, from initiation to implementation. Discourse on symmetry focuses on whether social constructs are able to influence ERP implementation positively (success or negatively (failure and whether this exposes ERP systems to information security risk. The theoretical lens of social construction of technology (SCOT theory, a theory premised on social interaction between agents and technology artefacts, is applied for this purpose. The research was quantitative with a survey having been conducted on information technology (IT and information security (IS practitioners. Results of the study highlight the significant role social construction plays because of the direct linkage it has with the implementation of information security controls in ERP systems.  The research delineated five social constructs, namely positional influence, reward influence, coercive influence, expert influence and referent influence. For purposes of this research and on the sampling criteria applied, the construct ‘expert influence’, a typology of social construction, is shown to be more domineering than other typologies of social construction and is seen as providing symmetrical balance between governing ERP security (success and risk (failure. Implications of these results for theory and practice are discussed in the main article.

The role of symmetry in the theory of inelastic high-energy electron scattering and its application to atomic-resolution core-loss imaging.

Science.gov (United States)

Dwyer, C

2015-04-01

The inelastic scattering of a high-energy electron in a solid constitutes a bipartite quantum system with an intrinsically large number of excitations, posing a considerable challenge for theorists. It is demonstrated how and why the utilization of symmetries, or approximate symmetries, can lead to significant improvements in both the description of the scattering physics and the efficiency of numerical computations. These ideas are explored thoroughly for the case of core-loss excitations, where it is shown that the coupled angular momentum basis leads to dramatic improvements over the bases employed in previous work. The resulting gains in efficiency are demonstrated explicitly for K-, L- and M-shell excitations, including such excitations in the context of atomic-resolution imaging in the scanning transmission electron microscope. The utilization of other symmetries is also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides

KAUST Repository

Moody, Galan; Kavir Dass, Chandriker; Hao, Kai; Chen, Chang-Hsiao; Li, Lain-Jong; Singh, Akshay; Tran, Kha; Clark, Genevieve; Xu, Xiaodong; Berghä user, Gunnar; Malic, Ermin; Knorr, Andreas; Li, Xiaoqin

2015-01-01

unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines

Quandles and topological pairs symmetry, knots, and cohomology

CERN Document Server

Nosaka, Takefumi

2017-01-01

This book surveys quandle theory, starting from basic motivations and going on to introduce recent developments of quandles with topological applications and related topics. The book is written from topological aspects, but it illustrates how esteemed quandle theory is in mathematics, and it constitutes a crash course for studying quandles. More precisely, this work emphasizes the fresh perspective that quandle theory can be useful for the study of low-dimensional topology (e.g., knot theory) and relative objects with symmetry. The direction of research is summarized as “We shall thoroughly (re)interpret the previous studies of relative symmetry in terms of the quandle”. The perspectives contained herein can be summarized by the following topics. The first is on relative objects G/H, where G and H are groups, e.g., polyhedrons, reflection, and symmetric spaces. Next, central extensions of groups are discussed, e.g., spin structures, K2 groups, and some geometric anomalies. The third topic is a method to s...

Approximate and renormgroup symmetries

International Nuclear Information System (INIS)

Ibragimov, Nail H.; Kovalev, Vladimir F.

2009-01-01

''Approximate and Renormgroup Symmetries'' deals with approximate transformation groups, symmetries of integro-differential equations and renormgroup symmetries. It includes a concise and self-contained introduction to basic concepts and methods of Lie group analysis, and provides an easy-to-follow introduction to the theory of approximate transformation groups and symmetries of integro-differential equations. The book is designed for specialists in nonlinear physics - mathematicians and non-mathematicians - interested in methods of applied group analysis for investigating nonlinear problems in physical science and engineering. (orig.)

Symmetry, asymmetry and dissymmetry

International Nuclear Information System (INIS)

Wackenheim, A.; Zollner, G.

1987-01-01

The authors discuss the concept of symmetry and defect of symmetry in radiological imaging and recall the definition of asymmetry (congenital or constitutional) and dissymmetry (acquired). They then describe a rule designed for the cognitive method of automatic evaluation of shape recognition data and propose the use of reversal symmetry [fr

Translational Symmetry and Microscopic Constraints on Symmetry-Enriched Topological Phases: A View from the Surface

Directory of Open Access Journals (Sweden)

Meng Cheng

2016-12-01

Full Text Available The Lieb-Schultz-Mattis theorem and its higher-dimensional generalizations by Oshikawa and Hastings require that translationally invariant 2D spin systems with a half-integer spin per unit cell must either have a continuum of low energy excitations, spontaneously break some symmetries, or exhibit topological order with anyonic excitations. We establish a connection between these constraints and a remarkably similar set of constraints at the surface of a 3D interacting topological insulator. This, combined with recent work on symmetry-enriched topological phases with on-site unitary symmetries, enables us to develop a framework for understanding the structure of symmetry-enriched topological phases with both translational and on-site unitary symmetries, including the effective theory of symmetry defects. This framework places stringent constraints on the possible types of symmetry fractionalization that can occur in 2D systems whose unit cell contains fractional spin, fractional charge, or a projective representation of the symmetry group. As a concrete application, we determine when a topological phase must possess a “spinon” excitation, even in cases when spin rotational invariance is broken down to a discrete subgroup by the crystal structure. We also describe the phenomena of “anyonic spin-orbit coupling,” which may arise from the interplay of translational and on-site symmetries. These include the possibility of on-site symmetry defect branch lines carrying topological charge per unit length and lattice dislocations inducing degeneracies protected by on-site symmetry.

Approximate and renormgroup symmetries

Energy Technology Data Exchange (ETDEWEB)

Ibragimov, Nail H. [Blekinge Institute of Technology, Karlskrona (Sweden). Dept. of Mathematics Science; Kovalev, Vladimir F. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Mathematical Modeling

2009-07-01

''Approximate and Renormgroup Symmetries'' deals with approximate transformation groups, symmetries of integro-differential equations and renormgroup symmetries. It includes a concise and self-contained introduction to basic concepts and methods of Lie group analysis, and provides an easy-to-follow introduction to the theory of approximate transformation groups and symmetries of integro-differential equations. The book is designed for specialists in nonlinear physics - mathematicians and non-mathematicians - interested in methods of applied group analysis for investigating nonlinear problems in physical science and engineering. (orig.)

Quantum symmetry in quantum theory

International Nuclear Information System (INIS)

Schomerus, V.

1993-02-01

Symmetry concepts have always been of great importance for physical problems like explicit calculations, classification or model building. More recently, new 'quantum symmetries' ((quasi) quantum groups) attracted much interest in quantum theory. It is shown that all these quantum symmetries permit a conventional formulation as symmetry in quantum mechanics. Symmetry transformations can act on the Hilbert space H of physical states such that the ground state is invariant and field operators transform covariantly. Models show that one must allow for 'truncation' in the tensor product of representations of a quantum symmetry. This means that the dimension of the tensor product of two representations of dimension σ 1 and σ 2 may be strictly smaller than σ 1 σ 2 . Consistency of the transformation law of field operators local braid relations leads us to expect, that (weak) quasi quantum groups are the most general symmetries in local quantum theory. The elements of the R-matrix which appears in these local braid relations turn out to be operators on H in general. It will be explained in detail how examples of field algebras with weak quasi quantum group symmetry can be obtained. Given a set of observable field with a finite number of superselection sectors, a quantum symmetry together with a complete set of covariant field operators which obey local braid relations are constructed. A covariant transformation law for adjoint fields is not automatic but will follow when the existence of an appropriate antipode is assumed. At the example of the chiral critical Ising model, non-uniqueness of the quantum symmetry will be demonstrated. Generalized quantum symmetries yield examples of gauge symmetries in non-commutative geometry. Quasi-quantum planes are introduced as the simplest examples of quasi-associative differential geometry. (Weak) quasi quantum groups can act on them by generalized derivations much as quantum groups do in non-commutative (differential-) geometry

Symmetry Motion Classes; Cambridge Conference on School Mathematics Feasibility Study No. 40.

Science.gov (United States)

McLane, Lyn

These materials were written with the aim of reflecting the thinking of The Cambridge Conference on School Mathematics (CCSM) regarding the goals and objectives for school mathematics. This document details the planning and response for each of ten lessons involving symmetry motions. The problems focused on (1) combining motions in a given order,…

Leptogenesis and residual CP symmetry

International Nuclear Information System (INIS)

Chen, Peng; Ding, Gui-Jun; King, Stephen F.

2016-01-01

We discuss flavour dependent leptogenesis in the framework of lepton flavour models based on discrete flavour and CP symmetries applied to the type-I seesaw model. Working in the flavour basis, we analyse the case of two general residual CP symmetries in the neutrino sector, which corresponds to all possible semi-direct models based on a preserved Z 2 in the neutrino sector, together with a CP symmetry, which constrains the PMNS matrix up to a single free parameter which may be fixed by the reactor angle. We systematically study and classify this case for all possible residual CP symmetries, and show that the R-matrix is tightly constrained up to a single free parameter, with only certain forms being consistent with successful leptogenesis, leading to possible connections between leptogenesis and PMNS parameters. The formalism is completely general in the sense that the two residual CP symmetries could result from any high energy discrete flavour theory which respects any CP symmetry. As a simple example, we apply the formalism to a high energy S 4 flavour symmetry with a generalized CP symmetry, broken to two residual CP symmetries in the neutrino sector, recovering familiar results for PMNS predictions, together with new results for flavour dependent leptogenesis.

Symmetry methods for option pricing

Science.gov (United States)

Davison, A. H.; Mamba, S.

2017-06-01

We obtain a solution of the Black-Scholes equation with a non-smooth boundary condition using symmetry methods. The Black-Scholes equation along with its boundary condition are first transformed into the one dimensional heat equation and an initial condition respectively. We then find an appropriate general symmetry generator of the heat equation using symmetries and the fundamental solution of the heat equation. The symmetry generator is chosen such that the boundary condition is left invariant; the symmetry can be used to solve the heat equation and hence the Black-Scholes equation.

Algorithm for research of mathematical physics equations symmetries. Symmetries of the free Schroedinger equation

International Nuclear Information System (INIS)

Kotel'nikov, G.A.

1994-01-01

An algorithm id proposed for research the symmetries of mathematical physics equation. The application of this algorithm to the Schroedinger equation permitted to establish, that in addition to the known symmetry the Schroedinger equation possesses also the relativistic symmetry

Hyperbolic-symmetry vector fields.

Science.gov (United States)

Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

2015-12-14

We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.

Relativistic U(3) symmetry and pseudo-U(3) symmetry of the Dirac Hamiltonian

International Nuclear Information System (INIS)

Ginocchio, Joseph N.

2010-01-01

The Dirac Hamiltonian with relativistic scalar and vector harmonic oscillator potentials has been solved analytically in two limits. One is the spin limit for which spin is an invariant symmetry of the the Dirac Hamiltonian and the other is the pseudo-spin limit for which pseudo-spin is an invariant symmetry of the Dirac Hamiltonian. The spin limit occurs when the scalar potential is equal to the vector potential plus a constant, and the pseudospin limit occurs when the scalar potential is equal in magnitude but opposite in sign to the vector potential plus a constant. Like the non-relativistic harmonic oscillator, each of these limits has a higher symmetry. For example, for the spherically symmetric oscillator, these limits have a U(3) and pseudo-U(3) symmetry respectively. We shall discuss the eigenfunctions and eigenvalues of these two limits and derive the relativistic generators for the U(3) and pseudo-U(3) symmetry. We also argue, that, if an anti-nucleon can be bound in a nucleus, the spectrum will have approximate spin and U(3) symmetry.

Is space-time symmetry a suitable generalization of parity-time symmetry?

International Nuclear Information System (INIS)

Amore, Paolo; Fernández, Francisco M.; Garcia, Javier

2014-01-01

We discuss space-time symmetric Hamiltonian operators of the form H=H 0 +igH ′ , where H 0 is Hermitian and g real. H 0 is invariant under the unitary operations of a point group G while H ′ is invariant under transformation by elements of a subgroup G ′ of G. If G exhibits irreducible representations of dimension greater than unity, then it is possible that H has complex eigenvalues for sufficiently small nonzero values of g. In the particular case that H is parity-time symmetric then it appears to exhibit real eigenvalues for all 0symmetry and perturbation theory enable one to predict whether H may exhibit real or complex eigenvalues for g>0. We illustrate the main theoretical results and conclusions of this paper by means of two- and three-dimensional Hamiltonians exhibiting a variety of different point-group symmetries. - Highlights: • Space-time symmetry is a generalization of PT symmetry. • The eigenvalues of a space-time Hamiltonian are either real or appear as pairs of complex conjugate numbers. • In some cases all the eigenvalues are real for some values of a potential-strength parameter g. • At some value of g space-time symmetry is broken and complex eigenvalues appear. • Some multidimensional oscillators exhibit broken space-time symmetry for all values of g

Symmetry Festival 2016

CERN Document Server

2016-01-01

The Symmetry Festival is a science and art program series, the most important periodic event (see its history) to bring together scientists, artists, educators and practitioners interested in symmetry (its roots, what is behind, applications, etc.), or in the consequences of its absence.

Intrinsic Scene Decomposition from RGB-D Images

KAUST Repository

Hachama, Mohammed; Ghanem, Bernard; Wonka, Peter

2015-01-01

In this paper, we address the problem of computing an intrinsic decomposition of the colors of a surface into an albedo and a shading term. The surface is reconstructed from a single or multiple RGB-D images of a static scene obtained from different views. We thereby extend and improve existing works in the area of intrinsic image decomposition. In a variational framework, we formulate the problem as a minimization of an energy composed of two terms: a data term and a regularity term. The first term is related to the image formation process and expresses the relation between the albedo, the surface normals, and the incident illumination. We use an affine shading model, a combination of a Lambertian model, and an ambient lighting term. This model is relevant for Lambertian surfaces. When available, multiple views can be used to handle view-dependent non-Lambertian reflections. The second term contains an efficient combination of l2 and l1-regularizers on the illumination vector field and albedo respectively. Unlike most previous approaches, especially Retinex-like techniques, these terms do not depend on the image gradient or texture, thus reducing the mixing shading/reflectance artifacts and leading to better results. The obtained non-linear optimization problem is efficiently solved using a cyclic block coordinate descent algorithm. Our method outperforms a range of state-of-the-art algorithms on a popular benchmark dataset.

Intrinsic Scene Decomposition from RGB-D Images

KAUST Repository

Hachama, Mohammed

2015-12-07

In this paper, we address the problem of computing an intrinsic decomposition of the colors of a surface into an albedo and a shading term. The surface is reconstructed from a single or multiple RGB-D images of a static scene obtained from different views. We thereby extend and improve existing works in the area of intrinsic image decomposition. In a variational framework, we formulate the problem as a minimization of an energy composed of two terms: a data term and a regularity term. The first term is related to the image formation process and expresses the relation between the albedo, the surface normals, and the incident illumination. We use an affine shading model, a combination of a Lambertian model, and an ambient lighting term. This model is relevant for Lambertian surfaces. When available, multiple views can be used to handle view-dependent non-Lambertian reflections. The second term contains an efficient combination of l2 and l1-regularizers on the illumination vector field and albedo respectively. Unlike most previous approaches, especially Retinex-like techniques, these terms do not depend on the image gradient or texture, thus reducing the mixing shading/reflectance artifacts and leading to better results. The obtained non-linear optimization problem is efficiently solved using a cyclic block coordinate descent algorithm. Our method outperforms a range of state-of-the-art algorithms on a popular benchmark dataset.

Unified Symmetry of Hamilton Systems

International Nuclear Information System (INIS)

Xu Xuejun; Qin Maochang; Mei Fengxiang

2005-01-01

The definition and the criterion of a unified symmetry for a Hamilton system are presented. The sufficient condition under which the Noether symmetry is a unified symmetry for the system is given. A new conserved quantity, as well as the Noether conserved quantity and the Hojman conserved quantity, deduced from the unified symmetry, is obtained. An example is finally given to illustrate the application of the results.

Intrinsic magnetic torque at low magnetic induction

International Nuclear Information System (INIS)

Doria, M.M.; Oliveira, I.G. de.

1993-01-01

Using anisotropic London theory the intrinsic magnetic torque for extreme type II uniaxial superconductors for any value of the magnetic induction is obtained. It is considered the vortex lines straight and take into account the contribution of the supercurrents flowing inside the vortex core within the London theory. It is shown that the interline and intra line free energies give opposite torque contributions, the first drives the magnetic induction parallel to the superconductor's axis of symmetry and the second orthogonal to it. At high magnetic induction torque expression obtained generalizes V. Kogan's formula since it has no free parameters other than the anisotropy γ = m 1 /m 3 and the Ginzburg-Landau parameter κ. At low magnetic induction it is proposed a way to observe vortex chains effects in the total torque based on the fact that London theory is linear and the energy to make a single vortex line in space is independent of the magnetic induction. (author)

Symmetry of crystals and molecules

CERN Document Server

Ladd, Mark

2014-01-01

This book successfully combines a thorough treatment of molecular and crystalline symmetry with a simple and informal writing style. By means of familiar examples the author helps to provide the reader with those conceptual tools necessary for the development of a clear understanding of what are often regarded as 'difficult' topics. Christopher Hammond, University of Leeds This book should tell you everything you need to know about crystal and molecular symmetry. Ladd adopts an integrated approach so that the relationships between crystal symmetry, molecular symmetry and features of chemical interest are maintained and reinforced. The theoretical aspects of bonding and symmetry are also well represented, as are symmetry-dependent physical properties and the applications of group theory. The comprehensive coverage will make this book a valuable resource for a broad range of readers.

Intrinsic rippling enhances static non-reciprocity in a graphene metamaterial.

Science.gov (United States)

Ho, Duc Tam; Park, Harold S; Kim, Sung Youb

2018-01-18

In mechanical systems, Maxwell-Betti reciprocity means that the displacement at point B in response to a force at point A is the same as the displacement at point A in response to the same force applied at point B. Because the notion of reciprocity is general, fundamental, and is operant for other physical systems like electromagnetics, acoustics, and optics, there is significant interest in understanding systems that are not reciprocal, or exhibit non-reciprocity. However, most studies on non-reciprocity have occurred in bulk-scale structures for dynamic problems involving time reversal symmetry. As a result, little is known about the mechanisms governing static non-reciprocal responses, particularly in atomically-thin two-dimensional materials like graphene. Here, we use classical atomistic simulations to demonstrate that out-of-plane ripples, which are intrinsic to graphene, enable significant, multiple orders of magnitude enhancements in the statically non-reciprocal response of graphene metamaterials. Specifically, we find that a striking interplay between the ripples and the stress fields that are induced in the metamaterials due to their geometry impacts the displacements that are transmitted by the metamaterial, thus leading to a significantly enhanced static non-reciprocal response. This study thus demonstrates the potential of two-dimensional mechanical metamaterials for symmetry-breaking applications.

Physics from symmetry

CERN Document Server

Schwichtenberg, Jakob

2015-01-01

This is a textbook that derives the fundamental theories of physics from symmetry.   It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations.

Hidden gauge symmetry

International Nuclear Information System (INIS)

O'Raifeartaigh, L.

1979-01-01

This review describes the principles of hidden gauge symmetry and of its application to the fundamental interactions. The emphasis is on the structure of the theory rather than on the technical details and, in order to emphasise the structure, gauge symmetry and hidden symmetry are first treated as independent phenomena before being combined into a single (hidden gauge symmetric) theory. The main application of the theory is to the weak and electromagnetic interactions of the elementary particles, and although models are used for comparison with experiment and for illustration, emphasis is placed on those features of the application which are model-independent. (author)

A model capturing novel strand symmetries in bacterial DNA

International Nuclear Information System (INIS)

Sobottka, Marcelo; Hart, Andrew G.

2011-01-01

Highlights: → We propose a simple stochastic model to construct primitive DNA sequences. → The model provide an explanation for Chargaff's second parity rule in primitive DNA sequences. → The model is also used to predict a novel type of strand symmetry in primitive DNA sequences. → We extend the results for bacterial DNA sequences and compare distributional properties intrinsic to the model to statistical estimates from 1049 bacterial genomes. → We find out statistical evidences that the novel type of strand symmetry holds for bacterial DNA sequences. -- Abstract: Chargaff's second parity rule for short oligonucleotides states that the frequency of any short nucleotide sequence on a strand is approximately equal to the frequency of its reverse complement on the same strand. Recent studies have shown that, with the exception of organellar DNA, this parity rule generally holds for double-stranded DNA genomes and fails to hold for single-stranded genomes. While Chargaff's first parity rule is fully explained by the Watson-Crick pairing in the DNA double helix, a definitive explanation for the second parity rule has not yet been determined. In this work, we propose a model based on a hidden Markov process for approximating the distributional structure of primitive DNA sequences. Then, we use the model to provide another possible theoretical explanation for Chargaff's second parity rule, and to predict novel distributional aspects of bacterial DNA sequences.

Symmetry associated with symmetry break: Revisiting ants and humans escaping from multiple-exit rooms

Science.gov (United States)

Ji, Q.; Xin, C.; Tang, S. X.; Huang, J. P.

2018-02-01

Crowd panic has incurred massive injuries or deaths throughout the world, and thus understanding it is particularly important. It is now a common knowledge that crowd panic induces "symmetry break" in which some exits are jammed while others are underutilized. Amazingly, here we show, by experiment, simulation and theory, that a class of symmetry patterns come to appear for ants and humans escaping from multiple-exit rooms while the symmetry break exists. Our symmetry pattern is described by the fact that the ratio between the ensemble-averaging numbers of ants or humans escaping from different exits is equal to the ratio between the widths of the exits. The mechanism lies in the effect of heterogeneous preferences of agents with limited information for achieving the Nash equilibrium. This work offers new insights into how to improve public safety because large public areas are always equipped with multiple exits, and it also brings an ensemble-averaging method for seeking symmetry associated with symmetry breaking.

Particle-hole symmetry for composite fermions: An emergent symmetry in the fractional quantum Hall effect

DEFF Research Database (Denmark)

Coimbatore Balram, Ajit; Jain, Jainendra

2017-01-01

The particle-hole (PH) symmetry of {\\em electrons} is an exact symmetry of the electronic Hamiltonian confined to a specific Landau level, and its interplay with the formation of composite fermions has attracted much attention of late. This article investigates an emergent symmetry...... in the fractional quantum Hall effect, namely the PH symmetry of {\\em composite fermions}, which relates states at composite fermion filling factors $\

Classical mirror symmetry

CERN Document Server

Jinzenji, Masao

2018-01-01

This book furnishes a brief introduction to classical mirror symmetry, a term that denotes the process of computing Gromov–Witten invariants of a Calabi–Yau threefold by using the Picard–Fuchs differential equation of period integrals of its mirror Calabi–Yau threefold. The book concentrates on the best-known example, the quintic hypersurface in 4-dimensional projective space, and its mirror manifold. First, there is a brief review of the process of discovery of mirror symmetry and the striking result proposed in the celebrated paper by Candelas and his collaborators. Next, some elementary results of complex manifolds and Chern classes needed for study of mirror symmetry are explained. Then the topological sigma models, the A-model and the B-model, are introduced. The classical mirror symmetry hypothesis is explained as the equivalence between the correlation function of the A-model of a quintic hyper-surface and that of the B-model of its mirror manifold. On the B-model side, the process of construct...

In search of symmetry lost

CERN Multimedia

Wilczek, Frank

2004-01-01

Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world (8 pages) Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world. The discrepancy is ascribed to a pervasive symmetry-breaking field, which fills all space uniformly, rendering the Universe a sort of exotic superconductor. So far, the evidence for these bold ideas is indirect. But soon the theory will undergo a critical test depending on whether the quanta of this symmetry-breaking field, the so-called Higgs particles, are produced at the Large Hadron Collider (due to begin operation in 2007).

Charge symmetry at the partonic level

Energy Technology Data Exchange (ETDEWEB)

Londergan, J. T.; Peng, J. C.; Thomas, A. W.

2010-07-01

This review article discusses the experimental and theoretical status of partonic charge symmetry. It is shown how the partonic content of various structure functions gets redefined when the assumption of charge symmetry is relaxed. We review various theoretical and phenomenological models for charge symmetry violation in parton distribution functions. We summarize the current experimental upper limits on charge symmetry violation in parton distributions. A series of experiments are presented, which might reveal partonic charge symmetry violation, or alternatively might lower the current upper limits on parton charge symmetry violation.

Symmetry and topology in evolution

International Nuclear Information System (INIS)

Lukacs, B.; Berczi, S.; Molnar, I.; Paal, G.

1991-10-01

This volume contains papers of an interdisciplinary symposium on evolution. The aim of this symposium, held in Budapest, Hungary, 28-29 May 1991, was to clear the role of symmetry and topology at different levels of the evolutionary processes. 21 papers were presented, their topics included evolution of the Universe, symmetry of elementary particles, asymmetry of the Earth, symmetry and asymmetry of biomolecules, symmetry and topology of lining objects, human asymmetry etc. (R.P.)

The Symmetry of Multiferroics

OpenAIRE

Harris, A. Brooks

2006-01-01

This paper represents a detailed instruction manual for constructing the Landau expansion for magnetoelectric coupling in incommensurate ferroelectric magnets. The first step is to describe the magnetic ordering in terms of symmetry adapted coordinates which serve as complex valued magnetic order parameters whose transformation properties are displayed. In so doing we use the previously proposed technique to exploit inversion symmetry, since this symmetry had been universally overlooked. Havi...

Symmetry and Interculturality

Science.gov (United States)

Marchis, Iuliana

2009-01-01

Symmetry is one of the fundamental concepts in Geometry. It is a Mathematical concept, which can be very well connected with Art and Ethnography. The aim of the article is to show how to link the geometrical concept symmetry with interculturality. For this mosaics from different countries are used.

Dynamical symmetries for fermions

International Nuclear Information System (INIS)

Guidry, M.

1989-01-01

An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E 2 ) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and ''exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs

Symmetry inheritance of scalar fields

International Nuclear Information System (INIS)

Ivica Smolić

2015-01-01

Matter fields do not necessarily have to share the symmetries with the spacetime they live in. When this happens, we speak of the symmetry inheritance of fields. In this paper we classify the obstructions of symmetry inheritance by the scalar fields, both real and complex, and look more closely at the special cases of stationary and axially symmetric spacetimes. Since the symmetry noninheritance is present in the scalar fields of boson stars and may enable the existence of the black hole scalar hair, our results narrow the possible classes of such solutions. Finally, we define and analyse the symmetry noninheritance contributions to the Komar mass and angular momentum of the black hole scalar hair. (paper)

Spontaneous emergence of gauge symmetry

International Nuclear Information System (INIS)

Nielsen, H.B.; Brene, N.

1987-05-01

Within the framework of the random dynamics project we have demonstrated several mechanisms for breakdown of a preexisting exact gauge symmetry. This note concerns and reviews a mechanism which works essentially in the opposite direction, leading from am accidental approximate symmetry to an exact formal gauge symmetry. It was shown that although this symmetry is a priori only strictly formal, it can under certain circumstances lead to a physical consequence: the corresponding gauge boson becomes massless. In the chaotic models typical for our random dynamics project there is, of course, a strong competition between this mechanism and mechanisms which temd to destroy the symmetry and give mass(es) to the gauge boson(s). (orig.)

Quantum symmetries in particle interactions

International Nuclear Information System (INIS)

Shirkov, D.V.

1983-01-01

The concept of a quantum symmetry is introduced as a symmetry in the formulation of which quantum representations and specific quantum notions are used essentially. Three quantum symmetry principles are discussed: the principle of renormalizability (possibly super-renormalizability), the principle of local gauge symmetry, and the principle of supersymmetry. It is shown that these principles play a deterministic role in the development of quantum field theory. Historically their use has led to ever stronger restrictions on the interaction mechanism of quantum fields

Gauge symmetry from decoupling

Directory of Open Access Journals (Sweden)

C. Wetterich

2017-02-01

Full Text Available Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang–Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.

Symmetry and group theory in chemistry

CERN Document Server

Ladd, M

1998-01-01

A comprehensive discussion of group theory in the context of molecular and crystal symmetry, this book covers both point-group and space-group symmetries.Provides a comprehensive discussion of group theory in the context of molecular and crystal symmetryCovers both point-group and space-group symmetriesIncludes tutorial solutions

Killing symmetries in neutron transport

International Nuclear Information System (INIS)

Lukacs, B.; Racz, A.

1992-10-01

Although inside the reactor zone there is no exact continuous spatial symmetry, in certain configurations neutron flux distribution is close to a symmetrical one. In such cases the symmetrical solution could provide a good starting point to determine the non-symmetrical power distribution. All possible symmetries are determined in the 3-dimensional Euclidean space, and the form of the transport equation is discussed in such a coordinate system which is adapted to the particular symmetry. Possible spontaneous symmetry breakings are pointed out. (author) 6 refs

Approximate bilateral symmetry in evaporation-induced polycrystalline structures from droplets of wheat grain leakages and fluctuating asymmetry as quality indicator

Science.gov (United States)

Kokornaczyk, Maria Olga; Dinelli, Giovanni; Betti, Lucietta

2013-01-01

The present paper reports on an observation that dendrite-like polycrystalline structures from evaporating droplets of wheat grain leakages exhibit bilateral symmetry. The exactness of this symmetry, measured by means of fluctuating asymmetry, varies depending on the cultivar and stress factor influence, and seems to correspond to the seed germination rate. In the bodies of plants, animals, and humans, the exactness of bilateral symmetry is known to reflect the environmental conditions of an organism's growth, its health, and its success in sexual selection. In polycrystalline structures, formed under the same conditions, the symmetry exactness depends on the properties of the crystallizing solution such as the composition and viscosity; however, it has never been associated with sample quality. We hypothesize here that, as in living nature, the exactness of approximate bilateral symmetry might be considered a quality indicator also in crystallographic methods applied to food quality analysis.

Symmetry chains and adaptation coefficients

International Nuclear Information System (INIS)

Fritzer, H.P.; Gruber, B.

1985-01-01

Given a symmetry chain of physical significance it becomes necessary to obtain states which transform properly with respect to the symmetries of the chain. In this article we describe a method which permits us to calculate symmetry-adapted quantum states with relative ease. The coefficients for the symmetry-adapted linear combinations are obtained, in numerical form, in terms of the original states of the system and can thus be represented in the form of numerical tables. In addition, one also obtains automatically the matrix elements for the operators of the symmetry groups which are involved, and thus for any physical operator which can be expressed either as an element of the algebra or of the enveloping algebra. The method is well suited for computers once the physically relevant symmetry chain, or chains, have been defined. While the method to be described is generally applicable to any physical system for which semisimple Lie algebras play a role we choose here a familiar example in order to illustrate the method and to illuminate its simplicity. We choose the nuclear shell model for the case of two nucleons with orbital angular momentum l = 1. While the states of the entire shell transform like the smallest spin representation of SO(25) we restrict our attention to its subgroup SU(6) x SU(2)/sub T/. We determine the symmetry chains which lead to total angular momentum SU(2)/sub J/ and obtain the symmetry-adapted states for these chains

An introduction to Yangian symmetries

International Nuclear Information System (INIS)

Bernard, D.

1992-01-01

Some aspects of the quantum Yangians as symmetry algebras of two-dimensional quantum field theories are reviewed. They include two main issues: the first is the classical Heisenberg model, covering non-Abelian symmetries, generators of the symmetries and the semi-classical Yangians, an alternative presentation of the semi-classical Yangians, digression on Poisson-Lie groups. The second is the quantum Heisenberg chain, covering non-Abelian symmetries and the quantum Yangians, the transfer matrix and an alternative presentation of the Yangians, digression on the double Yangians. (K.A.) 15 refs

The conservation of orbital symmetry

CERN Document Server

Woodward, R B

2013-01-01

The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain-or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book ope

Group analysis and renormgroup symmetries

International Nuclear Information System (INIS)

Kovalev, V.F.; Pustovalov, V.V.; Shirkov, D.V.

1996-01-01

An original regular approach to constructing special type symmetries for boundary-value problems, namely renormgroup symmetries, is presented. Different methods of calculating these symmetries based on modern group analysis are described. An application of the approach to boundary value problems is demonstrated with the help of a simple mathematical model. 35 refs

Intrinsic Paramagnetic Meissner Effect Due to s-Wave Odd-Frequency Superconductivity

Directory of Open Access Journals (Sweden)

A. Di Bernardo

2015-11-01

Full Text Available In 1933, Meissner and Ochsenfeld reported the expulsion of magnetic flux—the diamagnetic Meissner effect—from the interior of superconducting lead. This discovery was crucial in formulating the Bardeen-Cooper-Schrieffer (BCS theory of superconductivity. In exotic superconducting systems BCS theory does not strictly apply. A classical example is a superconductor-magnet hybrid system where magnetic ordering breaks time-reversal symmetry of the superconducting condensate and results in the stabilization of an odd-frequency superconducting state. It has been predicted that under appropriate conditions, odd-frequency superconductivity should manifest in the Meissner state as fluctuations in the sign of the magnetic susceptibility, meaning that the superconductivity can either repel (diamagnetic or attract (paramagnetic external magnetic flux. Here, we report local probe measurements of faint magnetic fields in a Au/Ho/Nb trilayer system using low-energy muons, where antiferromagnetic Ho (4.5 nm breaks time-reversal symmetry of the proximity-induced pair correlations in Au. From depth-resolved measurements below the superconducting transition of Nb, we observe a local enhancement of the magnetic field in Au that exceeds the externally applied field, thus proving the existence of an intrinsic paramagnetic Meissner effect arising from an odd-frequency superconducting state.

BOOK REVIEW: Symmetry Breaking

Science.gov (United States)

Ryder, L. H.

2005-11-01

One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would

Temperature effects on the nuclear symmetry energy and symmetry free energy with an isospin and momentum dependent interaction

International Nuclear Information System (INIS)

Xu, Jun; Ma, Hong-Ru; Chen, Lie-Wen; Li, Bao-An

2007-01-01

Within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, we investigate the temperature dependence of the symmetry energy E sym (ρ,T) and symmetry free energy F sym (ρ,T) for hot, isospin asymmetric nuclear matter. It is shown that the symmetry energy E sym (ρ,T) generally decreases with increasing temperature while the symmetry free energy F sym (ρ,T) exhibits opposite temperature dependence. The decrement of the symmetry energy with temperature is essentially due to the decrement of the potential energy part of the symmetry energy with temperature. The difference between the symmetry energy and symmetry free energy is found to be quite small around the saturation density of nuclear matter. While at very low densities, they differ significantly from each other. In comparison with the experimental data of temperature dependent symmetry energy extracted from the isotopic scaling analysis of intermediate mass fragments (IMF's) in heavy-ion collisions, the resulting density and temperature dependent symmetry energy E sym (ρ,T) is then used to estimate the average freeze-out density of the IMF's

Charge independence and charge symmetry

Energy Technology Data Exchange (ETDEWEB)

Miller, G A [Washington Univ., Seattle, WA (United States). Dept. of Physics; van Oers, W T.H. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Physics; [TRIUMF, Vancouver, BC (Canada)

1994-09-01

Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed. (author). 145 refs., 3 tabs., 11 figs.

Charge independence and charge symmetry

International Nuclear Information System (INIS)

Miller, G.A.

1994-09-01

Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed. (author). 145 refs., 3 tabs., 11 figs

Symmetry, from Euclid to Pierre Curie

International Nuclear Information System (INIS)

Sivardiere, J.

1997-01-01

A historical review of the principles of symmetry is presented, starting with Egyptian pavements and Euclid regular polyhedrons, 2 and 3 dimensional paving studies with Kepler in the 17. century, modern crystallography with the constant angle law and the rational truncations law in the 18. century, the identification of the various crystal symmetries (19. century), the discovery of liquid crystals, the relations between the symmetry and the physical and optical properties of systems, molecules, etc.. Finally, P. Curie has determined the general principle of symmetry, linking symmetry and its effects

Physics from symmetry

CERN Document Server

Schwichtenberg, Jakob

2018-01-01

This is a textbook that derives the fundamental theories of physics from symmetry. It starts by introducing, in a completely self-contained way, all mathematical tools needed to use symmetry ideas in physics. Thereafter, these tools are put into action and by using symmetry constraints, the fundamental equations of Quantum Mechanics, Quantum Field Theory, Electromagnetism, and Classical Mechanics are derived. As a result, the reader is able to understand the basic assumptions behind, and the connections between the modern theories of physics. The book concludes with first applications of the previously derived equations. Thanks to the input of readers from around the world, this second edition has been purged of typographical errors and also contains several revised sections with improved explanations. .

A reply to comment on "An experimental study of symmetry lowering of analcime"

Science.gov (United States)

Kyono, Atsushi

2018-04-01

The fracture surfaces of analcimes reported by Sugano and Kyono (Phys Chem Miner, 2018) were re-investigated using field-emission scanning electron microscopy. The results of scanning electron microscopic observation show the fractures can be characterized by smoothly curved surfaces, called sub-conchoidal fracture, and neither the lamellar twin nor the domain walls of twin were found on the surfaces of the analcimes. In addition, the lamellar twin is generally formed by transformation from the high-temperature phase or from pseudomorphic replacement under strong alkaline conditions. Actually, the symmetry lowering of analcime reported by Sugano and Kyono (2018) occurs at 200 °C. The temperature is much lower than the transformation from the high-temperature phase. In the hydrothermal experiment (Sugano and Kyono 2018), moreover, the analcimes were synthesized under acidic condition and reheated in pure water. No twin domain is likely to be formed under the hydrothermal condition. These facts strongly deny the possibility that the twin domains cause the pseudo-symmetry of tetragonal analcime. Consequently, it can be concluded that the observed forbidden reflections for the cubic Ia3 d symmetry are not due to the presence of twin domains, but due to the symmetry lowering of analcime from cubic Ia3 d to orthorhombic Ibca.

Discrete symmetries in periodic-orbit theory

International Nuclear Information System (INIS)

Robbins, J.M.

1989-01-01

The application of periodic-orbit theory to systems which possess a discrete symmetry is considered. A semiclassical expression for the symmetry-projected Green's function is obtained; it involves a sum over classical periodic orbits on a symmetry-reduced phase space, weighted by characters of the symmetry group. These periodic orbits correspond to trajectories on the full phase space which are not necessarily periodic, but whose end points are related by symmetry. If the symmetry-projected Green's functions are summed, the contributions of the unperiodic orbits cancel, and one recovers the usual periodic-orbit sum for the full Green's function. Several examples are considered, including the stadium billiard, a particle in a periodic potential, the Sinai billiard, the quartic oscillator, and the rotational spectrum of SF 6

Spin, mass, and symmetry

Energy Technology Data Exchange (ETDEWEB)

Peskin, M.E. [Stanford Univ., CA (United States)

1994-12-01

When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.

Spin, mass, and symmetry

International Nuclear Information System (INIS)

Peskin, M.E.

1994-01-01

When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics

Segmentation Using Symmetry Deviation

DEFF Research Database (Denmark)

Hollensen, Christian; Højgaard, L.; Specht, L.

2011-01-01

of the CT-scans into a single atlas. Afterwards the standard deviation of anatomical symmetry for the 20 normal patients was evaluated using non-rigid registration and registered onto the atlas to create an atlas for normal anatomical symmetry deviation. The same non-rigid registration was used on the 10...... hypopharyngeal cancer patients to find anatomical symmetry and evaluate it against the standard deviation of the normal patients to locate pathologic volumes. Combining the information with an absolute PET threshold of 3 Standard uptake value (SUV) a volume was automatically delineated. The overlap of automated....... The standard deviation of the anatomical symmetry, seen in figure for one patient along CT and PET, was extracted for normal patients and compared with the deviation from cancer patients giving a new way of determining cancer pathology location. Using the novel method an overlap concordance index...

Fifty years of symmetry operations

International Nuclear Information System (INIS)

Wigner, E.P.

1978-01-01

The author begins by discussing the application of symmetry principles in classical physics, which began 150 years ago. He then offers a few remarks on the essence of these principles and their role in the structure of physics; events, laws of nature, and invariance principles - kinematic and then dynamic - are treated. After this general discussion of the various types of symmetries, he considers the fundamental differences in their application in classical and quantum physics; the symmetry principles have greater effectiveness in quantum theory. After a few critical remarks of a general nature on the invariance principles, the author reviews the application of symmetry principles in various areas of quantum mechanics: atomic spectra, molecular physics, solid state physics, nuclear physics, and particle physics. He notes that the role of the different symmetries recognized to be approximate provide the most interesting conclusions

Axions from chiral family symmetry

International Nuclear Information System (INIS)

Chang, D.; Pal, P.B.; Maryland Univ., College Park; Senjanovic, G.

1985-01-01

We investigate the possibility that family symmetry, Gsub(F), is spontaneously broken chiral global symmetry. We classify the interesting cases when family symmetry can result in an automatic Peccei-Quinn symmetry U(1)sub(PQ) and thus provide a solution to the strong CP problem. The result disfavors having two or four families. For more than four families, U(1)sub(PQ) is in general automatic. In the case of three families, a unique Higgs sector allows U(1)sub(PQ) in the simplest case of Gsub(F)=[SU(3)] 3 . Cosmological consideration also puts strong constraint on the number of families. For Gsub(F)=[SU(N)] 3 cosmology singles out the three-family (N=3) case as a unique solution if there are three light neutrinos. Possible implication of decoupling theorem as applied to family symmetry breaking is also discussed. (orig.)

Symmetries of dynamically equivalent theories

Energy Technology Data Exchange (ETDEWEB)

Gitman, D.M.; Tyutin, I.V. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Lebedev Physics Institute, Moscow (Russian Federation)

2006-03-15

A natural and very important development of constrained system theory is a detail study of the relation between the constraint structure in the Hamiltonian formulation with specific features of the theory in the Lagrangian formulation, especially the relation between the constraint structure with the symmetries of the Lagrangian action. An important preliminary step in this direction is a strict demonstration, and this is the aim of the present article, that the symmetry structures of the Hamiltonian action and of the Lagrangian action are the same. This proved, it is sufficient to consider the symmetry structure of the Hamiltonian action. The latter problem is, in some sense, simpler because the Hamiltonian action is a first-order action. At the same time, the study of the symmetry of the Hamiltonian action naturally involves Hamiltonian constraints as basic objects. One can see that the Lagrangian and Hamiltonian actions are dynamically equivalent. This is why, in the present article, we consider from the very beginning a more general problem: how the symmetry structures of dynamically equivalent actions are related. First, we present some necessary notions and relations concerning infinitesimal symmetries in general, as well as a strict definition of dynamically equivalent actions. Finally, we demonstrate that there exists an isomorphism between classes of equivalent symmetries of dynamically equivalent actions. (author)

Symmetry analysis in the investigation of the order-disorder phase transition and possible structural deformations

Energy Technology Data Exchange (ETDEWEB)

Gurin, O V; Syromyatnikov, V N [AN SSSR, Sverdlovsk. Inst. Fiziki Metallov; Sikora, W [Joint Inst. for Nuclear Research, Dubna (USSR)

1984-08-01

Order-disorder phase transitions for the Me-X structures in Nb-H(D) hydrides with hydrogen (deuterium) ordering over the 12d tetrahedral interstices of the GAMMAsub(c)sup(v) lattice and for the Me-X and Me-X/sub 2/ oxides in the Ta-O system with oxygen ordering over octahedral 6b interstices are presented. The concentration of interstitial atoms is assumed to be constant. All possible models of ordered structures with a GAMMAsub(o)sup(b) lattice were determined using symmetry analysis. The possible structural deformations consistent with each variant of the ordering of the interstitial atoms were also considered. The structural deformations include the displacements of the metal atoms and of the centres of the interstices which were deduced using symmetry analysis. The results of the analysis of the final structure symmetry raise the question of understanding the nature of superstructure reflections in neutron diffraction patterns.

Linking partial and quasi dynamical symmetries in rotational nuclei and shell evolution in {sup 96}Zr

Energy Technology Data Exchange (ETDEWEB)

Kremer, Christoph

2016-01-27

The first part of this thesis revolves around symmetries in the sd-IBA-1. A region of approximate O(6) symmetry for the ground-state band, a partial dynamical symmetry (PDS) of type III, in the parameter space of the extended consistent-Q formalism is identified through quantum number fluctuations. The simultaneous occurrence of a SU(3) quasi dynamical symmetry for nuclei in the region of O(6) PDS is explained via the β=1, γ=0 intrinsic state underlying the ground-state band. The previously unrelated concepts of PDS and QDS are connected for the first time and many nuclei in the rare earth region that approximately satisfy both symmetry requirements are identified. Ground-state to ground-state (p, t) transfer reactions are presented as an experimental signature to identify pairs of nuclei that both exhibit O(6) PDS. In the second part of this thesis inelastic electron scattering off {sup 96}Zr is studied. The experiment was performed at the high resolution Lintott spectrometer at the S-DALINAC and covered a momentum-transfer range of 0.28 - 0.59 fm{sup -1}. Through a relative analysis using Plane Wave Born Approximation (PWBA) the B(E2;2{sup +}{sub 2}→0{sup +}{sub 1}) value is extracted without incurring the additional model dependence of a Distorted Wave Born Approximation (DWBA). By combining this result with known multipole mixing ratios and branching ratios all decay strengths of the 2{sup +}{sub 2} state are determined. A mixing calculation establishes very weak mixing (V{sub mix}=76 keV) between states of the ground-state band and those of the band build on top of the 0{sup +}{sub 2} state which includes the 2{sup +}{sub 2} state. The occurrence of these two isolated bands is interpreted within the shell model in terms of type II shell evolution.

Charged fluids with symmetries

Indian Academy of Sciences (India)

It is possible to introduce many types of symmetries on the manifold which restrict the ... metric tensor field and generate constants of the motion along null geodesics .... In this analysis we have studied the role of symmetries for charged perfect ...

Wigner's Symmetry Representation Theorem

Indian Academy of Sciences (India)

IAS Admin

At the Heart of Quantum Field Theory! Aritra Kr. ... principle of symmetry was not held as something very fundamental ... principle of local symmetry: the laws of physics are invariant un- .... Next, we would show that different coefficients of a state ...

Summary: Symmetries and spin

International Nuclear Information System (INIS)

Haxton, W.C.

1988-01-01

I discuss a number of the themes of the Symmetries and Spin session of the 8th International Symposium on High Energy Spin Physics: parity nonconservation, CP/T nonconservation, and tests of charge symmetry and charge independence. 28 refs., 1 fig

Symmetry chains for the atomic shell model. I. Classification of symmetry chains for atomic configurations

International Nuclear Information System (INIS)

Gruber, B.; Thomas, M.S.

1980-01-01

In this article the symmetry chains for the atomic shell model are classified in such a way that they lead from the group SU(4l+2) to its subgroup SOsub(J)(3). The atomic configurations (nl)sup(N) transform like irreducible representations of the group SU(4l+2), while SOsub(J)(3) corresponds to total angular momentum in SU(4l+2). The defining matrices for the various embeddings are given for each symmetry chain that is obtained. These matrices also define the projection onto the weight subspaces for the corresponding subsymmetries and thus relate the various quantum numbers and determine the branching of representations. It is shown in this article that three (interrelated) symmetry chains are obtained which correspond to L-S coupling, j-j coupling, and a seniority dependent coupling. Moreover, for l<=6 these chains are complete, i.e., there are no other chains but these. In articles to follow, the symmetry chains that lead from the group SO(8l+5) to SOsub(J)(3) will be discussed, with the entire atomic shell transforming like an irreducible representation of SO(8l+5). The transformation properties of the states of the atomic shell will be determined according to the various symmetry chains obtained. The symmetry lattice discussed in this article forms a sublattice of the larger symmetry lattice with SO(8l+5) as supergroup. Thus the transformation properties of the states of the atomic configurations, according to the various symmetry chains discussed in this article, will be obtained too. (author)

Neutrino mixing: from the broken μ-τ symmetry to the broken Friedberg–Lee symmetry

International Nuclear Information System (INIS)

Xing, Zhizhong

2007-01-01

I argue that the observed flavor structures of leptons and quarks might imply the existence of certain flavor symmetries. The latter should be a good starting point to build realistic models towards deeper understanding of the fermion mass spectra and flavor mixing patterns. The μ-τ permutation symmetry serves for such an example to interpret the almost maximal atmospheric neutrino mixing angle (θ 23 ~ 45°) and the strongly suppressed CHOOZ neutrino mixing angle (θ 13 < 10°). In this talk I like to highlight a new kind of flavor symmetry, the Friedberg–Lee symmetry, for the effective Majorana neutrino mass operator. Luo and I have shown that this symmetry can be broken in an oblique way, such that the lightest neutrino remains massless but an experimentally-favored neutrino mixing pattern is achievable. We get a novel prediction for θ 13 in the CP-conserving case: sinθ 13 = tanθ 12 |(1 - tanθ 23 )/(1 + tanθ 23 )|. Our scenario can simply be generalized to accommodate CP violation and be combined with the seesaw mechanism. Finally I stress the importance of probing possible effects of μ-τ symmetry breaking either in terrestrial neutrino oscillation experiments or with ultrahigh-energy cosmic neutrino telescopes. (author)

Emergence of Symmetries from Entanglement

CERN Multimedia

CERN. Geneva

2016-01-01

Maximal Entanglement appears to be a key ingredient for the emergence of symmetries. We first illustrate this phenomenon using two examples: the emergence of conformal symmetry in condensed matter systems and  the relation of tensor networks to holography. We further present a Principle of Maximal Entanglement that seems to dictate to a large extend the structure of gauge symmetry.

Symmetry energy in nuclear surface

International Nuclear Information System (INIS)

Danielewicz, P.; Lee, Jenny

2009-01-01

Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. That interplay gives rise to the mass dependence of the symmetry coefficient in an energy formula. Charge symmetry of the nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of the magnitude of neutron-proton asymmetry. (author)

Remembering the real me: Nostalgia offers a window to the intrinsic self.

Science.gov (United States)

Baldwin, Matthew; Biernat, Monica; Landau, Mark J

2015-01-01

Seven studies reveal that nostalgia, a sentimental affection for the past, offers a window to the intrinsic self-concept-who people think they truly are. In Study 1, state nostalgia was associated with higher authenticity and lower extrinsic self-focus (concern with meeting extrinsic value standards). In Study 2, experimentally primed nostalgia increased perceived authenticity of the past self, which in turn predicted reduced current extrinsic self-focus. Study 3 showed that nostalgia increased the accessibility of the intrinsic self-concept but not the everyday self-concept. Study 4 provided evidence for a moderator suggested by our theoretical analysis: Recalling a nostalgic event increased felt nostalgia and positive affect, but this effect was attenuated if participants were prompted to recognize external factors controlling their behavior during that event. Next we treated nostalgia as an outcome variable and a moderator to test whether nostalgia is triggered by, and buffers against, threats to the intrinsic self. Using a mediation approach, Study 5 showed that participants primed to feel blocked in intrinsic self-expression responded with increased nostalgia. In Study 6, intrinsic self-threat reduced intrinsic self-expression and subjective well-being for participants who were not given an opportunity to respond with nostalgia but not for participants who were allowed to reflect on a nostalgic memory. In line with the experimental findings, correlational data from Study 7 indicated that dispositional nostalgia positively predicted intrinsic self-expression and well-being. Understanding nostalgia as a window to the intrinsic self points to new directions for research on nostalgia's antecedents, moderators, and consequences for well-being. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Symmetry, winding number, and topological charge of vortex solitons in discrete-symmetry media

International Nuclear Information System (INIS)

Garcia-March, Miguel-Angel; Zacares, Mario; Ferrando, Albert; Sahu, Sarira; Ceballos-Herrera, Daniel E.

2009-01-01

We determine the functional behavior near the discrete rotational symmetry axis of discrete vortices of the nonlinear Schroedinger equation. We show that these solutions present a central phase singularity whose charge is restricted by symmetry arguments. Consequently, we demonstrate that the existence of high-charged discrete vortices is related to the presence of other off-axis phase singularities, whose positions and charges are also restricted by symmetry arguments. To illustrate our theoretical results, we offer two numerical examples of high-charged discrete vortices in photonic crystal fibers showing hexagonal discrete rotational invariance.

Discrete symmetries in the MSSM

Energy Technology Data Exchange (ETDEWEB)

Schieren, Roland

2010-12-02

The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z{sup R}{sub 4} symmetry is discovered which solves the {mu}-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z{sup R}{sub 4} is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z{sup R}{sub 4} symmetry and other desirable features. (orig.)

Discrete symmetries in the MSSM

International Nuclear Information System (INIS)

Schieren, Roland

2010-01-01

The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z R 4 symmetry is discovered which solves the μ-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z R 4 is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z R 4 symmetry and other desirable features. (orig.)

SymPS: BRDF Symmetry Guided Photometric Stereo for Shape and Light Source Estimation.

Science.gov (United States)

Lu, Feng; Chen, Xiaowu; Sato, Imari; Sato, Yoichi

2018-01-01

We propose uncalibrated photometric stereo methods that address the problem due to unknown isotropic reflectance. At the core of our methods is the notion of "constrained half-vector symmetry" for general isotropic BRDFs. We show that such symmetry can be observed in various real-world materials, and it leads to new techniques for shape and light source estimation. Based on the 1D and 2D representations of the symmetry, we propose two methods for surface normal estimation; one focuses on accurate elevation angle recovery for surface normals when the light sources only cover the visible hemisphere, and the other for comprehensive surface normal optimization in the case that the light sources are also non-uniformly distributed. The proposed robust light source estimation method also plays an essential role to let our methods work in an uncalibrated manner with good accuracy. Quantitative evaluations are conducted with both synthetic and real-world scenes, which produce the state-of-the-art accuracy for all of the non-Lambertian materials in MERL database and the real-world datasets.

Elliptic-symmetry vector optical fields.

Science.gov (United States)

Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

2014-08-11

We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on.

Sequence selection by dynamical symmetry breaking in an autocatalytic binary polymer model

DEFF Research Database (Denmark)

Fellermann, Harold; Tanaka, Shinpei; Rasmussen, Steen

2017-01-01

Template-directed replication of nucleic acids is at the essence of all living beings and a major milestone for any origin of life scenario. We present an idealized model of prebiotic sequence replication, where binary polymers act as templates for their autocatalytic replication, thereby serving...... as each others reactants and products in an intertwined molecular ecology. Our model demonstrates how autocatalysis alters the qualitative and quantitative system dynamics in counterintuitive ways. Most notably, numerical simulations reveal a very strong intrinsic selection mechanism that favors...... the appearance of a few population structures with highly ordered and repetitive sequence patterns when starting from a pool of monomers. We demonstrate both analytically and through simulation how this "selection of the dullest" is caused by continued symmetry breaking through random fluctuations...

Approximate reflection coefficients for a thin VTI layer

KAUST Repository

Hao, Qi

2017-09-18

We present an approximate method to derive simple expressions for the reflection coefficients of P- and SV-waves for a thin transversely isotropic layer with a vertical symmetry axis (VTI) embedded in a homogeneous VTI background. The layer thickness is assumed to be much smaller than the wavelengths of P- and SV-waves inside. The exact reflection and transmission coefficients are derived by the propagator matrix method. In the case of normal incidence, the exact reflection and transmission coefficients are expressed in terms of the impedances of vertically propagating P- and S-waves. For subcritical incidence, the approximate reflection coefficients are expressed in terms of the contrast in the VTI parameters between the layer and the background. Numerical examples are designed to analyze the reflection coefficients at normal and oblique incidence, and investigate the influence of transverse isotropy on the reflection coefficients. Despite giving numerical errors, the approximate formulae are sufficiently simple to qualitatively analyze the variation of the reflection coefficients with the angle of incidence.

Quantum symmetry for pedestrians

International Nuclear Information System (INIS)

Mack, G.; Schomerus, V.

1992-03-01

Symmetries more general than groups are possible in quantum therory. Quantum symmetries in the narrow sense are compatible with braid statistics. They are theoretically consistent much as supersymmetry is, and they could lead to degenerate multiplets of excitations with fractional spin in thin films. (orig.)

Sequential flavor symmetry breaking

International Nuclear Information System (INIS)

Feldmann, Thorsten; Jung, Martin; Mannel, Thomas

2009-01-01

The gauge sector of the standard model exhibits a flavor symmetry that allows for independent unitary transformations of the fermion multiplets. In the standard model the flavor symmetry is broken by the Yukawa couplings to the Higgs boson, and the resulting fermion masses and mixing angles show a pronounced hierarchy. In this work we connect the observed hierarchy to a sequence of intermediate effective theories, where the flavor symmetries are broken in a stepwise fashion by vacuum expectation values of suitably constructed spurion fields. We identify the possible scenarios in the quark sector and discuss some implications of this approach.

Sequential flavor symmetry breaking

Science.gov (United States)

Feldmann, Thorsten; Jung, Martin; Mannel, Thomas

2009-08-01

The gauge sector of the standard model exhibits a flavor symmetry that allows for independent unitary transformations of the fermion multiplets. In the standard model the flavor symmetry is broken by the Yukawa couplings to the Higgs boson, and the resulting fermion masses and mixing angles show a pronounced hierarchy. In this work we connect the observed hierarchy to a sequence of intermediate effective theories, where the flavor symmetries are broken in a stepwise fashion by vacuum expectation values of suitably constructed spurion fields. We identify the possible scenarios in the quark sector and discuss some implications of this approach.

Strong intrinsic motivation

OpenAIRE

Dessi, Roberta; Rustichini, Aldo

2015-01-01

A large literature in psychology, and more recently in economics, has argued that monetary rewards can reduce intrinsic motivation. We investigate whether the negative impact persists when intrinsic motivation is strong, and test this hypothesis experimentally focusing on the motivation to undertake interesting and challenging tasks, informative about individual ability. We find that this type of task can generate strong intrinsic motivation, that is impervious to the effect of monetary incen...

Hybrid local-order mechanism for inversion symmetry breaking

Science.gov (United States)

Wolpert, Emma H.; Overy, Alistair R.; Thygesen, Peter M. M.; Simonov, Arkadiy; Senn, Mark S.; Goodwin, Andrew L.

2018-04-01

Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarization from local displacements on the square and cubic lattices. Our model contains two key ingredients: a Kitaev-like orientation-dependent interaction between nearest neighbors and a steric term that acts between next-nearest neighbors. Taken by themselves, each of these two ingredients is incapable of driving long-range symmetry breaking, despite the presence of a broad feature in the corresponding heat-capacity functions. Instead, each component results in a "hidden" transition on cooling to a manifold of degenerate states; the two manifolds are different in the sense that they reflect distinct types of local order. Remarkably, their intersection, i.e., the ground state when both interaction terms are included in the Hamiltonian, supports a spontaneous polarization. In this way, our study demonstrates how local-order mechanisms might be combined to break global inversion symmetry in a manner conceptually similar to that operating in the "hybrid" improper ferroelectrics. We discuss the relevance of our analysis to the emergence of spontaneous polarization in well-studied ferroelectrics such as BaTiO3 and KNbO3.

Inter-subject Functional Correlation Reveal a Hierarchical Organization of Extrinsic and Intrinsic Systems in the Brain.

Science.gov (United States)

Ren, Yudan; Nguyen, Vinh Thai; Guo, Lei; Guo, Christine Cong

2017-09-07

The brain is constantly monitoring and integrating both cues from the external world and signals generated intrinsically. These extrinsically and intrinsically-driven neural processes are thought to engage anatomically distinct regions, which are thought to constitute the extrinsic and intrinsic systems of the brain. While the specialization of extrinsic and intrinsic system is evident in primary and secondary sensory cortices, a systematic mapping of the whole brain remains elusive. Here, we characterized the extrinsic and intrinsic functional activities in the brain during naturalistic movie-viewing. Using a novel inter-subject functional correlation (ISFC) analysis, we found that the strength of ISFC shifts along the hierarchical organization of the brain. Primary sensory cortices appear to have strong inter-subject functional correlation, consistent with their role in processing exogenous information, while heteromodal regions that attend to endogenous processes have low inter-subject functional correlation. Those brain systems with higher intrinsic tendency show greater inter-individual variability, likely reflecting the aspects of brain connectivity architecture unique to individuals. Our study presents a novel framework for dissecting extrinsically- and intrinsically-driven processes, as well as examining individual differences in brain function during naturalistic stimulation.

Symmetries in discrete-time mechanics

International Nuclear Information System (INIS)

Khorrami, M.

1996-01-01

Based on a general formulation for discrete-time quantum mechanics, introduced by M. Khorrami (Annals Phys. 224 (1995), 101), symmetries in discrete-time quantum mechanics are investigated. It is shown that any classical continuous symmetry leads to a conserved quantity in classical mechanics, as well as quantum mechanics. The transformed wave function, however, has the correct evolution if and only if the symmetry is nonanomalous. Copyright copyright 1996 Academic Press, Inc

Symmetry and electromagnetism. Simetria y electromagnetismo

Energy Technology Data Exchange (ETDEWEB)

Fuentes Cobas, L.E.; Font Hernandez, R.

1993-01-01

An analytical treatment of electrostatic and magnetostatic field symmetry, as a function of charge and current distribution symmetry, is proposed. The Newmann Principle, related to the cause-effect symmetry relation, is presented and applied to the characterization of simple configurations. (Author) 5 refs.

Statistical symmetries in physics

International Nuclear Information System (INIS)

Green, H.S.; Adelaide Univ., SA

1994-01-01

Every law of physics is invariant under some group of transformations and is therefore the expression of some type of symmetry. Symmetries are classified as geometrical, dynamical or statistical. At the most fundamental level, statistical symmetries are expressed in the field theories of the elementary particles. This paper traces some of the developments from the discovery of Bose statistics, one of the two fundamental symmetries of physics. A series of generalizations of Bose statistics is described. A supersymmetric generalization accommodates fermions as well as bosons, and further generalizations, including parastatistics, modular statistics and graded statistics, accommodate particles with properties such as 'colour'. A factorization of elements of ggl(n b ,n f ) can be used to define truncated boson operators. A general construction is given for q-deformed boson operators, and explicit constructions of the same type are given for various 'deformed' algebras. A summary is given of some of the applications and potential applications. 39 refs., 2 figs

Molecular symmetry and spectroscopy

CERN Document Server

Bunker, Philip; Jensen, Per

2006-01-01

The first edition, by P.R. Bunker, published in 1979, remains the sole textbook that explains the use of the molecular symmetry group in understanding high resolution molecular spectra. Since 1979 there has been considerable progress in the field and a second edition is required; the original author has been joined in its writing by Per Jensen. The Material of the first edition has been reorganized and much has been added. The molecular symmetry group is now introduced early on, and the explanation of how to determine nuclear spin statistical weights has been consolidated in one chapter, after groups, symmetry groups, character tables and the Hamiltonian have been introduced. A description of the symmetry in the three-dimensional rotation group K(spatial), irreducible spherical tensor operators, and vector coupling coefficients is now included. The chapters on energy levels and selection rules contain a great deal of material that was not in the first edition (much of it was undiscovered in 1979), concerning ...

Symmetries in fundamental physics

CERN Document Server

Sundermeyer, Kurt

2014-01-01

Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P.Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also underst...

Symmetries in fundamental physics

CERN Document Server

Sundermeyer, Kurt

2014-01-01

Over the course of the last century it has become clear that both elementary particle physics and relativity theories are based on the notion of symmetries. These symmetries become manifest in that the "laws of nature" are invariant under spacetime transformations and/or gauge transformations. The consequences of these symmetries were analyzed as early as in 1918 by Emmy Noether on the level of action functionals. Her work did not receive due recognition for nearly half a century, but can today be understood as a recurring theme in classical mechanics, electrodynamics and special relativity, Yang-Mills type quantum field theories, and in general relativity. As a matter of fact, as shown in this monograph, many aspects of physics can be derived solely from symmetry considerations. This substantiates the statement of E.P. Wigner "... if we knew all the laws of nature, or the ultimate Law of nature, the invariance properties of these laws would not furnish us new information." Thanks to Wigner we now also unders...

Intrinsic Motivation.

Science.gov (United States)

Deci, Edward L.

The paper draws together a wide variety of research which relates to the topic of intrinsic motivation; intrinsically motivated activities are defined as those which a person does for no apparent reward except the activity itself or the feelings which result from the activity. Most of this research was not originally reported within the framework…

Motor memory is encoded as a gain-field combination of intrinsic and extrinsic action representations.

Science.gov (United States)

Brayanov, Jordan B; Press, Daniel Z; Smith, Maurice A

2012-10-24

Actions can be planned in either an intrinsic (body-based) reference frame or an extrinsic (world-based) frame, and understanding how the internal representations associated with these frames contribute to the learning of motor actions is a key issue in motor control. We studied the internal representation of this learning in human subjects by analyzing generalization patterns across an array of different movement directions and workspaces after training a visuomotor rotation in a single movement direction in one workspace. This provided a dense sampling of the generalization function across intrinsic and extrinsic reference frames, which allowed us to dissociate intrinsic and extrinsic representations and determine the manner in which they contributed to the motor memory for a trained action. A first experiment showed that the generalization pattern reflected a memory that was intermediate between intrinsic and extrinsic representations. A second experiment showed that this intermediate representation could not arise from separate intrinsic and extrinsic learning. Instead, we find that the representation of learning is based on a gain-field combination of local representations in intrinsic and extrinsic coordinates. This gain-field representation generalizes between actions by effectively computing similarity based on the (Mahalanobis) distance across intrinsic and extrinsic coordinates and is in line with neural recordings showing mixed intrinsic-extrinsic representations in motor and parietal cortices.

Intrinsic and Extrinsic Motivation, Orientation and Achievements in L2 of Arab Learners of English, French and German: A Study from Jordan

Science.gov (United States)

Kreishan, Lana J.; Al-Dhaimat, Yahya

2013-01-01

The aim of this research is to explore Jordanian undergraduate students' intrinsic and extrinsic motivations and instrumental and integrative orientations toward learning English, French, and German as foreign languages. The paper also reflects on how subtypes of intrinsic and extrinsic motivations relate to orientations and examines possible…

Intrinsic contractures of the hand.

Science.gov (United States)

Paksima, Nader; Besh, Basil R

2012-02-01

Contractures of the intrinsic muscles of the fingers disrupt the delicate and complex balance of intrinsic and extrinsic muscles, which allows the hand to be so versatile and functional. The loss of muscle function primarily affects the interphalangeal joints but also may affect etacarpophalangeal joints. The resulting clinical picture is often termed, intrinsic contracture or intrinsic-plus hand. Disruption of the balance between intrinsic and extrinsic muscles has many causes and may be secondary to changes within the intrinsic musculature or the tendon unit. This article reviews diagnosis, etiology, and treatment algorithms in the management of intrinsic contractures of the fingers. Copyright © 2012 Elsevier Inc. All rights reserved.

Discrete symmetries and their stringy origin

International Nuclear Information System (INIS)

Mayorga Pena, Damian Kaloni

2014-05-01

Discrete symmetries have proven to be very useful in controlling the phenomenology of theories beyond the standard model. In this work we explore how these symmetries emerge from string compactifications. Our approach is twofold: On the one hand, we consider the heterotic string on orbifold backgrounds. In this case the discrete symmetries can be derived from the orbifold conformal field theory, and it can be shown that they are in close relation with the orbifold geometry. We devote special attention to R-symmetries, which arise from discrete remnants of the Lorentz group in compact space. Further we discuss the physical implications of these symmetries both in the heterotic mini-landscape and in newly constructed models based on the Z 2 x Z 4 orbifold. In both cases we observe that the discrete symmetries favor particular locations in the orbifold where the particles of standard model should live. On the other hand we consider a class of F-theory models exhibiting an SU(5) gauge group, times additional U(1) symmetries. In this case, the smooth compactification background does not permit us to track the discrete symmetries as transparently as in orbifold models. Hence, we follow a different approach and search for discrete subgroups emerging after the U(1)s are broken. We observe that in this approach it is possible to obtain the standard Z 2 matter parity of the MSSM.

Prediction of Human Eye Fixations using Symmetry

OpenAIRE

Kootstra, Gert; Schomaker, Lambert R. B.

2009-01-01

Humans are very sensitive to symmetry in visual patterns. Reaction time experiments show that symmetry is detected and recognized very rapidly. This suggests that symmetry is a highly salient feature. Existing computational models of saliency, however, have mainly focused on contrast as a measure of saliency. In this paper, we discuss local symmetry as a measure of saliency. We propose a number of symmetry models and perform an eye-tracking study with human participants viewing photographic i...

Natural R parity conservation with horizontal symmetries: A four generation model

International Nuclear Information System (INIS)

Berezhiani, Z.; Nardi, E.

1995-01-01

In most supersymmetric models the stability of the proton is ensured by invoking R parity. A necessary ingredient to enforce R parity is the possibility of distinguishing the lepton superfields from the Higgs ones. This is generally achieved either by assuming different charges under some matter parity, or by assigning the superfields to different representations of a unified gauge group. We want to put forward the idea that the replica of the fermion generations, which constitute an intrinsic difference between the fermions and the Higgs superfields, can give a clue to understanding R parity as an accidental symmetry. More ambitiously, we suggest a possible relation between proton stability and the actual number of fermion generations. We carry out our investigation in the framework of non-Abelian horizontal gauge symmetries. We identify SU(4) H as the only acceptable horizontal gauge group which can naturally ensure the absence of R-parity-violating operators, without conflicting with other theoretical and phenomenological constraints. We analyze a version of the supersymmetric standard model equipped with a gauged horizontal SU(4) H , in which R parity is accidental. The model predicts four families of fermions, it allows for the dynamical generation of a realistic hierarchy of fermion masses without any ad hoc choice of small Yukawa couplings; it ensures in a natural way the heaviness of all the fourth family fermions (including the neutrino), and it predicts a lower limit for the τ-neutrino mass of a few eV. The scale of the breaking of the horizontal symmetry can be constrained rather precisely in a narrow window around ∼10 11 GeV. Some interesting astrophysical and cosmological implications of the model are addressed as well

Intrinsic and extrinsic mortality reunited

DEFF Research Database (Denmark)

Koopman, Jacob J E; Wensink, Maarten J; Rozing, Maarten P

2015-01-01

Intrinsic and extrinsic mortality are often separated in order to understand and measure aging. Intrinsic mortality is assumed to be a result of aging and to increase over age, whereas extrinsic mortality is assumed to be a result of environmental hazards and be constant over age. However......, allegedly intrinsic and extrinsic mortality have an exponentially increasing age pattern in common. Theories of aging assert that a combination of intrinsic and extrinsic stressors underlies the increasing risk of death. Epidemiological and biological data support that the control of intrinsic as well...... as extrinsic stressors can alleviate the aging process. We argue that aging and death can be better explained by the interaction of intrinsic and extrinsic stressors than by classifying mortality itself as being either intrinsic or extrinsic. Recognition of the tight interaction between intrinsic and extrinsic...

Human preferences for symmetry: subjective experience, cognitive conflict and cortical brain activity.

Directory of Open Access Journals (Sweden)

David W Evans

Full Text Available This study examines the links between human perceptions, cognitive biases and neural processing of symmetrical stimuli. While preferences for symmetry have largely been examined in the context of disorders such as obsessive-compulsive disorder and autism spectrum disorders, we examine various these phenomena in non-clinical subjects and suggest that such preferences are distributed throughout the typical population as part of our cognitive and neural architecture. In Experiment 1, 82 young adults reported on the frequency of their obsessive-compulsive spectrum behaviors. Subjects also performed an emotional Stroop or variant of an Implicit Association Task (the OC-CIT developed to assess cognitive biases for symmetry. Data not only reveal that subjects evidence a cognitive conflict when asked to match images of positive affect with asymmetrical stimuli, and disgust with symmetry, but also that their slowed reaction times when asked to do so were predicted by reports of OC behavior, particularly checking behavior. In Experiment 2, 26 participants were administered an oddball Event-Related Potential task specifically designed to assess sensitivity to symmetry as well as the OC-CIT. These data revealed that reaction times on the OC-CIT were strongly predicted by frontal electrode sites indicating faster processing of an asymmetrical stimulus (unparallel lines relative to a symmetrical stimulus (parallel lines. The results point to an overall cognitive bias linking disgust with asymmetry and suggest that such cognitive biases are reflected in neural responses to symmetrical/asymmetrical stimuli.

Application of structural symmetries in the plane-wave-based transfer-matrix method for three-dimensional photonic crystal waveguides

International Nuclear Information System (INIS)

Li Zhiyuan; Ho Kaiming

2003-01-01

The plane-wave-based transfer-matrix method (TMM) exhibits a peculiar advantage of being capable of solving eigenmodes involved in an infinite photonic crystal and electromagnetic (EM) wave propagation in finite photonic crystal slabs or even semi-infinite photonic crystal structures within the same theoretical framework. In addition, this theoretical approach can achieve much improved numerical convergency in solution of photonic band structures than the conventional plane-wave expansion method. In this paper we employ this TMM in combination with a supercell technique to handle two important kinds of three-dimensional (3D) photonic crystal waveguide structures. The first one is waveguides created in a 3D layer-by-layer photonic crystal that possesses a complete band gap, the other more popular one is waveguides built in a two-dimensional photonic crystal slab. These waveguides usually have mirror-reflection symmetries in one or two directions perpendicular to their axis. We have taken advantage of these structural symmetries to reduce the numerical burden of the TMM solution of the guided modes. The solution to the EM problems under these mirror-reflection symmetries in both the real space and the plane-wave space is discussed in a systematic way and in great detail. Both the periodic boundary condition and the absorbing boundary condition are employed to investigate structures with or without complete 3D optical confinement. The fact that the EM field components investigated in the TMM are collinear with the symmetric axes of the waveguide brings great convenience and clarity in exploring the eigenmode symmetry in both the real space and the plane-wave space. The classification of symmetry involved in the guided modes can help people to better understand the coupling of the photonic crystal waveguides with external channels such as dielectric slab or wire waveguides

Dynamical study of symmetries: breaking and restauration

International Nuclear Information System (INIS)

Schuck, P.

1986-09-01

First symmetry breaking (spontaneous) is explained and the physical implication discussed for infinite systems. The relation with phase transitions is indicated. Then the specific aspects of symmetry breaking in finite systems is treated and illustrated in detail for the case of translational invariance with the help of an oversimplified but exactly solvable model. The method of projection (restauration of symmetry) is explained for the static case and also applied to the model. Symmetry breaking in the dynamical case and for instance the notion of a soft mode responsible for the symmetry breaking is discussed in the case of superfluidity and another exactly solvable model is introduced. The Goldstone mode is treated in detail. Some remarks on analogies with the breaking of chiral symmetry are made. Some recent developments in the theory of symmetry restauration are briefly outlined [fr

The detrimental effects of extrinsic reinforcement on "Intrinsic motivation".

Science.gov (United States)

Dickinson, A M

1989-01-01

Extrinsic consequences have been criticized on the grounds that they decrease intrinsic motivation or internally initiated behavior. Two popular rationales for this criticism, Lepper's overjustification hypothesis (1981) and Deci's motivational theory (Deci & Ryan, 1985), are reviewed and the criticism is then redefined behaviorally. "Intrinsically controlled" behavior is defined as behavior maintained by response-produced reinforcers, and the question concerning extrinsic consequences is thus restated as follows: When behavior is maintained by response-produced stimuli, does extrinsic reinforcement decrease the reinforcing value of those stimuli? The empirical support for this detrimental effect is summarized briefly, and several possible explanations for the phenomenon are offered. Research results that reflect on the effect's generality and social significance are discussed next, with the conclusion that the effect is transient and not likely to occur at all if extrinsic rewards are reinforcing, noncompetitive, based on reasonable performance standards, and delivered repetitively.

Rigidity and symmetry

CERN Document Server

Weiss, Asia; Whiteley, Walter

2014-01-01

This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme.  Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology.  The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...

Neutrino masses and family symmetry

International Nuclear Information System (INIS)

Grinstein, B.; Preskill, J.; Wise, M.B.

1985-01-01

Neutrino masses in the 100 eV-1 MeV range are permitted if there is a spontaneously broken global family symmetry that allows the heavy neutrinos to decay by Goldstone boson emission with a cosmologically acceptable lifetime. The family symmetry may be either abelian or nonabelian; we present models illustrating both possibilities. If the family symmetry is nonabelian, then the decay tau -> μ + Goldstone boson or tau -> e + Goldstone may have an observable rate. (orig.)

Trieste lectures on mirror symmetry

Energy Technology Data Exchange (ETDEWEB)

Hori, K [Department of Physics and Department of Mathematics, University of Toronto, Toronto, Ontario (Canada)

2003-08-15

These are pedagogical lectures on mirror symmetry given at the Spring School in ICTP, Trieste, March 2002. The focus is placed on worldsheet descriptions of the physics related to mirror symmetry. We start with the introduction to general aspects of (2,2) supersymmetric field theories in 1 + 1 dimensions. We next move on to the study and applications of linear sigma model. Finally, we provide a proof of mirror symmetry in a class of models. (author)

Newton–Hooke-type symmetry of anisotropic oscillators

International Nuclear Information System (INIS)

Zhang, P.M.; Horvathy, P.A.; Andrzejewski, K.; Gonera, J.; Kosiński, P.

2013-01-01

Rotation-less Newton–Hooke-type symmetry, found recently in the Hill problem, and instrumental for explaining the center-of-mass decomposition, is generalized to an arbitrary anisotropic oscillator in the plane. Conversely, the latter system is shown, by the orbit method, to be the most general one with such a symmetry. Full Newton–Hooke symmetry is recovered in the isotropic case. Star escape from a galaxy is studied as an application. -- Highlights: ► Rotation-less Newton–Hooke (NH) symmetry is generalized to an arbitrary anisotropic oscillator. ► The orbit method is used to find the most general case for rotation-less NH symmetry. ► The NH symmetry is decomposed into Heisenberg algebras based on chiral decomposition

Big break for charge symmetry

CERN Document Server

Miller, G A

2003-01-01

Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of sup i sospin sup , and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while ...

A κ-symmetry calculus for superparticles

International Nuclear Information System (INIS)

Gauntlett, J.P.

1991-01-01

We develop a κ-symmetry calculus for the d=2 and d=3, N=2 massive superparticles, which enables us to construct higher order κ-invariant actions. The method relies on a reformulation of these models as supersymmetric sigma models that are invariant under local worldline superconformal transformations. We show that the κ-symmetry is embedded in the superconformal symmetry so that a calculus for the κ-symmetry is equivalent to a tensor calculus for the latter. We develop such a calculus without the introduction of a wordline supergravity multiplet. (orig.)

''Natural'' left-right symmetry

International Nuclear Information System (INIS)

Mohapatra, R.N.; Pati, J.C.

1975-01-01

It is remarked that left-right symmetry of the starting gauge interactions is retained as a ''natural'' symmetry if it is broken in no way except possibly by mass terms in the Lagrangian. The implications of this result for the unification of coupling constants and for parity nonconservation at low and high energies are stressed

Lie-algebra approach to symmetry breaking

International Nuclear Information System (INIS)

Anderson, J.T.

1981-01-01

A formal Lie-algebra approach to symmetry breaking is studied in an attempt to reduce the arbitrariness of Lagrangian (Hamiltonian) models which include several free parameters and/or ad hoc symmetry groups. From Lie algebra it is shown that the unbroken Lagrangian vacuum symmetry can be identified from a linear function of integers which are Cartan matrix elements. In broken symmetry if the breaking operators form an algebra then the breaking symmetry (or symmetries) can be identified from linear functions of integers characteristic of the breaking symmetries. The results are applied to the Dirac Hamiltonian of a sum of flavored fermions and colored bosons in the absence of dynamical symmetry breaking. In the partially reduced quadratic Hamiltonian the breaking-operator functions are shown to consist of terms of order g 2 , g, and g 0 in the color coupling constants and identified with strong (boson-boson), medium strong (boson-fermion), and fine-structure (fermion-fermion) interactions. The breaking operators include a boson helicity operator in addition to the familiar fermion helicity and ''spin-orbit'' terms. Within the broken vacuum defined by the conventional formalism, the field divergence yields a gauge which is a linear function of Cartan matrix integers and which specifies the vacuum symmetry. We find that the vacuum symmetry is chiral SU(3) x SU(3) and the axial-vector-current divergence gives a PCAC -like function of the Cartan matrix integers which reduces to PCAC for SU(2) x SU(2) breaking. For the mass spectra of the nonets J/sup P/ = 0 - ,1/2 + ,1 - the integer runs through the sequence 3,0,-1,-2, which indicates that the breaking subgroups are the simple Lie groups. Exact axial-vector-current conservation indicates a breaking sum rule which generates octet enhancement. Finally, the second-order breaking terms are obtained from the second-order spin tensor sum of the completely reduced quartic Hamiltonian

Structural symmetry and protein function.

Science.gov (United States)

Goodsell, D S; Olson, A J

2000-01-01

The majority of soluble and membrane-bound proteins in modern cells are symmetrical oligomeric complexes with two or more subunits. The evolutionary selection of symmetrical oligomeric complexes is driven by functional, genetic, and physicochemical needs. Large proteins are selected for specific morphological functions, such as formation of rings, containers, and filaments, and for cooperative functions, such as allosteric regulation and multivalent binding. Large proteins are also more stable against denaturation and have a reduced surface area exposed to solvent when compared with many individual, smaller proteins. Large proteins are constructed as oligomers for reasons of error control in synthesis, coding efficiency, and regulation of assembly. Symmetrical oligomers are favored because of stability and finite control of assembly. Several functions limit symmetry, such as interaction with DNA or membranes, and directional motion. Symmetry is broken or modified in many forms: quasisymmetry, in which identical subunits adopt similar but different conformations; pleomorphism, in which identical subunits form different complexes; pseudosymmetry, in which different molecules form approximately symmetrical complexes; and symmetry mismatch, in which oligomers of different symmetries interact along their respective symmetry axes. Asymmetry is also observed at several levels. Nearly all complexes show local asymmetry at the level of side chain conformation. Several complexes have reciprocating mechanisms in which the complex is asymmetric, but, over time, all subunits cycle through the same set of conformations. Global asymmetry is only rarely observed. Evolution of oligomeric complexes may favor the formation of dimers over complexes with higher cyclic symmetry, through a mechanism of prepositioned pairs of interacting residues. However, examples have been found for all of the crystallographic point groups, demonstrating that functional need can drive the evolution of

Intrinsic and extrinsic mortality reunited.

Science.gov (United States)

Koopman, Jacob J E; Wensink, Maarten J; Rozing, Maarten P; van Bodegom, David; Westendorp, Rudi G J

2015-07-01

Intrinsic and extrinsic mortality are often separated in order to understand and measure aging. Intrinsic mortality is assumed to be a result of aging and to increase over age, whereas extrinsic mortality is assumed to be a result of environmental hazards and be constant over age. However, allegedly intrinsic and extrinsic mortality have an exponentially increasing age pattern in common. Theories of aging assert that a combination of intrinsic and extrinsic stressors underlies the increasing risk of death. Epidemiological and biological data support that the control of intrinsic as well as extrinsic stressors can alleviate the aging process. We argue that aging and death can be better explained by the interaction of intrinsic and extrinsic stressors than by classifying mortality itself as being either intrinsic or extrinsic. Recognition of the tight interaction between intrinsic and extrinsic stressors in the causation of aging leads to the recognition that aging is not inevitable, but malleable through the environment. Copyright © 2015 Elsevier Inc. All rights reserved.

A new polar symmetry of huebnerite (MnWO{sub 4}) with ferrodistortive domains

Energy Technology Data Exchange (ETDEWEB)

Park, S.H., E-mail: sohyun.park@lmu.de [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Mihailova, B. [Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, 20146 Hamburg (Germany); Pedersen, B. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstraße 1, 85748 Garching (Germany); Paulmann, C. [Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, 20146 Hamburg (Germany); HASYLAB, DESY, Notkestr. 85, 22603 Hamburg (Germany); Behal, D. [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Lichtenbergstraße 1, 85748 Garching (Germany); Gattermann, U. [Sektion Kristallographie, Department für Geo-und Umweltwissenschaften, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 München (Germany); Hochleitner, R. [Mineralogische Staatssammlung München, Theresienstrasse 41, 80333 Munich (Germany)

2015-11-15

Large-size single-crystal samples of huebnerite natural multiferroic MnWO{sub 4} were analyzed by neutron and synchrotron X-ray single-crystal diffraction as well as by polarized Raman spectroscopy. Both neutron and X-ray diffraction analyzes reveal polar space-group symmetry P2 for the nuclear structure of huebnerite via the detection of weak reflections h0l (l=odd) forbidden for the gliding plane c. Renninger scans of the reflection 301 on the neutron single-crystal diffractometer RESI (FRM-II) could confirm the absence of the gliding plane c in both para- and antiferromagnetic states of huebnerite. The symmetry breaking could be explained by structure analyzes with neutron single crystal diffraction data at 293 K revealing that two Mn atoms in P2 are displaced independently along the b axis from their equilibrium position at a polar point site, C{sub 2} in P2/c. Micro X-ray diffraction and Raman-scattering mapping reveal a ferrodistortive domain texture in the room-temperature paramagnetic state of huebnerite, which is attributed to P2 domain formation through a proper ∼180° rotation about the reciprocal-space axis c*. - Graphical abstract: Schematic presentation of polar atomic shifts (arrows) in P2 from the respective equivalent sites (spheres) in P2/c at the boundary of two 180°-in-plane micro twins. - Highlights: • Neutron and X-ray diffraction analyzes reveal the polar symmetry P2 for MnWO{sub 4}. • Raman mapping shows ferrodistortive domains in its RT paramagnetic state. • These observations are explained by the hidden polar site C{sub 2} for Mn atoms.

Math grades and intrinsic motivation in elementary school: A longitudinal investigation of their association.

Science.gov (United States)

Weidinger, Anne F; Steinmayr, Ricarda; Spinath, Birgit

2017-06-01

It is often argued that the negative development of intrinsic motivation in elementary school strongly depends on the presence of school grades because grades represent extrinsic consequences and achievement feedback that are supposed to influence intrinsically motivated behaviour. However, only a few studies have tested this hypothesis. Therefore, we investigated the role of school grades in inter- and intra-individual changes in elementary school students' intrinsic motivation from when grades were first introduced until the end of elementary school, when students in Germany receive recommendations for a secondary school type on the basis of their prior performance in school. A sample of 542 German elementary school students (t 1 : M = 7.95 years, SD = 0.57) was followed for 2 years from the end of Grade 2 to the end of Grade 4. At seven measurement occasions, children's math grades and their domain-specific intrinsic motivation were assessed. Latent growth curve models showed differences in trajectories of intrinsic motivation across students rather than uniform development. Moreover, students' trajectories of grades and intrinsic motivation were only weakly associated. A latent cross-lagged model revealed that reciprocal effects between the two constructs over time were small at best. Contrary to theoretical considerations, our results indicate that negative performance feedback in the form of grades does not necessarily lead to a decrease in intrinsic motivation. This calls into question the common opinion that a perception of being less competent, as reflected by poor grades, is responsible for weakening students' intrinsic motivation. © 2017 The British Psychological Society.

Gapless Symmetry-Protected Topological Order

Directory of Open Access Journals (Sweden)

Thomas Scaffidi

2017-11-01

Full Text Available We introduce exactly solvable gapless quantum systems in d dimensions that support symmetry-protected topological (SPT edge modes. Our construction leads to long-range entangled, critical points or phases that can be interpreted as critical condensates of domain walls “decorated” with dimension (d-1 SPT systems. Using a combination of field theory and exact lattice results, we argue that such gapless SPT systems have symmetry-protected topological edge modes that can be either gapless or symmetry broken, leading to unusual surface critical properties. Despite the absence of a bulk gap, these edge modes are robust against arbitrary symmetry-preserving local perturbations near the edges. In two dimensions, we construct wave functions that can also be interpreted as unusual quantum critical points with diffusive scaling in the bulk but ballistic edge dynamics.

Studies on phenomenological hadron models with chiral symmetry

International Nuclear Information System (INIS)

Rathske, E.

1991-12-01

In this report we consider, in the context of phenomenological models for hadrons, several aspects of Skyrme-type and hybrid bag models. In the first of the two central parts we discuss two qualitatively different generalizations of the minimal SU(2) Skyrme model. One of these consists in adding to the Lagrangian density a symmetric term of fourth order in the field derivatives. Its consequences are determined for solutions and observables by analytical and numerical investigations. In the other we propose a contribution for explicit isospin symmetry breaking in the mesonic as well as the baryonic sector. Together with the standard nonlinear σ-model term it allows for exact time-dependent classical soliton solutions. Their quantization leads to a quantitative connection between the hadronic isospin mass differenced of pions and nucleons. The second main part of this report is devoted to the generalization of SU(2) bag models under the aspect of chiral symmetry. We first show that the construction of appropriate surface terms in the Lagrangian density necessitates the introduction of dynamical bosonic degrees of freedom. This allows for a variety of bag scenarios (including the 'endopionic' bag). We then consider explicit isospin symmetry breaking for hybrid bag models with a nonlinear mesonic sector. An intimate relationship is revealed between the effects of a quark mass difference and the time-dependent bosonic solutions found for the purely mesonic case. It is reflected in a nontrivial interdependence between quark and meson masses, bag radius and chiral angle. We provide an especially extensive list of references for the topics discussed in this report. (orig.) [de

Symmetry and symmetry breaking in quantum mechanics; Symetrie et brisure de symetrie en mechanique quantique

Energy Technology Data Exchange (ETDEWEB)

Chomaz, Philippe [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)

1998-12-31

In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation 17 refs., 16 figs.

Partner symmetries of the complex Monge-Ampere equation yield hyper-Kaehler metrics without continuous symmetries

International Nuclear Information System (INIS)

Malykh, A A; Nutku, Y; Sheftel, M B

2003-01-01

We extend the Mason-Newman Lax pair for the elliptic complex Monge-Ampere equation so that this equation itself emerges as an algebraic consequence. We regard the function in the extended Lax equations as a complex potential. Their differential compatibility condition coincides with the determining equation for the symmetries of the complex Monge-Ampere equation. We shall identify the real and imaginary parts of the potential, which we call partner symmetries, with the translational and dilatational symmetry characteristics, respectively. Then we choose the dilatational symmetry characteristic as the new unknown replacing the Kaehler potential. This directly leads to a Legendre transformation. Studying the integrability conditions of the Legendre-transformed system we arrive at a set of linear equations satisfied by a single real potential. This enables us to construct non-invariant solutions of the Legendre transform of the complex Monge-Ampere equation. Using these solutions we obtained explicit Legendre-transformed hyper-Kaehler metrics with a anti-self-dual Riemann curvature 2-form that admit no Killing vectors. They satisfy the Einstein field equations with Euclidean signature. We give the detailed derivation of the solution announced earlier and present a new solution with an added parameter. We compare our method of partner symmetries for finding non-invariant solutions to that of Dunajski and Mason who use 'hidden' symmetries for the same purpose

The symmetry of the Hubbard model

International Nuclear Information System (INIS)

Grosse, H.

1988-01-01

The spectrum of the Hubbard model shows permanent degeneracy of levels with different symmetry, if one considers only symmetry operators independent of the coupling constant. This suggests the existence of symmetry operators which depend on the coupling constant. We find these highly nontrivial operators and show that they explain the degeneracies in the energy spectrum. 5 refs. (Author)

Dynamical symmetry breaking in barium isotopes

International Nuclear Information System (INIS)

Rawat, Bir Singh; Chattopadhyay, P.K.

1997-01-01

The isotopes of Xe with mass numbers 124, 126, 128, 130 and the isotopes of barium with mass numbers 128, 130, 132, 134 were shown to correspond to the O(6) dynamical symmetry of IBM. In the investigation of the dynamical symmetry breaking in this region, the barium isotopes for departures from O(6) symmetry have been studied

Intrinsic-density functionals

International Nuclear Information System (INIS)

Engel, J.

2007-01-01

The Hohenberg-Kohn theorem and Kohn-Sham procedure are extended to functionals of the localized intrinsic density of a self-bound system such as a nucleus. After defining the intrinsic-density functional, we modify the usual Kohn-Sham procedure slightly to evaluate the mean-field approximation to the functional, and carefully describe the construction of the leading corrections for a system of fermions in one dimension with a spin-degeneracy equal to the number of particles N. Despite the fact that the corrections are complicated and nonlocal, we are able to construct a local Skyrme-like intrinsic-density functional that, while different from the exact functional, shares with it a minimum value equal to the exact ground-state energy at the exact ground-state intrinsic density, to next-to-leading order in 1/N. We briefly discuss implications for real Skyrme functionals

Astroparticle tests of Lorentz symmetry

Energy Technology Data Exchange (ETDEWEB)

Diaz, Jorge [Karlsruhe Institute of Technology, Karlsruhe (Germany)

2016-07-01

Lorentz symmetry is a cornerstone of modern physics. As the spacetime symmetry of special relativity, Lorentz invariance is a basic component of the standard model of particle physics and general relativity, which to date constitute our most successful descriptions of nature. Deviations from exact symmetry would radically change our view of the universe and current experiments allow us to test the validity of this assumption. In this talk, I describe effects of Lorentz violation in cosmic rays and gamma rays that can be studied in current observatories.

Dynamics symmetries of Hamiltonian system on time scales

Energy Technology Data Exchange (ETDEWEB)

Peng, Keke, E-mail: pengkeke88@126.com; Luo, Yiping, E-mail: zjstulyp@126.com [Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

2014-04-15

In this paper, the dynamics symmetries of Hamiltonian system on time scales are studied. We study the symmetries and quantities based on the calculation of variation and Lie transformation group. Particular focus lies in: the Noether symmetry leads to the Noether conserved quantity and the Lie symmetry leads to the Noether conserved quantity if the infinitesimal transformations satisfy the structure equation. As the new application of result, at end of the article, we give a simple example of Noether symmetry and Lie symmetry on time scales.

Symmetry and symmetry breaking in modern physics

International Nuclear Information System (INIS)

Barone, M; Theophilou, A K

2008-01-01

In modern physics, the theory of symmetry, i.e. group theory, is a basic tool for understanding and formulating the fundamental principles of Physics, like Relativity, Quantum Mechanics and Particle Physics. In this work we focus on the relation between Mathematics, Physics and objective reality

Symmetry and inflation

International Nuclear Information System (INIS)

Chimento, Luis P.

2002-01-01

We find the group of symmetry transformations under which the Einstein equations for the spatially flat Friedmann-Robertson-Walker universe are form invariant. They relate the energy density and the pressure of the fluid to the expansion rate. We show that inflation can be obtained from nonaccelerated scenarios by a symmetry transformation. We derive the transformation rule for the spectrum and spectral index of the curvature perturbations. Finally, the group is extended to investigate inflation in the anisotropic Bianchi type-I spacetime and the brane-world cosmology

wACSF—Weighted atom-centered symmetry functions as descriptors in machine learning potentials

Science.gov (United States)

Gastegger, M.; Schwiedrzik, L.; Bittermann, M.; Berzsenyi, F.; Marquetand, P.

2018-06-01

We introduce weighted atom-centered symmetry functions (wACSFs) as descriptors of a chemical system's geometry for use in the prediction of chemical properties such as enthalpies or potential energies via machine learning. The wACSFs are based on conventional atom-centered symmetry functions (ACSFs) but overcome the undesirable scaling of the latter with an increasing number of different elements in a chemical system. The performance of these two descriptors is compared using them as inputs in high-dimensional neural network potentials (HDNNPs), employing the molecular structures and associated enthalpies of the 133 855 molecules containing up to five different elements reported in the QM9 database as reference data. A substantially smaller number of wACSFs than ACSFs is needed to obtain a comparable spatial resolution of the molecular structures. At the same time, this smaller set of wACSFs leads to a significantly better generalization performance in the machine learning potential than the large set of conventional ACSFs. Furthermore, we show that the intrinsic parameters of the descriptors can in principle be optimized with a genetic algorithm in a highly automated manner. For the wACSFs employed here, we find however that using a simple empirical parametrization scheme is sufficient in order to obtain HDNNPs with high accuracy.

Neutrino masses and spontaneously broken flavor symmetries

International Nuclear Information System (INIS)

Staudt, Christian

2014-01-01

We study the phenomenology of supersymmetric flavor models. We show how the predictions of models based on spontaneously broken non-Abelian discrete flavor symmetries are altered when we include so-called Kaehler corrections. Furthermore, we discuss anomaly-free discrete R symmetries which are compatible with SU(5) unification. We find a set of symmetries compatible with suppressed Dirac neutrino masses and a unique symmetry consistent with the Weinberg operator. We also study a pseudo-anomalous U(1) R symmetry which explains the fermion mass hierarchies and, when amended with additional singlet fields, ameliorates the fine-tuning problem.

Extracting intrinsic functional networks with feature-based group independent component analysis.

Science.gov (United States)

Calhoun, Vince D; Allen, Elena

2013-04-01

There is increasing use of functional imaging data to understand the macro-connectome of the human brain. Of particular interest is the structure and function of intrinsic networks (regions exhibiting temporally coherent activity both at rest and while a task is being performed), which account for a significant portion of the variance in functional MRI data. While networks are typically estimated based on the temporal similarity between regions (based on temporal correlation, clustering methods, or independent component analysis [ICA]), some recent work has suggested that these intrinsic networks can be extracted from the inter-subject covariation among highly distilled features, such as amplitude maps reflecting regions modulated by a task or even coordinates extracted from large meta analytic studies. In this paper our goal was to explicitly compare the networks obtained from a first-level ICA (ICA on the spatio-temporal functional magnetic resonance imaging (fMRI) data) to those from a second-level ICA (i.e., ICA on computed features rather than on the first-level fMRI data). Convergent results from simulations, task-fMRI data, and rest-fMRI data show that the second-level analysis is slightly noisier than the first-level analysis but yields strikingly similar patterns of intrinsic networks (spatial correlations as high as 0.85 for task data and 0.65 for rest data, well above the empirical null) and also preserves the relationship of these networks with other variables such as age (for example, default mode network regions tended to show decreased low frequency power for first-level analyses and decreased loading parameters for second-level analyses). In addition, the best-estimated second-level results are those which are the most strongly reflected in the input feature. In summary, the use of feature-based ICA appears to be a valid tool for extracting intrinsic networks. We believe it will become a useful and important approach in the study of the macro

Comment on "Polarized window for left-right symmetry and a right-handed neutrino at the Large Hadron-Electron Collider"

Science.gov (United States)

Queiroz, Farinaldo S.

2016-06-01

Reference [1 S. Mondal and S. K. Rai, Phys. Rev. D 93, 011702 (2016).] recently argued that the projected Large Hadron Electron Collider (LHeC) presents a unique opportunity to discover a left-right symmetry since the LHeC has availability for polarized electrons. In particular, the authors apply some basic pT cuts on the jets and claim that the on-shell production of right-handed neutrinos at the LHeC, which violates lepton number in two units, has practically no standard model background and, therefore, that the right-handed nature of WR interactions that are intrinsic to left-right symmetric models can be confirmed by using colliding beams consisting of an 80% polarized electron and a 7 TeV proton. In this Comment, we show that their findings, as presented, have vastly underestimated the SM background which prevents a Left-Right symmetry signal from being seen at the LHeC.

Symmetries in physics and harmonics

International Nuclear Information System (INIS)

Kolk, D.

2006-01-01

In this book the symmetries of elementary particles are described in relation to the rules of harmonics in music. The selection rules are described in connections with harmonic intervals. Also symmetry breaking is considered in this framework. (HSI)

Azimuthal Seismic Amplitude Variation with Offset and Azimuth Inversion in Weakly Anisotropic Media with Orthorhombic Symmetry

Science.gov (United States)

Pan, Xinpeng; Zhang, Guangzhi; Yin, Xingyao

2018-01-01

Seismic amplitude variation with offset and azimuth (AVOaz) inversion is well known as a popular and pragmatic tool utilized to estimate fracture parameters. A single set of vertical fractures aligned along a preferred horizontal direction embedded in a horizontally layered medium can be considered as an effective long-wavelength orthorhombic medium. Estimation of Thomsen's weak-anisotropy (WA) parameters and fracture weaknesses plays an important role in characterizing the orthorhombic anisotropy in a weakly anisotropic medium. Our goal is to demonstrate an orthorhombic anisotropic AVOaz inversion approach to describe the orthorhombic anisotropy utilizing the observable wide-azimuth seismic reflection data in a fractured reservoir with the assumption of orthorhombic symmetry. Combining Thomsen's WA theory and linear-slip model, we first derive a perturbation in stiffness matrix of a weakly anisotropic medium with orthorhombic symmetry under the assumption of small WA parameters and fracture weaknesses. Using the perturbation matrix and scattering function, we then derive an expression for linearized PP-wave reflection coefficient in terms of P- and S-wave moduli, density, Thomsen's WA parameters, and fracture weaknesses in such an orthorhombic medium, which avoids the complicated nonlinear relationship between the orthorhombic anisotropy and azimuthal seismic reflection data. Incorporating azimuthal seismic data and Bayesian inversion theory, the maximum a posteriori solutions of Thomsen's WA parameters and fracture weaknesses in a weakly anisotropic medium with orthorhombic symmetry are reasonably estimated with the constraints of Cauchy a priori probability distribution and smooth initial models of model parameters to enhance the inversion resolution and the nonlinear iteratively reweighted least squares strategy. The synthetic examples containing a moderate noise demonstrate the feasibility of the derived orthorhombic anisotropic AVOaz inversion method, and the

Geometrical spin symmetry and spin

International Nuclear Information System (INIS)

Pestov, I. B.

2011-01-01

Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

Symmetry of quantum molecular dynamics

International Nuclear Information System (INIS)

Burenin, A.V.

2002-01-01

The paper reviews the current state-of-art in describing quantum molecular dynamics based on symmetry principles alone. This qualitative approach is of particular interest as the only method currently available for a broad and topical class of problems in the internal dynamics of molecules. Besides, a molecule is a physical system whose collective internal motions are geometrically structured, and its perturbation theory description requires a symmetry analysis of this structure. The nature of the geometrical symmetry groups crucial for the closed formulation of the qualitative approach is discussed [ru

[Medical professionals on the subject of their core values: the importance of practice-based stories and intrinsic motivation].

Science.gov (United States)

Witman, Yolande; van den Kerkhof, Peter C M; Braat, Didi D M

2013-01-01

In the current system for guaranteeing quality of care, emphasis is placed firmly on external control of professionals. We looked for a way to appeal to the intrinsic motivation of medical professionals and to discover what they mean by 'good work'. This was achieved with the aid of reflective sessions using the toolkit 'Good Work': in four sessions three different groups of medical professionals (medical department chairs, residents and interns) from a Dutch university hospital reflected on the topics 'excellence', 'moral responsibility' and 'personal engagement'. The participants exchanged practice-based stories during the sessions. The most important theme was moral responsibility, with its accompanying dilemmas. The sessions gave rise to feelings of mutual acknowledgement, recognition, inspiration and motivation. Sharing meaningful practice-based stories can be considered as a 'moment of learning', strengthening professional identity and stimulating intrinsic motivation. More space for this form of reflection might restore the balance with external control systems.

Current status and future prospect of space and time reversal symmetry violation on low energy neutron reactions

International Nuclear Information System (INIS)

Masuda, Yasuhiro

1993-01-01

In this report, the papers on symmetry violation under space reflection and time reversal and neutron spin, neutron spin rotation and P-violation, parity nonconservation in neutron capture reaction, some advantage of the search for CP-violation in neutron scattering, dynamic polarization of 139 La target, alexandrite laser for optical pumping, polarized 3 He system for T- and P-violation neutron experiments, control of neutron spin in T-violation neutron experiment, symmetry regarding time and space and angular distribution and angular correlation of radiation and particle beams, T-violation due to low temperature nuclear polarization and axion exploration using nuclear transition are collected. (K.I.)

On reflection algebras and twisted Yangians

International Nuclear Information System (INIS)

Doikou, Anastasia

2005-01-01

It is well known that integrable models associated to rational R matrices give rise to certain non-Abelian symmetries known as Yangians. Analogously boundary symmetries arise when general but still integrable boundary conditions are implemented, as originally argued by Delius, Mackay, and Short from the field theory point of view, in the context of the principal chiral model on the half-line. In the present study we deal with a discrete quantum mechanical system with boundaries, that is the N site gl(n) open quantum spin chain. In particular, the open spin chain with two distinct types of boundary condition known as soliton preserving and soliton nonpreserving is considered. For both types of boundaries we present a unified framework for deriving the corresponding boundary nonlocal charges directly at the quantum level. The nonlocal charges are simply coproduct realizations of particular boundary quantum algebras called boundary or twisted Yangians, depending on the choice of boundary conditions. Finally, with the help of linear intertwining relations between the solutions of the reflection equation and the generators of the boundary or twisted Yangians we are able to exhibit the exact symmetry of the open spin chain, namely we show that a number of the boundary nonlocal charges are in fact conserved quantities

Local symmetry breaking and spin–phonon coupling in SmCrO3 orthochromite

International Nuclear Information System (INIS)

El Amrani, M.; Zaghrioui, M.; Ta Phuoc, V.; Gervais, F.; Massa, Néstor E.

2014-01-01

Raman scattering and infrared reflectivity performed on polycrystalline SmCrO 3 support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T N . Such a behavior is explained by spin–phonon coupling in this compound. Furthermore, temperature dependence of the infrared spectra has demonstrated important changes compared to the Raman spectra, suggesting strong structural modifications due to the cation displacements rather to those of the oxygen ions. Our results reveal that polar distortions originating in local symmetry breaking, i.e. local non-centrosymmetry, resulting in Cr off-centring. - Highlights: • We investigated Raman and infrared phonon modes of SmCrO 3 versus temperature. • Results reveal strong influence of the antiferromagnetic order on phonon modes. • Temperature dependence of the infrared spectra shows strong structural modifications suggesting local symmetry breaking

The priority of internal symmetries in particle physics

Science.gov (United States)

Kantorovich, Aharon

2003-12-01

In this paper, I try to decipher the role of internal symmetries in the ontological maze of particle physics. The relationship between internal symmetries and laws of nature is discussed within the framework of ;Platonic realism.; The notion of physical ;structure; is introduced as representing a deeper ontological layer behind the observable world. I argue that an internal symmetry is a structure encompassing laws of nature. The application of internal symmetry groups to particle physics came about in two revolutionary steps. The first was the introduction of the internal symmetries of hadrons in the early 1960s. These global and approximate symmetries served as means of bypassing the dynamics. I argue that the realist could interpret these symmetries as ontologically prior to the hadrons. The second step was the gauge revolution in the 1970s, where symmetries became local and exact and were integrated with the dynamics. I argue that the symmetries of the second generation are fundamental in the following two respects: (1) According to the so-called ;gauge argument,; gauge symmetry dictates the existence of gauge bosons, which determine the nature of the forces. This view, which has been recently criticized by some philosophers, is widely accepted in particle physics at least as a heuristic principle. (2) In view of grand unified theories, the new symmetries can be interpreted as ontologically prior to baryon matter.

Facial attractiveness, symmetry and cues of good genes.

Science.gov (United States)

Scheib, J E; Gangestad, S W; Thornhill, R

1999-09-22

Cues of phenotypic condition should be among those used by women in their choice of mates. One marker of better phenotypic condition is thought to be symmetrical bilateral body and facial features. However, it is not clear whether women use symmetry as the primary cue in assessing the phenotypic quality of potential mates or whether symmetry is correlated with other facial markers affecting physical attractiveness. Using photographs of men's faces, for which facial symmetry had been measured, we found a relationship between women's attractiveness ratings of these faces and symmetry, but the subjects could not rate facial symmetry accurately. Moreover, the relationship between facial attractiveness and symmetry was still observed, even when symmetry cues were removed by presenting only the left or right half of faces. These results suggest that attractive features other than symmetry can be used to assess phenotypic condition. We identified one such cue, facial masculinity (cheek-bone prominence and a relatively longer lower face), which was related to both symmetry and full- and half-face attractiveness.

Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge

International Nuclear Information System (INIS)

Dong, L. F.; Xiao, H.; Fan, W. L.; Yin, Z. Q.; Zhao, H. T.

2010-01-01

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.

On the origin of neutrino flavour symmetry

International Nuclear Information System (INIS)

King, Stephen F.; Luhn, Christoph

2009-01-01

We study classes of models which are based on some discrete family symmetry which is completely broken such that the observed neutrino flavour symmetry emerges indirectly as an accidental symmetry. For such 'indirect' models we discuss the D-term flavon vacuum alignments which are required for such an accidental flavour symmetry consistent with tri-bimaximal lepton mixing to emerge. We identify large classes of suitable discrete family symmetries, namely the Δ(3n 2 ) and Δ(6n 2 ) groups, together with other examples such as Z 7 x Z 3 . In such indirect models the implementation of the type I see-saw mechanism is straightforward using constrained sequential dominance. However the accidental neutrino flavour symmetry may be easily violated, for example leading to a large reactor angle, while maintaining accurately the tri-bimaximal solar and atmospheric predictions.

Probing symmetry and symmetry breaking in resonant soft-x-ray fluorescence spectra of molecules

Energy Technology Data Exchange (ETDEWEB)

Glans, P.; Gunnelin, K.; Guo, J. [Uppsala Univ. (Sweden)] [and others

1997-04-01

Conventional non-resonant soft X-ray emission brings about information about electronic structure through its symmetry and polarization selectivity, the character of which is governed by simple dipole rules. For centro-symmetric molecules with the emitting atom at the inversion center these rules lead to selective emission through the required parity change. For the more common classes of molecules which have lower symmetry or for systems with degenerate core orbitals (delocalized over identical sites), it is merely the local symmetry selectivity that provides a probe of the local atomic orbital contribution to the molecular orbital. For instance, in X-ray spectra of first row species the intensities essentially map the p-density at each particular atomic site, and, in a molecular orbital picture, the contribution of the local p-type atomic orbitals in the LCAO description of the molecular orbitals. The situation is different for resonant X-ray fluorescence spectra. Here strict parity and symmetry selectivity gives rise to a strong frequency dependence for all molecules with an element of symmetry. In addition to symmetry selectivity the strong frequency dependence of resonant X-ray emission is caused by the interplay between the shape of a narrow X-ray excitation energy function and the lifetime and vibrational broadenings of the resonantly excited core states. This interplay leads to various observable effects, such as linear dispersion, resonance narrowing and emission line (Stokes) doubling. Also from the point of view of polarization selectivity, the resonantly excited X-ray spectra are much more informative than the corresponding non-resonant spectra. Examples are presented for nitrogen, oxygen, and carbon dioxide molecules.

Stringy origin of non-Abelian discrete flavor symmetries

International Nuclear Information System (INIS)

Kobayashi, Tatsuo; Nilles, Hans Peter; Ploeger, Felix; Raby, Stuart; Ratz, Michael

2007-01-01

We study the origin of non-Abelian discrete flavor symmetries in superstring theory. We classify all possible non-Abelian discrete flavor symmetries which can appear in heterotic orbifold models. These symmetries include D 4 and Δ(54). We find that the symmetries of the couplings are always larger than the symmetries of the compact space. This is because they are a consequence of the geometry of the orbifold combined with the space group selection rules of the string. We also study possible breaking patterns. Our analysis yields a simple geometric understanding of the realization of non-Abelian flavor symmetries

Nonlinear (super)symmetries and amplitudes

Energy Technology Data Exchange (ETDEWEB)

Kallosh, Renata [Physics Department, Stanford University,382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

2017-03-07

There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E{sub 7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N≥5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.

Applications of hidden symmetries to black hole physics

International Nuclear Information System (INIS)

Frolov, Valeri

2011-01-01

This work is a brief review of applications of hidden symmetries to black hole physics. Symmetry is one of the most important concepts of the science. In physics and mathematics the symmetry allows one to simplify a problem, and often to make it solvable. According to the Noether theorem symmetries are responsible for conservation laws. Besides evident (explicit) spacetime symmetries, responsible for conservation of energy, momentum, and angular momentum of a system, there also exist what is called hidden symmetries, which are connected with higher order in momentum integrals of motion. A remarkable fact is that black holes in four and higher dimensions always possess a set ('tower') of explicit and hidden symmetries which make the equations of motion of particles and light completely integrable. The paper gives a general review of the recently obtained results. The main focus is on understanding why at all black holes have something (symmetry) to hide.

Gauge origin of discrete flavor symmetries in heterotic orbifolds

Directory of Open Access Journals (Sweden)

Florian Beye

2014-09-01

Full Text Available We show that non-Abelian discrete symmetries in orbifold string models have a gauge origin. This can be understood when looking at the vicinity of a symmetry enhanced point in moduli space. At such an enhanced point, orbifold fixed points are characterized by an enhanced gauge symmetry. This gauge symmetry can be broken to a discrete subgroup by a nontrivial vacuum expectation value of the Kähler modulus T. Using this mechanism it is shown that the Δ(54 non-Abelian discrete symmetry group originates from a SU(3 gauge symmetry, whereas the D4 symmetry group is obtained from a SU(2 gauge symmetry.

R-symmetries from the orbifolded heterotic string

International Nuclear Information System (INIS)

Schmitz, Matthias

2014-08-01

We examine the geometric origin of discrete R-symmetries in heterotic orbifold compactifications. By analysing the symmetries of the worldsheet instanton solutions and the underlying geometry, we obtain a scheme that allows us to systematically explore the R-symmetries arising in these compactifications. Applying this scheme to a classification of orbifold geometries, we are able to find all R-symmetries of heterotic orbifolds with Abelian point groups. We show that in the vast majority of cases, the R-symmetries found satisfy anomaly universality constraints, as required in heterotic orbifolds. Then we examine the implications of the presence of these R-symmetries on a class of phenomenologically attractive orbifold compactifications known as the heterotic mini-landscape. We use the technique of Hilbert bases in order to analyse the properties of a vacuum configuration. We find that phenomenologically viable models remain and the main attractive features of the mini-landscape are unaltered.

Symmetry analysis in parametrisation of complex systems

International Nuclear Information System (INIS)

Sikora, W; Malinowski, J

2010-01-01

The symmetry analysis method based on the theory of group representations is used for description of complex systems and their behavior in this work. The first trial of using the symmetry analysis in modeling of behavior of complex social system is presented. The evacuation of large building scenarios are discussed as transition from chaotic to ordered states, described as movements of individuals according to fields of displacements, calculated correspondingly to given scenario. The symmetry of the evacuation space is taken into account in calculation of displacements field - the displacements related to every point of this space are presented in the coordinate frame in the best way adapted to given symmetry space group, which is the set of basic vectors of irreducible representation of given symmetry group. The results got with using the symmetry consideration are compared with corresponding results calculated under assumption of shortest way to exits (Voronoi assumption).

Symmetry analysis in parametrisation of complex systems

Energy Technology Data Exchange (ETDEWEB)

Sikora, W; Malinowski, J, E-mail: sikora@novell.ftj.agh.edu.p [Faculty of Physics and Applied Computer Science, AGH - University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland)

2010-03-01

The symmetry analysis method based on the theory of group representations is used for description of complex systems and their behavior in this work. The first trial of using the symmetry analysis in modeling of behavior of complex social system is presented. The evacuation of large building scenarios are discussed as transition from chaotic to ordered states, described as movements of individuals according to fields of displacements, calculated correspondingly to given scenario. The symmetry of the evacuation space is taken into account in calculation of displacements field - the displacements related to every point of this space are presented in the coordinate frame in the best way adapted to given symmetry space group, which is the set of basic vectors of irreducible representation of given symmetry group. The results got with using the symmetry consideration are compared with corresponding results calculated under assumption of shortest way to exits (Voronoi assumption).

Anomalous Symmetry Fractionalization and Surface Topological Order

Directory of Open Access Journals (Sweden)

Xie Chen

2015-10-01

Full Text Available In addition to possessing fractional statistics, anyon excitations of a 2D topologically ordered state can realize symmetry in distinct ways, leading to a variety of symmetry-enriched topological (SET phases. While the symmetry fractionalization must be consistent with the fusion and braiding rules of the anyons, not all ostensibly consistent symmetry fractionalizations can be realized in 2D systems. Instead, certain “anomalous” SETs can only occur on the surface of a 3D symmetry-protected topological (SPT phase. In this paper, we describe a procedure for determining whether a SET of a discrete, on-site, unitary symmetry group G is anomalous or not. The basic idea is to gauge the symmetry and expose the anomaly as an obstruction to a consistent topological theory combining both the original anyons and the gauge fluxes. Utilizing a result of Etingof, Nikshych, and Ostrik, we point out that a class of obstructions is captured by the fourth cohomology group H^{4}(G,U(1, which also precisely labels the set of 3D SPT phases, with symmetry group G. An explicit procedure for calculating the cohomology data from a SET is given, with the corresponding physical intuition explained. We thus establish a general bulk-boundary correspondence between the anomalous SET and the 3D bulk SPT whose surface termination realizes it. We illustrate this idea using the chiral spin liquid [U(1_{2}] topological order with a reduced symmetry Z_{2}×Z_{2}⊂SO(3, which can act on the semion quasiparticle in an anomalous way. We construct exactly solved 3D SPT models realizing the anomalous surface terminations and demonstrate that they are nontrivial by computing three-loop braiding statistics. Possible extensions to antiunitary symmetries are also discussed.

Translational spacetime symmetries in gravitational theories

International Nuclear Information System (INIS)

Petti, R J

2006-01-01

How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle and (3) using the affine connection and the zero section to define an 'associated solder form', whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however, it violates translational equivariance/gauge symmetry. This is the natural geometric framework for Einstein-Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry

Bilateral symmetry analysis of breast MRI

International Nuclear Information System (INIS)

Alterson, Robert; Plewes, Donald B

2003-01-01

Mammographic interpretation often uses symmetry between left and right breasts to indicate the site of potential tumour masses. This approach has not been applied to breast images obtained from MRI. We present an automatic technique for breast symmetry detection based on feature extraction techniques which does not require any efforts to co-register breast MRI data. The approach applies computer-vision techniques to detect natural biological symmetries in breast MR scans based on three objective measures of similarity: multiresolution non-orthogonal wavelet representation, three-dimensional intensity distributions and co-occurrence matrices. Statistical distributions that are invariant to feature localization are computed for each of the extracted image features. These distributions are later compared against each other to account for perceptual similarity. Studies based on 51 normal MRI scans of randomly selected patients showed that the sensitivity of symmetry detection rate approached 94%. The symmetry analysis procedure presented in this paper can be applied as an aid in detecting breast tissue changes arising from disease

Ermakov's Superintegrable Toy and Nonlocal Symmetries

Science.gov (United States)

Leach, P. G. L.; Karasu Kalkanli, A.; Nucci, M. C.; Andriopoulos, K.

2005-11-01

We investigate the symmetry properties of a pair of Ermakov equations. The system is superintegrable and yet possesses only three Lie point symmetries with the algebra sl(2, R). The number of point symmetries is insufficient and the algebra unsuitable for the complete specification of the system. We use the method of reduction of order to reduce the nonlinear fourth-order system to a third-order system comprising a linear second-order equation and a conservation law. We obtain the representation of the complete symmetry group from this system. Four of the required symmetries are nonlocal and the algebra is the direct sum of a one-dimensional Abelian algebra with the semidirect sum of a two-dimensional solvable algebra with a two-dimensional Abelian algebra. The problem illustrates the difficulties which can arise in very elementary systems. Our treatment demonstrates the existence of possible routes to overcome these problems in a systematic fashion.

Ermakov's Superintegrable Toy and Nonlocal Symmetries

Directory of Open Access Journals (Sweden)

P.G.L. Leach

2005-11-01

Full Text Available We investigate the symmetry properties of a pair of Ermakov equations. The system is superintegrable and yet possesses only three Lie point symmetries with the algebra sl(2, R. The number of point symmetries is insufficient and the algebra unsuitable for the complete specification of the system. We use the method of reduction of order to reduce the nonlinear fourth-order system to a third-order system comprising a linear second-order equation and a conservation law. We obtain the representation of the complete symmetry group from this system. Four of the required symmetries are nonlocal and the algebra is the direct sum of a one-dimensional Abelian algebra with the semidirect sum of a two-dimensional solvable algebra with a two-dimensional Abelian algebra. The problem illustrates the difficulties which can arise in very elementary systems. Our treatment demonstrates the existence of possible routes to overcome these problems in a systematic fashion.

Translational spacetime symmetries in gravitational theories

Energy Technology Data Exchange (ETDEWEB)

Petti, R J [MathWorks, Inc., 3 Apple Hill Drive, Natick, MA 01760 (United States)

2006-02-07

How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle and (3) using the affine connection and the zero section to define an 'associated solder form', whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however, it violates translational equivariance/gauge symmetry. This is the natural geometric framework for Einstein-Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry.

Symmetry in social exchange and health

Science.gov (United States)

Siegrist, Johannes

2005-10-01

Symmetry is a relevant concept in sociological theories of exchange. It is rooted in the evolutionary old norm of social reciprocity and is particularly important in social contracts. Symmetry breaking through violation of the norm of reciprocity generates strain in micro-social systems and, above all, in victims of non-symmetric exchange. In this contribution, adverse healthconsequences of symmetry breaking in contractual social exchange are analysed, with a main focus on the employment contract. Scientific evidence is derived from prospective epidemiological studies testing the model of effort-reward imbalance at work. Overall, a twofold elevated risk of incident disease is observed in employed men and women who are exposed to non-symmetric exchange. Health risks include coronary heart disease, depression and alcohol dependence, among others. Preliminary results suggest similar effects on health produced by symmetry breaking in other types of social relationships (e.g. partnership, parental roles). These findings underline the importance of symmetry in contractual social exchange for health and well-being.

Discovering Symmetry in Everyday Environments: A Creative Approach to Teaching Symmetry and Point Groups

Science.gov (United States)

Fuchigami, Kei; Schrandt, Matthew; Miessler, Gary L.

2016-01-01

A hands-on symmetry project is proposed as an innovative way of teaching point groups to undergraduate chemistry students. Traditionally, courses teaching symmetry require students to identify the point group of a given object. This project asks the reverse: students are instructed to identify an object that matches each point group. Doing so…

Scale symmetry and virial theorem

International Nuclear Information System (INIS)

Westenholz, C. von

1978-01-01

Scale symmetry (or dilatation invariance) is discussed in terms of Noether's Theorem expressed in terms of a symmetry group action on phase space endowed with a symplectic structure. The conventional conceptual approach expressing invariance of some Hamiltonian under scale transformations is re-expressed in alternate form by infinitesimal automorphisms of the given symplectic structure. That is, the vector field representing scale transformations leaves the symplectic structure invariant. In this model, the conserved quantity or constant of motion related to scale symmetry is the virial. It is shown that the conventional virial theorem can be derived within this framework

The detrimental effects of extrinsic reinforcement on “Intrinsic motivation”

Science.gov (United States)

Dickinson, Alyce M.

1989-01-01

Extrinsic consequences have been criticized on the grounds that they decrease intrinsic motivation or internally initiated behavior. Two popular rationales for this criticism, Lepper's overjustification hypothesis (1981) and Deci's motivational theory (Deci & Ryan, 1985), are reviewed and the criticism is then redefined behaviorally. “Intrinsically controlled” behavior is defined as behavior maintained by response-produced reinforcers, and the question concerning extrinsic consequences is thus restated as follows: When behavior is maintained by response-produced stimuli, does extrinsic reinforcement decrease the reinforcing value of those stimuli? The empirical support for this detrimental effect is summarized briefly, and several possible explanations for the phenomenon are offered. Research results that reflect on the effect's generality and social significance are discussed next, with the conclusion that the effect is transient and not likely to occur at all if extrinsic rewards are reinforcing, noncompetitive, based on reasonable performance standards, and delivered repetitively. PMID:22478013

Additional symmetries of supersymmetric KP hierarchies

International Nuclear Information System (INIS)

Stanciu, S.

1994-01-01

We investigate the additional symmetries of several supersymmetric KP hierarchies: the SKP hierarchy of Manin and Radul, the SKP 2 hierarchy, and the Jacobian SKP hierarchy. In all three cases we find that the algebra of symmetries is isomorphic to the algebra of superdifferential operators, or equivalently SW 1+∞ . These results seem to suggest that despite their realization depending on the dynamics, the additional symmetries are kinematical in nature. (orig.)

Approximate Noether symmetries and collineations for regular perturbative Lagrangians

Science.gov (United States)

Paliathanasis, Andronikos; Jamal, Sameerah

2018-01-01

Regular perturbative Lagrangians that admit approximate Noether symmetries and approximate conservation laws are studied. Specifically, we investigate the connection between approximate Noether symmetries and collineations of the underlying manifold. In particular we determine the generic Noether symmetry conditions for the approximate point symmetries and we find that for a class of perturbed Lagrangians, Noether symmetries are related to the elements of the Homothetic algebra of the metric which is defined by the unperturbed Lagrangian. Moreover, we discuss how exact symmetries become approximate symmetries. Finally, some applications are presented.

Prediction of human eye fixations using symmetry

NARCIS (Netherlands)

Kootstra, Gert; Schomaker, Lambert

2009-01-01

Humans are very sensitive to symmetry in visual patterns. Reaction time experiments show that symmetry is detected and recognized very rapidly. This suggests that symmetry is a highly salient feature. Existing computational models of saliency, however, have mainly focused on contrast as a measure of

Neural evidence for the intrinsic value of action as motivation for behavior.

Science.gov (United States)

Miura, Naoki; Tanabe, Hiroki C; Sasaki, Akihiro T; Harada, Tokiko; Sadato, Norihiro

2017-06-03

The intrinsic value of an action refers to the inherent sense that experiencing a behavior is enjoyable even if it has no explicit outcome. Previous research has suggested that a common valuation mechanism within the reward network may be responsible for processing the intrinsic value of achieving both the outcome and external rewards. However, how the intrinsic value of action is neurally represented remains unknown. We hypothesized that the intrinsic value of action is determined by an action-outcome contingency indicating the behavior is controllable and that the outcome of the action can be evaluated by this feedback. Consequently, the reward network should be activated, reflecting the generation of the intrinsic value of action. To test this hypothesis, we conducted a functional magnetic resonance imaging (fMRI) investigation of a stopwatch game in which the action-outcome contingency was manipulated. This experiment involved 36 healthy volunteers and four versions of a stopwatch game that manipulated controllability (the feeling that participants were controlling the stopwatch themselves) and outcome (a signal allowing participants to see the result of their action). A free-choice experiment was administered after the fMRI to explore preference levels for each game. The results showed that the stopwatch game with the action-outcome contingency evoked a greater degree of enjoyment because the participants chose this condition over those that lacked such a contingency. The ventral striatum and midbrain were activated only when action-outcome contingency was present. Thus, the intrinsic value of action was represented by an increase in ventral striatal and midbrain activation. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Symmetry and group theory throughout physics

Directory of Open Access Journals (Sweden)

Villain J.

2012-03-01

Full Text Available As noticed in 1884 by Pierre Curie [1], physical properties of matter are tightly related to the kind of symmetry of the medium. Group theory is a systematic tool, though not always easy to handle, to exploit symmetry properties, for instance to find the eigenvectors and eigenvalues of an operator. Certain properties (optical activity, piezoelectricity are forbidden in molecules or crystals of high symmetry. A few theorems (Noether, Goldstone establish general relations between physical properties and symmetry. Applications of group theory to condensed matter physics, elementary particle physics, quantum mechanics, electromagnetism are reviewed. Group theory is not only a tool, but also a beautiful construction which casts insight into natural phenomena.

Singlets of fermionic gauge symmetries

NARCIS (Netherlands)

Bergshoeff, E.A.; Kallosh, R.E.; Rahmanov, M.A.

1989-01-01

We investigate under which conditions singlets of fermionic gauge symmetries which are "square roots of gravity" can exist. Their existence is non-trivial because there are no fields neutral in gravity. We tabulate several examples of singlets of global and local supersymmetry and κ-symmetry and

Hidden symmetries in five-dimensional supergravity

International Nuclear Information System (INIS)

Poessel, M.

2003-05-01

This thesis is concerned with the study of hidden symmetries in supergravity, which play an important role in the present picture of supergravity and string theory. Concretely, the appearance of a hidden G 2(+2) /SO(4) symmetry is studied in the dimensional reduction of d=5, N=2 supergravity to three dimensions - a parallel model to the more famous E 8(+8) /SO(16) case in eleven-dimensional supergravity. Extending previous partial results for the bosonic part, I give a derivation that includes fermionic terms. This sheds new light on the appearance of the local hidden symmetry SO(4) in the reduction, and shows up an unusual feature which follows from an analysis of the R-symmetry associated with N=4 supergravity and of the supersymmetry variations, and which has no parallel in the eleven-dimensional case: The emergence of an additional SO(3) as part of the enhanced local symmetry, invisible in the dimensional reduction of the gravitino, and corresponding to the fact that, of the SO(4) used in the coset model, only the diagonal SO(3) is visible immediately upon dimensional reduction. The uncovering of the hidden symmetries proceeds via the construction of the proper coset gravity in three dimensions, and matching it with the Lagrangian obtained from the reduction. (orig.)

Nuclear symmetry energy in density dependent hadronic models

International Nuclear Information System (INIS)

Haddad, S.

2008-12-01

The density dependence of the symmetry energy and the correlation between parameters of the symmetry energy and the neutron skin thickness in the nucleus 208 Pb are investigated in relativistic Hadronic models. The dependency of the symmetry energy on density is linear around saturation density. Correlation exists between the neutron skin thickness in the nucleus 208 Pb and the value of the nuclear symmetry energy at saturation density, but not with the slope of the symmetry energy at saturation density. (author)

On the intrinsic shape of the gamma-ray spectrum for Fermi blazars

Science.gov (United States)

Kang, Shi-Ju; Wu, Qingwen; Zheng, Yong-Gang; Yin, Yue; Song, Jia-Li; Zou, Hang; Feng, Jian-Chao; Dong, Ai-Jun; Wu, Zhong-Zu; Zhang, Zhi-Bin; Wu, Lin-Hui

2018-05-01

The curvature of the γ-ray spectrumin blazarsmay reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law (PL) or a log-normal (call Logarithmic Parabola, LP) form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3LAC Clean Sample.We find that the γ-ray flux (100MeV–100GeV) and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.

submitter Measurement of LYSO Intrinsic Light Yield Using Electron Excitation

CERN Document Server

Martinez Turtos, Rosana; Pizzichemi, Marco; Ghezzi, Alessio; Pauwels, Kristof; Auffray, Etiennette; Lecoq, Paul; Paganoni, Marco

2016-01-01

The determination of the intrinsic light yield $(LY_{int})$ of scintillating crystals, i.e. number of optical photons created per amount of energy deposited, constitutes a key factor in order to characterize and optimize their energy and time resolution. However, until now measurements of this quantity are affected by large uncertainties and often rely on corrections for bulk absorption and surface/edge state. The novel idea presented in this contribution is based on the confinement of the scintillation emission in the central upper part of a 10 mm cubic crystal using a 1.5 MeV electron beam with diameter of 1 mm. A black non-reflective pinhole aligned with the excitation point is used to fix the light extraction solid angle (narrower than total reflection angle), which then sets a light cone travel path through the crystal. The final number of photoelectrons detected using a Hamamatsu R2059 photomultiplier tube (PMT) was corrected for the extraction solid angle, the Fresnel reflection coefficient and quantum...

Introduction to symmetry-breaking phenomena in physics

CERN Multimedia

CERN. Geneva. Audiovisual Unit

2001-01-01

The notion of broken symmetries started slowly to emerge in the 19th century. The early studies of Pasteur on the parity asymmetry of life, the studies of Curie on piezoelectricity and on the symmetries of effects versus the symmetry of causes ( which clearly excluded spontaneous symmetry breaking), are important historical landmarks. However the possibility of spontaneous symmetry breaking within the usual principles of statistical mechanics, waited for the work of Peierls and Onsager. The whole theory of phase transitions and critical phenomena, as well as the construction of field theoretic models as long distance limit of yet unknown physics, relies nowadays on the concept of criticality associated to spontaneous symmetry breaking. The phenomena of Goldstone bosons, of Meissner-Higgs effects, are central to the theory of condensed matter as well as to particle physics. In cosmology as well, the various inflationary scenarios begin similarly with this same concept. The three lectures will provide a simple ...

Local discrete symmetries from superstring derived models

International Nuclear Information System (INIS)

Faraggi, A.E.

1996-10-01

Discrete and global symmetries play an essential role in many extensions of the Standard Model, for example, to preserve the proton lifetime, to prevent flavor changing neutral currents, etc. An important question is how can such symmetries survive in a theory of quantum gravity, like superstring theory. In a specific string model the author illustrates how local discrete symmetries may arise in string models and play an important role in preventing fast proton decay and flavor changing neutral currents. The local discrete symmetry arises due to the breaking of the non-Abelian gauge symmetries by Wilson lines in the superstring models and forbids, for example dimension five operators which mediate rapid proton decay, to all orders of nonrenormalizable terms. In the context of models of unification of the gauge and gravitational interactions, it is precisely this type of local discrete symmetries that must be found in order to insure that a given model is not in conflict with experimental observations

Symmetry adaptation in two-photon spectroscopy

International Nuclear Information System (INIS)

Kibler, M.

1991-11-01

Symmetry adaptation techniques are applied to the determination of the intensity of two-photon transitions for transition ions in finite symmetry environments. The case of intra-configurational transitions are discussed with some details and some results on inter-configurational transitions are briefly reported. In particular, for intra-configurational transitions, a model is described which takes into account the following ingredients: (symmetry, second- plus third-order mechanisms, S-, L- and J-mixings). (author) 20 refs

Approximate symmetries of Hamiltonians

Science.gov (United States)

Chubb, Christopher T.; Flammia, Steven T.

2017-08-01

We explore the relationship between approximate symmetries of a gapped Hamiltonian and the structure of its ground space. We start by considering approximate symmetry operators, defined as unitary operators whose commutators with the Hamiltonian have norms that are sufficiently small. We show that when approximate symmetry operators can be restricted to the ground space while approximately preserving certain mutual commutation relations. We generalize the Stone-von Neumann theorem to matrices that approximately satisfy the canonical (Heisenberg-Weyl-type) commutation relations and use this to show that approximate symmetry operators can certify the degeneracy of the ground space even though they only approximately form a group. Importantly, the notions of "approximate" and "small" are all independent of the dimension of the ambient Hilbert space and depend only on the degeneracy in the ground space. Our analysis additionally holds for any gapped band of sufficiently small width in the excited spectrum of the Hamiltonian, and we discuss applications of these ideas to topological quantum phases of matter and topological quantum error correcting codes. Finally, in our analysis, we also provide an exponential improvement upon bounds concerning the existence of shared approximate eigenvectors of approximately commuting operators under an added normality constraint, which may be of independent interest.

Symmetries, Integrals and Solutions of Ordinary Differential ...

Indian Academy of Sciences (India)

Second-and third-order scalar ordinary differential equations of maximal symmetry in the traditional sense of point, respectively contact, symmetry are examined for the mappings they produce in solutions and fundamental first integrals. The properties of the `exceptional symmetries', i.e. those not considered to be generic to ...

Collective states and crossing symmetry

International Nuclear Information System (INIS)

Heiss, W.D.

1977-01-01

Collective states are usually described in simple terms but with the use of effective interactions which are supposed to contain more or less complicated contributions. The significance of crossing symmetry is discussed in this connection. Formal problems encountered in the attempts to implement crossing symmetry are pointed out

μ-τ symmetry in Zee-Babu model

International Nuclear Information System (INIS)

Araki, Takeshi; Geng, C.Q.

2010-01-01

We study the Zee-Babu two-loop neutrino mass generation model and look for a possible flavor symmetry behind the tri-bimaximal neutrino mixing. We find that there probably exists the μ-τ symmetry in the case of the normal neutrino mass hierarchy, whereas there may not be in the inverted hierarchy case. We also propose a specific model based on a Froggatt-Nielsen-like Z 5 symmetry to naturally accomplish the μ-τ symmetry on the neutrino mass matrix for the normal hierarchy case.

The weak-scale hierarchy and discrete symmetries

International Nuclear Information System (INIS)

Haba, Naoyuki; Matsuoka, Takeo; Hattori, Chuichiro; Matsuda, Masahisa; Mochinaga, Daizo.

1996-01-01

In the underlying Planck scale theory, we introduce a certain type of discrete symmetry, which potentially brings the stability of the weak-scale hierarchy under control. Under the discrete symmetry the μ-problem and the tadpole problem can be solved simultaneously without relying on some fine-tuning of parameters. Instead, it is required that doublet Higgs and color-triplet Higgs fields reside in different irreducible representations of the gauge symmetry group at the Planck scale and that they have distinct charges of the discrete symmetry group. (author)

Infinite-Order Symmetries for Quantum Separable Systems

International Nuclear Information System (INIS)

Miller, W.; Kalnins, E.G.; Kress, J.M.; Pogosyan, G.S.

2005-01-01

We develop a calculus to describe the (in general) infinite-order differential operator symmetries of a nonrelativistic Schroedinger eigenvalue equation that admits an orthogonal separation of variables in Riemannian n space. The infinite-order calculus exhibits structure not apparent when one studies only finite-order symmetries. The search for finite-order symmetries can then be reposed as one of looking for solutions of a coupled system of PDEs that are polynomial in certain parameters. Among the simple consequences of the calculus is that one can generate algorithmically a canonical basis for the space. Similarly, we can develop a calculus for conformal symmetries of the time-dependent Schroedinger equation if it admits R separation in some coordinate system. This leads to energy-shifting symmetries

Infinite-order symmetries for quantum separable systems

International Nuclear Information System (INIS)

Miller, W.; Kalnins, E.G.; Kress, J.M.; Pogosyan, G.S.

2005-01-01

A calculus to describe the (in general) infinite-order differential operator symmetries of a nonrelativistic Schroedinger eigenvalue equation that admits an orthogonal separation of variables in Riemannian n space is developed. The infinite-order calculus exhibits structure not apparent when one studies only finite-order symmetries. The search for finite-order symmetries can then be reposed as one of looking for solutions of a coupled system of PDEs that are polynomial in certain parameters. Among the simple consequences of the calculus is that one can generate algorithmically a canonical basis for the space. Similarly, it can develop a calculus for conformal symmetries of the time-dependent Schroedinger equation if it admits R separation in some coordinate system. This leads to energy-shifting symmetries [ru

Hidden symmetries of the Principal Chiral Model unveiled

International Nuclear Information System (INIS)

Devchand, C.; Schiff, J.

1996-12-01

By relating the two-dimensional U(N) Principal Chiral Model to a Simple linear system we obtain a free-field parametrization of solutions. Obvious symmetry transformations on the free-field data give symmetries of the model. In this way all known 'hidden symmetries' and Baecklund transformations, as well as a host of new symmetries, arise. (author). 21 refs

Symmetry of quantum intramolecular dynamics

International Nuclear Information System (INIS)

Burenin, Alexander V

2002-01-01

The paper reviews the current progress in describing quantum intramolecular dynamics using merely symmetry principles as a basis. This closed qualitative approach is of particular interest because it is the only method currently available for a broad class of topical problems in the internal dynamics of molecules. Moreover, a molecule makes a physical system whose collective internal motions are geometrically structured, so that its description by perturbation methods requires a symmetry analysis of this structure. The nature of the geometrical symmetry groups crucial for the closed formulation of the qualitative approach is discussed. In particular, the point group of a molecule is of this type. (methodological notes)

A search for symmetries in the genetic code

International Nuclear Information System (INIS)

Hornos, J.E.M.; Hornos, Y.M.M.

1991-01-01

A search for symmetries based on the classification theorem of Cartan for the compact simple Lie algebras is performed to verify to what extent the genetic code is a manifestation of some underlying symmetry. An exact continuous symmetry group cannot be found to reproduce the present, universal code. However a unique approximate symmetry group is compatible with codon assignment for the fundamental amino acids and the termination codon. In order to obtain the actual genetic code, the symmetry must be slightly broken. (author). 27 refs, 3 figs, 6 tabs

Galileo symmetries in polymer particle representation

International Nuclear Information System (INIS)

Chiou, D-W

2007-01-01

To illustrate the conceptual problems for the low-energy symmetries in the continuum of spacetime emerging from the discrete quantum geometry, Galileo symmetries are investigated in the polymer particle representation of a non-relativistic particle as a simple toy model. The complete Galileo transformations (translation, rotation and Galileo boost) are naturally defined in the polymer particle Hilbert space and Galileo symmetries are recovered with highly suppressed deviations in the low-energy regime from the underlying polymer particle description

Local symmetry breaking and spin–phonon coupling in SmCrO{sub 3} orthochromite

Energy Technology Data Exchange (ETDEWEB)

El Amrani, M. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Zaghrioui, M., E-mail: zaghrioui@univ-tours.fr [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Ta Phuoc, V.; Gervais, F. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Massa, Néstor E. [Laboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica-Centro CEQUINOR, Universidad Nacional de La Plata, C. C. 962, 1900 La Plata (Argentina)

2014-06-01

Raman scattering and infrared reflectivity performed on polycrystalline SmCrO{sub 3} support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T{sub N}. Such a behavior is explained by spin–phonon coupling in this compound. Furthermore, temperature dependence of the infrared spectra has demonstrated important changes compared to the Raman spectra, suggesting strong structural modifications due to the cation displacements rather to those of the oxygen ions. Our results reveal that polar distortions originating in local symmetry breaking, i.e. local non-centrosymmetry, resulting in Cr off-centring. - Highlights: • We investigated Raman and infrared phonon modes of SmCrO{sub 3} versus temperature. • Results reveal strong influence of the antiferromagnetic order on phonon modes. • Temperature dependence of the infrared spectra shows strong structural modifications suggesting local symmetry breaking.

Symmetry fractionalization of visons in Z2 spin liquids

Science.gov (United States)

Qi, Yang; Cheng, Meng; Fang, Chen

In this work we study symmetry fractionalization of vison excitations in topological Z2 spin liquids. We show that in the presence of the full SO (3) spin-rotational symmetry and if there is an odd number of spin-1/2 per unit cell, the symmetry fractionalization of visons is completely fixed. On the other hand, visons can have different classes of symmetry fractionalization if the spin-rotational symmetry is reduced. As a concrete example, we show that visons in the Balents-Fisher-Girvin Z2 spin liquid have crystal symmetry fractionalization classes which are not allowed in SO (3) symmetric spin liquids, due to the reduced spin-rotational symmetry.

Geometric phases and hidden local gauge symmetry

International Nuclear Information System (INIS)

Fujikawa, Kazuo

2005-01-01

The analysis of geometric phases associated with level crossing is reduced to the familiar diagonalization of the Hamiltonian in the second quantized formulation. A hidden local gauge symmetry, which is associated with the arbitrariness of the phase choice of a complete orthonormal basis set, becomes explicit in this formulation (in particular, in the adiabatic approximation) and specifies physical observables. The choice of a basis set which specifies the coordinate in the functional space is arbitrary in the second quantization, and a subclass of coordinate transformations, which keeps the form of the action invariant, is recognized as the gauge symmetry. We discuss the implications of this hidden local gauge symmetry in detail by analyzing geometric phases for cyclic and noncyclic evolutions. It is shown that the hidden local symmetry provides a basic concept alternative to the notion of holonomy to analyze geometric phases and that the analysis based on the hidden local gauge symmetry leads to results consistent with the general prescription of Pancharatnam. We however note an important difference between the geometric phases for cyclic and noncyclic evolutions. We also explain a basic difference between our hidden local gauge symmetry and a gauge symmetry (or equivalence class) used by Aharonov and Anandan in their definition of generalized geometric phases

Temporal scaling law and intrinsic characteristic of laser induced damage on the dielectric coating

Science.gov (United States)

Zhou, Li; Jiang, Youen; Wang, Chao; Wei, Hui; Zhang, Peng; Fan, Wei; Li, Xuechun

2018-01-01

High power laser is essential for optical manipulation and fabrication. When the laser travels through optics and to the target finally, irreversible damage on the dielectric coating is always accompanied without knowing the law and principle of laser induced damage. Here, an experimental study of laser induced damage threshold (LIDT) Fth of the dielectric coating under different pulse duration t is implemented. We observe that the temporal scaling law of square pulse for high-reflectivity (HR) coating and anti-reflectivity (AR) coating are Fth = 9.53t0.47 and Fth = 6.43t0.28 at 1064 nm, respectively. Moreover, the intrinsic LIDT of HR coating is 62.7 J/cm2 where the coating is just 100% damaged by gradually increasing the fluence densities of a 5ns-duration pulse, which is much higher than the actual LIDT of 18.6 J/cm2. Thus, a more robust and reliable high power laser system will be a reality, even working at very high fluence, if measures are taken to improve the actual LIDT to a considerable level near the intrinsic value.

Family symmetries in F-theory GUTs

CERN Document Server

King, S F; Ross, G G

2010-01-01

We discuss F-theory SU(5) GUTs in which some or all of the quark and lepton families are assigned to different curves and family symmetry enforces a leading order rank one structure of the Yukawa matrices. We consider two possibilities for the suppression of baryon and lepton number violation. The first is based on Flipped SU(5) with gauge group SU(5)\\times U(1)_\\chi \\times SU(4)_{\\perp} in which U(1)_{\\chi} plays the role of a generalised matter parity. We present an example which, after imposing a Z_2 monodromy, has a U(1)_{\\perp}^2 family symmetry. Even in the absence of flux, spontaneous breaking of the family symmetry leads to viable quark, charged lepton and neutrino masses and mixing. The second possibility has an R-parity associated with the symmetry of the underlying compactification manifold and the flux. We construct an example of a model with viable masses and mixing angles based on the gauge group SU(5)\\times SU(5)_{\\perp} with a U(1)_{\\perp}^3 family symmetry after imposing a Z_2 monodromy.

Violation of Particle Anti-particle Symmetry

CERN Multimedia

CERN. Geneva

2001-01-01

Symmetry is a fundamental concept which can be found in the whole range of human activities e. g. from arts to science. The beauty of a statues is often related to its symmetric form. In physics, all the laws are related to some sort of symmetry. Equally important is a small breakdown ofsymmetry. Even for the case of a statue, its beauty might be enhanced by introducing small distortions. In this course, we investigate the role symmetry in the world of elementary particles. Some symmetries found there are very similar to those which can be seen in our daily life, while others are more exotic and related to the quantum nature of the elementary particles. Our particular focus ismade on symmetry and its violation between the matter and anti-matter, known as CP violation. It is experimentally well established that particleand anti-particle behave a tiny bit differently in the world of elementary particles. We discuss how this would be explained and how we can extendour knowledge. Evolution of our universe is stro...

Progranulin expression in breast cancer with different intrinsic subtypes.

Science.gov (United States)

Li, Li Qin; Min, Li Shan; Jiang, Qun; Ping, Jin Liang; Li, Jing; Dai, Li Cheng

2012-04-15

Progranulin is a newly discovered 88-kDa glycoprotein originally purified from the highly tumorigenic mouse teratoma-derived cell line PC. We found that high progranulin expression was associated with higher breast carcinoma angiogenesis, reflected by increased vascular endothelial growth factor expression and higher microvessel density. However, no immunohistochemical evidence currently exists to correlate progranulin expression with clinicopathological features in different intrinsic subtypes of breast carcinoma biopsies. The aim of this study was to investigate the progranulin expression profiles in the intrinsic subtypes of breast carcinomas and their relevance to histopathological and clinicopathological features. Tissue blocks containing 264 cases of breast carcinomas from 2006 to 2009 were classified as different intrinsic subtypes. Tissues of four intrinsic subtypes were immunostained for progranulin, vascular endothelial growth factor and CD105. Their relevance to histopathological and clinicopathological features was also analyzed. Twenty tissue samples from breast fibroadenomas were included in this study. Progranulin expression showed no significant differences in different intrinsic subtypes, although an increasing tendency could be found in the triple-negative breast cancer (TNBC) subgroup (χ(2)=5.00, df=3, p=0.17). However, differences were significant when pathologically node metastasis-positive (pN(+)) TNBC were excluded (χ(2)=17.84, df=3, pprogranulin in pathologically node metastasis-negative (pN(-)) TNBC. It was noted that the EGFR expression level of the pN(-) TNBC subtype was significantly higher in cases with strong progranulin expression than in cases with weak progranulin expression (χ(2)=11.26, df=1, pprogranulin in pN(-) TNBC suggests that progranulin is a promising new target for pN(-) TNBC treatment. Strong expression of progranulin correlates with positive EGFR expression in the pN(-) TNBC subtype. The close relationship between

Floquet Symmetry-Protected Topological Phases in Cold-Atom Systems

Science.gov (United States)

Potirniche, I.-D.; Potter, A. C.; Schleier-Smith, M.; Vishwanath, A.; Yao, N. Y.

2017-09-01

We propose and analyze two distinct routes toward realizing interacting symmetry-protected topological (SPT) phases via periodic driving. First, we demonstrate that a driven transverse-field Ising model can be used to engineer complex interactions which enable the emulation of an equilibrium SPT phase. This phase remains stable only within a parametric time scale controlled by the driving frequency, beyond which its topological features break down. To overcome this issue, we consider an alternate route based upon realizing an intrinsically Floquet SPT phase that does not have any equilibrium analog. In both cases, we show that disorder, leading to many-body localization, prevents runaway heating and enables the observation of coherent quantum dynamics at high energy densities. Furthermore, we clarify the distinction between the equilibrium and Floquet SPT phases by identifying a unique micromotion-based entanglement spectrum signature of the latter. Finally, we propose a unifying implementation in a one-dimensional chain of Rydberg-dressed atoms and show that protected edge modes are observable on realistic experimental time scales.

Floquet Symmetry-Protected Topological Phases in Cold-Atom Systems.

Science.gov (United States)

Potirniche, I-D; Potter, A C; Schleier-Smith, M; Vishwanath, A; Yao, N Y

2017-09-22

We propose and analyze two distinct routes toward realizing interacting symmetry-protected topological (SPT) phases via periodic driving. First, we demonstrate that a driven transverse-field Ising model can be used to engineer complex interactions which enable the emulation of an equilibrium SPT phase. This phase remains stable only within a parametric time scale controlled by the driving frequency, beyond which its topological features break down. To overcome this issue, we consider an alternate route based upon realizing an intrinsically Floquet SPT phase that does not have any equilibrium analog. In both cases, we show that disorder, leading to many-body localization, prevents runaway heating and enables the observation of coherent quantum dynamics at high energy densities. Furthermore, we clarify the distinction between the equilibrium and Floquet SPT phases by identifying a unique micromotion-based entanglement spectrum signature of the latter. Finally, we propose a unifying implementation in a one-dimensional chain of Rydberg-dressed atoms and show that protected edge modes are observable on realistic experimental time scales.

Extended Galilean symmetries of non-relativistic strings

Energy Technology Data Exchange (ETDEWEB)

Batlle, Carles [Departament de Matemàtiques and IOC, Universitat Politècnica de Catalunya, EPSEVG,Av. V. Balaguer 1, E-08808 Vilanova i la Geltrú (Spain); Gomis, Joaquim; Not, Daniel [Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos (ICCUB),Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain)

2017-02-09

We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.

Braided quantum field theories and their symmetries

International Nuclear Information System (INIS)

Sasai, Yuya; Sasakura, Naoki

2007-01-01

Braided quantum field theories, proposed by Oeckl, can provide a framework for quantum field theories that possess Hopf algebra symmetries. In quantum field theories, symmetries lead to non-perturbative relations among correlation functions. We study Hopf algebra symmetries and such relations in the context of braided quantum field theories. We give the four algebraic conditions among Hopf algebra symmetries and braided quantum field theories that are required for the relations to hold. As concrete examples, we apply our analysis to the Poincare symmetries of two examples of noncommutative field theories. One is the effective quantum field theory of three-dimensional quantum gravity coupled to spinless particles formulated by Freidel and Livine, and the other is noncommutative field theory on the Moyal plane. We also comment on quantum field theory in κ-Minkowski spacetime. (author)

Universe symmetries

International Nuclear Information System (INIS)

Souriau, J.M.

1984-01-01

The sky uniformity can be noticed in studying the repartition of objects far enough. The sky isotropy description uses space rotations. The group theory elements will allow to give a meaning at the same time precise and general to the word a ''symmetry''. Universe models are reviewed, which must have both of the following qualities: - conformity with the physic known laws; - rigorous symmetry following one of the permitted groups. Each of the models foresees that universe evolution obeys an evolution equation. Expansion and big-bang theory are recalled. Is universe an open or closed space. Universe is also electrically neutral. That leads to a work hypothesis: the existing matter is not given data of universe but it appeared by evolution from nothing. Problem of matter and antimatter is then raised up together with its place in universe [fr

Structured self-reflection as a tool to enhance perceived performance and maintain effort in adult recreational salsa dancers

Science.gov (United States)

The purpose of this study was to determine if the use of structured self-reflection in community dance classes would influence achievement goal orientations, levels of intrinsic motivation, or perceived dance performance. The Task and Ego Orientation in Sport Questionnaire (TEOSQ) and the Intrinsic...

Integrable systems and lie symmetries in classical mechanics

International Nuclear Information System (INIS)

Sen, T.

1986-01-01

The interrelationship between integrability and symmetries in classical mechanics is studied. Two-dimensional time- and velocity-independent potentials form the domain of the study. It is shown that, contrary to folklore, existence of a single finite symmetry does not ensure integrability. A method due to Darboux is used to construct potentials that admit a time-independent invariant. All potentials admitting invariants linear or quadratic in the momentum coordinates are constructed. These are the only integrable potentials which can be expressed as arbitrary functions of certain arguments. A complete construction of potentials admitting higher-order invariants does not seem possible. However, the necessary general forms for potentials that admit a particular invariant of arbitrary order are found. These invariants must be spherically symmetric in the leading terms. Two kinds of symmetries are studied: point Lie symmetries of the Newtonian equations of motion for conservative potentials, and point Noether symmetries of the action functionals obtained from the standard Lagrangians associated with these potentials. All conservative potentials which admit these symmetries are constructed. The class of potentials admitting Noether symmetries is shown to be a subclass of those admitting Lie symmetries

The dark side of monetary incentive: how does extrinsic reward crowd out intrinsic motivation.

Science.gov (United States)

Ma, Qingguo; Jin, Jia; Meng, Liang; Shen, Qiang

2014-02-12

It was widely believed that incentives could effectively enhance the motivation of both students and employees. However, psychologists reported that extrinsic reward actually could undermine individuals' intrinsic motivation to a given interesting task, which challenged viewpoints from traditional incentive theories. Numerous studies have been carried out to test and explain the undermining effect; however, the neural basis of this effect is still elusive. Here, we carried out an electrophysiological study with a simple but interesting stopwatch task to explore to what extent the performance-based monetary reward undermines individuals' intrinsic motivation toward the task. The electrophysiological data showed that the differentiated feedback-related negativity amplitude toward intrinsic success failure divergence was prominently reduced once the extrinsic reward was imposed beforehand. However, such a difference was not observed in the control group, in which no extrinsic reward was provided throughout the experiment. Furthermore, such a pattern was not observed for P300 amplitude. Therefore, the current results indicate that extrinsic reward demotivates the intrinsic response of individuals toward success-failure outcome, which was reflected in the corresponding reduced motivational-related differentiated feedback-related negativity, but not in amplitude of P300.

Spontaneously broken global symmetries and cosmology

International Nuclear Information System (INIS)

Shafi, Q.; Vilenkin, A.

1984-01-01

Phase transitions associated with spontaneously broken global symmetries, in case these occur in nature, can have important cosmological implications. This is illustrated through two examples. The first one shows how the spontaneous breaking of a global U(1) symmetry, present, for instance, in the minimal SU(5) model, can lead to an inflationary phase. The second example illustrates how topologically stable strings associated with the breaking of U(1) symmetry make an appearance at (or near) the end of the inflationary era

Fermion dynamical symmetry and identical bands

International Nuclear Information System (INIS)

Guidry, M.

1994-01-01

Recent general attention has been directed to the phenomenon of identical bands in both normally deformed and superdeformed nuclei. This paper discusses the possibility that such behavior results from a dynamical symmetry of the nuclear many-body system. Phenomenology and the basic principles of Lie algebras are used to place conditions on the acceptable properties of a candidate symmetry. We find that quite general arguments require that such a symmetry have a minimum of 21 generators with a microscopic fermion interpretation

Two-plane symmetry in the structural organization of man.

Science.gov (United States)

Ermolenko, A E

2005-01-01

Manifestations of symmetry in the human structural organization in ontogenesis and phylogenetic development are analysed. A concept of macrobiocrystalloid with inherent complex symmetry is proposed for the description of the human organism in its integrity. The symmetry can be characterized as two-plane radial (quadrilateral), where the planar symmetry is predominant while the layout of organs of radial symmetry is subordinated to it. Out of the two planes of symmetry (sagittal and horizontal), the sagittal plane is predominant: (a) the location of the organs is governed by two principles: in compliance with the symmetry planes and in compliance with the radial symmetry around cavities; (b) the location of the radial symmetry organs is also governed by the principle of two-plane symmetry; (c) out of the four antimeres of two-plane symmetry, two are paired while the other two have merged into one organ; (d) some organs which are antimeres relative to the horizontal plane are located at the cranial end of the organism (sensory organs, cerebrum-cerebellum, heart-spleen and others). The two-plane symmetry is formed by two mechanisms--(a) the impact of morphogenetic fields of the whole crystalloid organism during embriogenesis and (b) genetic mechanisms of the development of chromosomes having two-plane symmetry. When comparing mineral and biological entities we should consider not the whole immobile crystal but only the active superficial part of a growing or dissolving crystal, the interface between the crystal surface and the crystal-forming environment which directly controls crystal growth and adapts itself to it, as well as crystal feed stock expressed in the structure of concentration flows. The symmetry of the chromosome, of the embrion at the early stages of cell cleavage as well as of some organs and systems in their phylogenetic development is described.

What does facial symmetry reveal about health and personality?

Directory of Open Access Journals (Sweden)

Švegar Domagoj

2016-09-01

Full Text Available Over the last two decades, facial symmetry has been intensively researched. The present article aims to summarize empirical research concerning relations between facial symmetry and health and facial symmetry and personality. A systematic review of the literature shows that facial symmetry is one of the most influential visual markers of attractiveness and health, important for mate selection, while asymmetry can be considered a consequence of an individual’s inability to resist environmental and genetic stressors during development of the organism. However, in spite of evidence suggesting that preferences for facial symmetry are deeply rooted in our evolutionary history, a strong connection between facial symmetry and health is demonstrated only in studies measuring perceived health, while there is only scarce evidence corroborating the link between symmetry and actual health. The interconnections between facial symmetry and personality have not yet been extensively researched. Less than a dozen studies have addressed that issue and they have reached different conclusions. Some evidence suggests that facial symmetry signals personality attributes that indicate good psychological health, while other findings imply that pro-social personality traits negatively correlate with facial symmetry.

Nonlocal Symmetries to Systems of Nonlinear Diffusion Equations

International Nuclear Information System (INIS)

Qu Changzheng; Kang Jing

2008-01-01

In this paper, we study potential symmetries to certain systems of nonlinear diffusion equations. Those systems have physical applications in soil science, mathematical biology, and invariant curve flows in R 3 . Lie point symmetries of the potential system, which cannot be projected to vector fields of the given dependent and independent variables, yield potential symmetries. The class of the system that admits potential symmetries is expanded.

Symmetry protected topological charge in symmetry broken phase: Spin-Chern, spin-valley-Chern and mirror-Chern numbers

International Nuclear Information System (INIS)

Ezawa, Motohiko

2014-01-01

The Chern number is a genuine topological number. On the other hand, a symmetry protected topological (SPT) charge is a topological number only when a symmetry exists. We propose a formula for the SPT charge as a derivative of the Chern number in terms of the Green function in such a way that it is valid and related to the associated Hall current even when the symmetry is broken. We estimate the amount of deviation from the quantized value as a function of the strength of the broken symmetry. We present two examples. First, we consider Dirac electrons with the spin–orbit coupling on honeycomb lattice, where the SPT charges are given by the spin-Chern, valley-Chern and spin-valley-Chern numbers. Though the spin-Chern charge is not quantized in the presence of the Rashba coupling, the deviation is estimated to be 10 −7 in the case of silicene, a silicon cousin of graphene. Second, we analyze the effect of the mirror-symmetry breaking of the mirror-Chern number in a thin-film of topological crystalline insulator.

Symmetry guide to ferroaxial transitions

Czech Academy of Sciences Publication Activity Database

Hlinka, Jiří; Přívratská, J.; Ondrejkovič, Petr; Janovec, Václav

2016-01-01

Roč. 116, č. 17 (2016), 1-6, č. článku 177602. ISSN 0031-9007 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : symmetry * symmetry breaking * ferroaxial Transitions * property tensors * Aizu species Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.462, year: 2016

Coupled oscillators with parity-time symmetry

Energy Technology Data Exchange (ETDEWEB)

Tsoy, Eduard N., E-mail: etsoy@uzsci.net

2017-02-05

Different models of coupled oscillators with parity-time (PT) symmetry are studied. Hamiltonian functions for two and three linear oscillators coupled via coordinates and accelerations are derived. Regions of stable dynamics for two coupled oscillators are obtained. It is found that in some cases, an increase of the gain-loss parameter can stabilize the system. A family of Hamiltonians for two coupled nonlinear oscillators with PT-symmetry is obtained. An extension to high-dimensional PT-symmetric systems is discussed. - Highlights: • A generalization of a Hamiltonian system of linear coupled oscillators with the parity-time (PT) symmetry is suggested. • It is found that an increase of the gain-loss parameter can stabilize the system. • A family of Hamiltonian functions for two coupled nonlinear oscillators with PT-symmetry is obtained.

Reflective Practice in the Clinical Setting: A Multi-Institutional Qualitative Study of Pediatric Faculty and Residents.

Science.gov (United States)

Plant, Jennifer; Li, Su-Ting T; Blankenburg, Rebecca; Bogetz, Alyssa L; Long, Michele; Butani, Lavjay

2017-11-01

To explore when and in what form pediatric faculty and residents practice reflection. From February to June 2015, the authors conducted focus groups of pediatric faculty and residents at the University of California, Davis; Stanford University; and the University of California, San Francisco, until thematic saturation occurred. Transcripts were analyzed based on Mezirow's and Schon's models of reflection, using the constant comparative method associated with grounded theory. Two investigators independently coded transcripts and reconciled codes to develop themes. All investigators reviewed the codes and developed a final list of themes through consensus. Through iterative discussions, investigators developed a conceptual model of reflection in the clinical setting. Seventeen faculty and 20 residents from three institutions participated in six focus groups. Five themes emerged: triggers of reflection, intrinsic factors, extrinsic factors, timing, and outcome of reflection. Various triggers led to reflection; whether a specific trigger led to reflection depended on intrinsic and extrinsic factors. When reflection occurred, it happened in action or on action. Under optimal conditions, this reflection was goal and action directed and became critical reflection. In other instances, this process resulted in unproductive rumination or acted as an emotional release or supportive therapy. Participants reflected in clinical settings, but did not always explicitly identify it as reflection or reflect in growth-promoting ways. Strategies to enhance critical reflection include developing knowledge and skills in reflection, providing performance data to inform reflection, creating time and space for safe reflection, and providing mentorship to guide the process.

On the Incompleteness of Ibragimov’s Conservation Law Theorem and Its Equivalence to a Standard Formula Using Symmetries and Adjoint-Symmetries

Directory of Open Access Journals (Sweden)

Stephen C. Anco

2017-02-01

Full Text Available A conservation law theorem stated by N. Ibragimov along with its subsequent extensions are shown to be a special case of a standard formula that uses a pair consisting of a symmetry and an adjoint-symmetry to produce a conservation law through a well-known Fréchet derivative identity. Furthermore, the connection of this formula (and of Ibragimov’s theorem to the standard action of symmetries on conservation laws is explained, which accounts for a number of major drawbacks that have appeared in recent work using the formula to generate conservation laws. In particular, the formula can generate trivial conservation laws and does not always yield all non-trivial conservation laws unless the symmetry action on the set of these conservation laws is transitive. It is emphasized that all local conservation laws for any given system of differential equations can be found instead by a general method using adjoint-symmetries. This general method is a kind of adjoint version of the standard Lie method to find all local symmetries and is completely algorithmic. The relationship between this method, Noether’s theorem and the symmetry/adjoint-symmetry formula is discussed.

Preferences for symmetry in human faces in two cultures: data from the UK and the Hadza, an isolated group of hunter-gatherers.

Science.gov (United States)

Little, Anthony C; Apicella, Coren L; Marlowe, Frank W

2007-12-22

Many studies show agreement within and between cultures for general judgements of facial attractiveness. Few studies, however, have examined the attractiveness of specific traits and few have examined preferences in hunter-gatherers. The current study examined preferences for symmetry in both the UK and the Hadza, a hunter-gatherer society of Tanzania. We found that symmetry was more attractive than asymmetry across both the cultures and was more strongly preferred by the Hadza than in the UK. The different ecological conditions may play a role in generating this difference. Such variation in preference may be adaptive if it reflects adaptation to local conditions. Symmetry is thought to indicate genetic quality, which may be more important among the Hadza with much higher mortality rates from birth onwards. Hadza men who were more often named as good hunters placed a greater value on symmetry in female faces. These results suggest that high quality Hadza men are more discriminating in their choice of faces. Hadza women had increased preferences for symmetry in men's faces when they were pregnant or nursing, perhaps due to their increased discrimination and sensitivity to foods and disease harmful to a foetus or nursing infant. These results imply that symmetry is an evolutionarily relevant trait and that variation in symmetry preference appears strategic both between cultures and within individuals of a single culture.

Spontaneous symmetry breaking and its cosmological consequences

International Nuclear Information System (INIS)

Kobzarev, I.Yu.

1975-01-01

The concept of symmetry and of the spontaneous symmetry breaking are presented in popular form as applied to quantum physics. Though the presence of the spontaneous symmetry breaking is not proved directly for interactions of elementary particles, on considering the hypothesis of its presence as applied to the hot Universe theory a possibility of obtaining rather uncommon cosmological consequences is discussed. In particular, spontaneous symmetry breaking of vacuum and the rather hot Universe lead necessarily to the presence of the domain structure of the Universe with the surfase energy at the domain interface in the form of a real physical object

Fields, symmetries, and quarks

International Nuclear Information System (INIS)

Mosel, U.

1989-01-01

'Fields, symmetries, and quarks' covers elements of quantum field theory, symmetries, gauge field theories and phenomenological descriptions of hadrons, with special emphasis on topics relevant to nuclear physics. It is aimed at nuclear physicists in general and at scientists who need a working knowledge of field theory, symmetry principles of elementary particles and their interactions and the quark structure of hadrons. The book starts out with an elementary introduction into classical field theory and its quantization. As gauge field theories require a working knowledge of global symmetries in field theories this topic is then discussed in detail. The following part is concerned with the general structure of gauge field theories and contains a thorough discussion of the still less widely known features of Non-Abelian gauge field theories. Quantum Chromodynamics (QCD), which is important for the understanding of hadronic matter, is discussed in the next section together with the quark compositions of hadrons. The last two chapters give a detailed discussion of phenomenological bag-models. The MIT bag is discussed, so that all theoretical calculations can be followed step by step. Since in all other bag-models the calculational methods and steps are essentially identical, this chapter should enable the reader to actually perform such calculations unaided. A last chapter finally discusses the topological bag-models which have become quite popular over the last few years. (orig.)

Robustness of the division symmetry in Escherichia coli and functional consequences of symmetry breaking

International Nuclear Information System (INIS)

Gupta, Abhishekh; Lloyd-Price, Jason; Oliveira, Samuel M D; Yli-Harja, Olli; Muthukrishnan, Anantha-Barathi; Ribeiro, Andre S

2014-01-01

The morphological symmetry of the division process of Escherichia coli is well-known. Recent studies verified that, in optimal growth conditions, most divisions are symmetric, although there are exceptions. We investigate whether such morphological asymmetries in division introduce functional asymmetries between sister cells, and assess the robustness of the symmetry in division to mild chemical stresses and sub-optimal temperatures. First, we show that the difference in size between daughter cells at birth is positively correlated to the difference between the numbers of fluorescent protein complexes inherited from the parent cell. Next, we show that the degree of symmetry in division observed in optimal conditions is robust to mild acidic shift and to mild oxidative stress, but not to sub-optimal temperatures, in that the variance of the difference between the sizes of sister cells at birth is minimized at 37 °C. This increased variance affects the functionality of the cells in that, at sub-optimal temperatures, larger/smaller cells arising from asymmetric divisions exhibit faster/slower division times than the mean population division time, respectively. On the other hand, cells dividing faster do not do so at the cost of morphological symmetry in division. Finally we show that at suboptimal temperatures the mean distance between the nucleoids increases, explaining the increased variance in division. We conclude that the functionality of E. coli cells is not immune to morphological asymmetries at birth, and that the effectiveness of the mechanism responsible for ensuring the symmetry in division weakens at sub-optimal temperatures. (paper)

Atomic Nuclei with Tetrahedral and Octahedral Symmetries

International Nuclear Information System (INIS)

Dudek, J.; Gozdz, A.; Schunck, N.

2003-01-01

We present possible manifestations of octahedral and tetrahedral symmetries in nuclei. These symmetries are associated with the O D h and T D d double point groups. Both of them have very characteristic finger-prints in terms of the nucleonic level properties - unique in the Fermionic universe. The tetrahedral symmetry leads to the four-fold degeneracies in the nucleonic spectra; it does not preserve the parity. The octahedral symmetry leads to the four-fold degeneracies in the nucleonic spectra as well but it does preserve the parity. Microscopic predictions have been obtained using mean-field theory based on the relativistic equations and confirmed by using ''traditional'' Schrodinger equation formalism. Calculations are performed in multidimensional deformation spaces using newly designed algorithms. We discuss some experimental fingerprints of the hypothetical new symmetries and possibilities of their verification through experiments. (author)

Symmetry Breaking in MILP Formulations for Unit Commitment Problems

KAUST Repository

Lima, Ricardo

2015-12-11

This paper addresses the study of symmetry in Unit Commitment (UC) problems solved by Mixed Integer Linear Programming (MILP) formulations, and using Linear Programming based Branch & Bound MILP solvers. We propose three sets of symmetry breaking constraints for UC MILP formulations exhibiting symmetry, and its impact on three UC MILP models are studied. The case studies involve the solution of 24 instances by three widely used models in the literature, with and without symmetry breaking constraints. The results show that problems that could not be solved to optimality within hours can be solved with a relatively small computational burden if the symmetry breaking constraints are assumed. The proposed symmetry breaking constraints are also compared with the symmetry breaking methods included in two MILP solvers, and the symmetry breaking constraints derived in this work have a distinct advantage over the methods in the MILP solvers.

Symmetry Breaking in MILP Formulations for Unit Commitment Problems

KAUST Repository

Lima, Ricardo; Novais, Augusto Q.

2015-01-01

This paper addresses the study of symmetry in Unit Commitment (UC) problems solved by Mixed Integer Linear Programming (MILP) formulations, and using Linear Programming based Branch & Bound MILP solvers. We propose three sets of symmetry breaking constraints for UC MILP formulations exhibiting symmetry, and its impact on three UC MILP models are studied. The case studies involve the solution of 24 instances by three widely used models in the literature, with and without symmetry breaking constraints. The results show that problems that could not be solved to optimality within hours can be solved with a relatively small computational burden if the symmetry breaking constraints are assumed. The proposed symmetry breaking constraints are also compared with the symmetry breaking methods included in two MILP solvers, and the symmetry breaking constraints derived in this work have a distinct advantage over the methods in the MILP solvers.

CP properties of symmetry-constrained two-Higgs-doublet models

CERN Document Server

Ferreira, P M; Nachtmann, O; Silva, Joao P

2010-01-01

The two-Higgs-doublet model can be constrained by imposing Higgs-family symmetries and/or generalized CP symmetries. It is known that there are only six independent classes of such symmetry-constrained models. We study the CP properties of all cases in the bilinear formalism. An exact symmetry implies CP conservation. We show that soft breaking of the symmetry can lead to spontaneous CP violation (CPV) in three of the classes.

Flavour from accidental symmetries

International Nuclear Information System (INIS)

Ferretti, Luca; King, Stephen F.; Romanino, Andrea

2006-01-01

We consider a new approach to fermion masses and mixings in which no special 'horizontal' dynamics is invoked to account for the hierarchical pattern of charged fermion masses and for the peculiar features of neutrino masses. The hierarchy follows from the vertical, family-independent structure of the model, in particular from the breaking pattern of the Pati-Salam group. The lightness of the first two fermion families can be related to two family symmetries emerging in this context as accidental symmetries

Discrete symmetries and coset space dimensional reduction

International Nuclear Information System (INIS)

Kapetanakis, D.; Zoupanos, G.

1989-01-01

We consider the discrete symmetries of all the six-dimensional coset spaces and we apply them in gauge theories defined in ten dimensions which are dimensionally reduced over these homogeneous spaces. Particular emphasis is given in the consequences of the discrete symmetries on the particle content as well as on the symmetry breaking a la Hosotani of the resulting four-dimensional theory. (orig.)

Kac-Moody-Virasoro Symmetries and Related Conservation Laws

International Nuclear Information System (INIS)

Lou, S. Y.; Jia, M.; Tang, X. Y.

2010-01-01

In this report, some important facts on the symmetries and conservation laws of high dimensional integrable systems are discussed. It is summarized that almost all the known (2+1)-dimensional integrable models possess the Kac-Moody-Virasoro (KMV) symmetry algebras. One knows that infinitely many partial differential equations may possess a same KMV symmetry algebra. It is found that the KMV symmetry groups can be explicitly obtained by using some direct methods. For some quite general variable coefficient nonlinear systems, their sufficient and necessary condition for the existence of the KMV symmetry algebra is they can be changed to the related known constant coefficient models. Finally, it is found that every one symmetry may be related to infinitely many conservation laws and then infinitely many models may possess a same set of infinitely many conservation laws.

Rencontres de Moriond EW 2012: Addressing symmetry breaking and mass hierarchy

CERN Multimedia

Pauline Gagnon

2012-01-01

Last Friday at the Moriond conference in La Thuile in Italy, Lisa Randall from Harvard University reminded the audience how all fields are related: electroweak symmetry breaking must take into account flavour physics for example. Every good model should address this intrinsic connection.   Despite many expectations, no signs for supersymmetry (SUSY) of any type has been found to date. So Lisa Randall worked with Csaba Csaki and John Terning to explore alternatives and developed a version of supersymmetry built on the Minimal Composite Supersymmetry Standard Model (MCSSM) that Csaki, Shirman, and Terning had developed, incorporating a strongly interacting theory with compositeness that addresses among other things the fact that the top quark is so much heavier than all other quarks. Randall and collaborators showed that this model, when supersymmetry is incorporated, naturally accommodates both a Higgs boson around 125 GeV and a light stop, the supersymmetric partner to the top quark. &a...

Fermion dynamical symmetry and identical bands

International Nuclear Information System (INIS)

Guidry, M.

1995-01-01

Recent general attention has been directed to the phenomenon of identical bands in both normally deformed and superdeformed nuclei. This paper discusses the possibility that such behavior results from a dynamical symmetry of the nuclear many-body system. Phenomenology and the basis principles of Lie algebras are used to place conditions on the acceptable properties of a candidate symmetry. We find that quite general arguments require that such a symmetry have a minimum of 21 generators with a microscopic fermion interpretation. (author). 9 refs., 11 figs., 1 tab

Hairs of discrete symmetries and gravity

Energy Technology Data Exchange (ETDEWEB)

Choi, Kang Sin [Scranton Honors Program, Ewha Womans University, Seodaemun-Gu, Seoul 03760 (Korea, Republic of); Center for Fields, Gravity and Strings, CTPU, Institute for Basic Sciences, Yuseong-Gu, Daejeon 34047 (Korea, Republic of); Kim, Jihn E., E-mail: jihnekim@gmail.com [Department of Physics, Kyung Hee University, 26 Gyungheedaero, Dongdaemun-Gu, Seoul 02447 (Korea, Republic of); Center for Axion and Precision Physics Research (IBS), 291 Daehakro, Yuseong-Gu, Daejeon 34141 (Korea, Republic of); Kyae, Bumseok [Department of Physics, Pusan National University, 2 Busandaehakro-63-Gil, Geumjeong-Gu, Busan 46241 (Korea, Republic of); Nam, Soonkeon [Department of Physics, Kyung Hee University, 26 Gyungheedaero, Dongdaemun-Gu, Seoul 02447 (Korea, Republic of)

2017-06-10

Gauge symmetries are known to be respected by gravity because gauge charges carry flux lines, but global charges do not carry flux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs fields, a string-like configuration (hair) at the intersection of domain walls in the Higgs vacua can be realized. Therefore, we argue that discrete charges are also respected by gravity.

Hairs of discrete symmetries and gravity

Directory of Open Access Journals (Sweden)

Kang Sin Choi

2017-06-01

Full Text Available Gauge symmetries are known to be respected by gravity because gauge charges carry flux lines, but global charges do not carry flux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs fields, a string-like configuration (hair at the intersection of domain walls in the Higgs vacua can be realized. Therefore, we argue that discrete charges are also respected by gravity.

Effect of Medium Symmetries in Limiting the Number of Parameters Estimated with Polarimetric Interferometry

Science.gov (United States)

Moghaddam, Mahta

2000-01-01

The addition of interferometric backscattering pairs to the conventional polarimetric SAR data over forests and other vegetated areas increases the dimensionality of the data space, in principle enabling the estimation of a larger number of vegetation parameters. Without regard to the sensitivity of these data to vegetation scattering parameters, this paper poses the question: Will increasing the data channels as such result in a one-to-one increase in the number of parameters that can be estimated, or do vegetation and data properties inherently limit that number otherwise? In this paper, the complete polarimetric interferometric covariance matrix is considered and various symmetry properties of the scattering medium are used to study whether any of the correlation pairs can be eliminated. The number of independent pairs has direct consequences in their utility in parameter estimation schemes, since the maximum number of parameters that can be estimated cannot exceed the number of unique measurements. The independent components of the polarimetric interferometric SAR (POL/INSAR) data are derived for media with reflection, rotation, and azimuth symmetries, which are often encountered in vegetated surfaces. Similar derivations have been carried out before for simple polarimetry, i.e., zero baseline. This paper extends those to the interferometric case of general nonzero baselines. It is shown that depending on the type of symmetries present, the number of independent available measurements that can be used to estimate medium parameters will vary. In particular, whereas in the general case there are 27 mathematically independent measurements possible from a polarimetric interferometer, this number can be reduced to 15, 9, and 6 if the medium has reflection, rotation, or azimuthal symmetries, respectively. The results can be used in several ways in the interpretation of SAR data and the development of parameter estimation schemes, which will be discussed at the

Spontaneous symmetry breakdown in gauge theories

International Nuclear Information System (INIS)

Scadron, M.D.

1982-01-01

The dynamical theory of spontaneous breakdown correctly predicts the bound states and relates the order parameters of electron-photon superconductivity and quark-gluon chiral symmetry. A similar statement cannot be made for the standard electro-weak gauge symmetry. (author)

Classical symmetries of some two-dimensional models

International Nuclear Information System (INIS)

Schwarz, J.H.

1995-01-01

It is well-known that principal chiral models and symmetric space models in two-dimensional Minkowski space have an infinite-dimensional algebra of hidden symmetries. Because of the relevance of symmetric space models to duality symmetries in string theory, the hidden symmetries of these models are explored in some detail. The string theory application requires including coupling to gravity, supersymmetrization, and quantum effects. However, as a first step, this paper only considers classical bosonic theories in flat space-time. Even though the algebra of hidden symmetries of principal chiral models is confirmed to include a Kac-Moody algebra (or a current algebra on a circle), it is argued that a better interpretation is provided by a doubled current algebra on a semi-circle (or line segment). Neither the circle nor the semi-circle bears any apparent relationship to the physical space. For symmetric space models the line segment viewpoint is shown to be essential, and special boundary conditions need to be imposed at the ends. The algebra of hidden symmetries also includes Virasoro-like generators. For both principal chiral models and symmetric space models, the hidden symmetry stress tensor is singular at the ends of the line segment. (orig.)

Genome-Wide Prediction of Intrinsic Disorder; Sequence Alignment of Intrinsically Disordered Proteins

Science.gov (United States)

Midic, Uros

2012-01-01

Intrinsic disorder (ID) is defined as a lack of stable tertiary and/or secondary structure under physiological conditions in vitro. Intrinsically disordered proteins (IDPs) are highly abundant in nature. IDPs possess a number of crucial biological functions, being involved in regulation, recognition, signaling and control, e.g. their functional…

STS, symmetry and post-truth.

Science.gov (United States)

Lynch, Michael

2017-08-01

This essay takes up a series of questions about the connection between 'symmetry' in Science and Technology Studies (STS) and 'post-truth' in contemporary politics. A recent editorial in this journal by Sergio Sismondo argues that current discussions of 'post-truth' have little to do with conceptions of 'symmetry' or with concerns about 'epistemic democracy' in STS, while others, such as Steve Fuller and Harry Collins, insist that there are such connections. The present essay discusses a series of questions about the meaning of 'post-truth' and 'symmetry', and the connections of those concepts to each other and to 'epistemic democracy'. The essay ends with a series of other questions about STS and contemporary politics, and an invitation to further discussions.

Symmetry, structure, and spacetime

CERN Document Server

Rickles, Dean

2007-01-01

In this book Rickles considers several interpretative difficulties raised by gauge-type symmetries (those that correspond to no change in physical state). The ubiquity of such symmetries in modern physics renders them an urgent topic in philosophy of physics. Rickles focuses on spacetime physics, and in particular classical and quantum general relativity. Here the problems posed are at their most pathological, involving the apparent disappearance of spacetime! Rickles argues that both traditional ontological positions should be replaced by a structuralist account according to which relational

To see symmetry in a forest of trees

International Nuclear Information System (INIS)

Chan, Chuan-Tsung; Kawamoto, Shoichi; Tomino, Dan

2014-01-01

The exact symmetry identities among four-point tree-level amplitudes of bosonic open string theory as derived by G.W. Moore are re-examined. The main focuses of this work are: (1) Explicit construction of kinematic configurations and a new polarization basis for the scattering processes. These setups simplify greatly the functional forms of the exact symmetry identities, and help us to extract easily high-energy limits of stringy amplitudes appearing in the exact identities. (2) Connection and comparison between D.J. Gross's high-energy stringy symmetry and the exact symmetry identities as derived by G.W. Moore. (3) Observation of symmetry patterns of stringy amplitudes with respect to the order of energy dependence in scattering amplitudes

Symmetry and symmetry restoration of lattice chiral fermions in the overlap formalism

International Nuclear Information System (INIS)

Kikukawa, Y.

1999-01-01

Three aspects of the symmetry structure of lattice chiral fermions in the overlap formalism are discussed. By the weak coupling expansion of the overlap Dirac operator, the axial anomaly associated to the chiral transformation proposed by Luescher is evaluated and is shown to have the correct form of the topological charge density for perturbative backgrounds. Next we discuss the exponential suppression of the self-energy correction of the lightest mode in the domain-wall fermion/truncated overlap. Finally, we consider a supersymmetric extension of the overlap formula in the case of the chiral multiplet and examine the symmetry structure of the action

Charge-symmetry-breaking nucleon form factors

International Nuclear Information System (INIS)

Kubis, Bastian

2011-01-01

A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon’s strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for 4 He.

Dark Energy and Spacetime Symmetry

Directory of Open Access Journals (Sweden)

Irina Dymnikova

2017-03-01

Full Text Available The Petrov classification of stress-energy tensors provides a model-independent definition of a vacuum by the algebraic structure of its stress-energy tensor and implies the existence of vacua whose symmetry is reduced as compared with the maximally symmetric de Sitter vacuum associated with the Einstein cosmological term. This allows to describe a vacuum in general setting by dynamical vacuum dark fluid, presented by a variable cosmological term with the reduced symmetry which makes vacuum fluid essentially anisotropic and allows it to be evolving and clustering. The relevant solutions to the Einstein equations describe regular cosmological models with time-evolving and spatially inhomogeneous vacuum dark energy, and compact vacuum objects generically related to a dark energy: regular black holes, their remnants and self-gravitating vacuum solitons with de Sitter vacuum interiors—which can be responsible for observational effects typically related to a dark matter. The mass of objects with de Sitter interior is generically related to vacuum dark energy and to breaking of space-time symmetry. In the cosmological context spacetime symmetry provides a mechanism for relaxing cosmological constant to a needed non-zero value.

Is CP a gauge symmetry?

International Nuclear Information System (INIS)

Choi, K.; Kaplan, D.B.; Nelson, A.E.

1993-01-01

Conventional solutions to the strong CP problem all require the existence of global symmetries. However, quantum gravity may destroy global symmetries, making it hard to understand why the electric dipole moment of the neutron (EDMN) is so small. We suggest here that CP is actually a discrete gauge symmetry, and is therefore not violated by quantum gravity. We show that four-dimensional CP can arise as a discrete gauge symmetry in theories with dimensional compactification, if the original number of Minkowski dimensions equals 8k+1, 8k+2 or 8k+3, and if there are certain restrictions on the gauge group; these conditions are met by superstrings. CP may then be broken spontaneously below 10 9 GeV, explaining the observed CP violation in the kaon system without inducing a large EDMN. We discuss the phenomenology of such models, as well as the peculiar properties of cosmic 'SP strings' which could be produced at the compactification scale. Such strings have the curious property that a particle carried around the string is turned into its CP conjugate. A single CP string renders four-dimensional space-time nonorientable. (orig.)

On nonlocal symmetries of some shallow water equations

Energy Technology Data Exchange (ETDEWEB)

Reyes, Enrique G [Departamento de Matematicas y Ciencia de la Computacion, Universidad de Santiago de Chile, Casilla 307 Correo 2 Santiago (Chile)

2007-04-27

A recent construction of nonlocal symmetries for the Korteweg-de Vries, Camassa-Holm and Hunter-Saxton equations is reviewed, and it is pointed out that-in the Camassa-Holm and Hunter-Saxton case-these symmetries can be considered as (nonlocal) symmetries of integro-differential equations.

Recursions of Symmetry Orbits and Reduction without Reduction

Directory of Open Access Journals (Sweden)

Andrei A. Malykh

2011-04-01

Full Text Available We consider a four-dimensional PDE possessing partner symmetries mainly on the example of complex Monge-Ampère equation (CMA. We use simultaneously two pairs of symmetries related by a recursion relation, which are mutually complex conjugate for CMA. For both pairs of partner symmetries, using Lie equations, we introduce explicitly group parameters as additional variables, replacing symmetry characteristics and their complex conjugates by derivatives of the unknown with respect to group parameters. We study the resulting system of six equations in the eight-dimensional space, that includes CMA, four equations of the recursion between partner symmetries and one integrability condition of this system. We use point symmetries of this extended system for performing its symmetry reduction with respect to group parameters that facilitates solving the extended system. This procedure does not imply a reduction in the number of physical variables and hence we end up with orbits of non-invariant solutions of CMA, generated by one partner symmetry, not used in the reduction. These solutions are determined by six linear equations with constant coefficients in the five-dimensional space which are obtained by a three-dimensional Legendre transformation of the reduced extended system. We present algebraic and exponential examples of such solutions that govern Legendre-transformed Ricci-flat Kähler metrics with no Killing vectors. A similar procedure is briefly outlined for Husain equation.

On systems having Poincaré and Galileo symmetry

International Nuclear Information System (INIS)

Holland, Peter

2014-01-01

Using the wave equation in d≥1 space dimensions it is illustrated how dynamical equations may be simultaneously Poincaré and Galileo covariant with respect to different sets of independent variables. This provides a method to obtain dynamics-dependent representations of the kinematical symmetries. When the field is a displacement function both symmetries have a physical interpretation. For d=1 the Lorentz structure is utilized to reveal hitherto unnoticed features of the non-relativistic Chaplygin gas including a relativistic structure with a limiting case that exhibits the Carroll group, and field-dependent symmetries and associated Noether charges. The Lorentz transformations of the potentials naturally associated with the Chaplygin system are given. These results prompt the search for further symmetries and it is shown that the Chaplygin equations support a nonlinear superposition principle. A known spacetime mixing symmetry is shown to decompose into label-time and superposition symmetries. It is shown that a quantum mechanical system in a stationary state behaves as a Chaplygin gas. The extension to d>1 is used to illustrate how the physical significance of the dual symmetries is contingent on the context by showing that Maxwell’s equations exhibit an exact Galileo covariant formulation where Lorentz and gauge transformations are represented by field-dependent symmetries. A natural conceptual and formal framework is provided by the Lagrangian and Eulerian pictures of continuum mechanics

Tracking gauge symmetry factorizability on intervals

International Nuclear Information System (INIS)

Ngoc-Khanh Tran

2006-01-01

We track the gauge symmetry breaking pattern by boundary conditions on fifth and higher-dimensional intervals. It is found that, with Dirichlet-Neumann boundary conditions, the Kaluza-Klein decomposition in five-dimension for arbitrary gauge group can always be factorized into that for separate subsets of at most two gauge symmetries, and so is completely solvable. Accordingly, we present a simple and systematic geometric method to unambiguously identify the gauge breaking/mixing content by general set of Dirichlet-Neumann boundary conditions. We then formulate a limit theorem on gauge symmetry factorizability to recapitulate this interesting feature. Albeit the breaking/mixing, a particularly simple check of orthogonality and normalization of fields' modes in effective 4-dim picture is explicitly obtained. An interesting chained-mixing of gauge symmetries in higher dimensions by Dirichlet-Neumann boundary conditions is also explicitly constructed. This study has direct applications to higgsless/GUT model building

Identification of intrinsic catalytic activity for electrochemical reduction of water molecules to generate hydrogen

KAUST Repository

Shinagawa, Tatsuya

2015-01-01

Insufficient hydronium ion activities at near-neutral pH and under unbuffered conditions induce diffusion-limited currents for hydrogen evolution, followed by a reaction with water molecules to generate hydrogen at elevated potentials. The observed constant current behaviors at near neutral pH reflect the intrinsic electrocatalytic reactivity of the metal electrodes for water reduction. This journal is © the Owner Societies.

Acoustic reflection log in transversely isotropic formations

Science.gov (United States)

Ronquillo Jarillo, G.; Markova, I.; Markov, M.

2018-01-01

We have calculated the waveforms of sonic reflection logging for a fluid-filled borehole located in a transversely isotropic rock. Calculations have been performed for an acoustic impulse source with the characteristic frequency of tens of kilohertz that is considerably less than the frequencies of acoustic borehole imaging tools. It is assumed that the borehole axis coincides with the axis of symmetry of the transversely isotropic rock. It was shown that the reflected wave was excited most efficiently at resonant frequencies. These frequencies are close to the frequencies of oscillations of a fluid column located in an absolutely rigid hollow cylinder. We have shown that the acoustic reverberation is controlled by the acoustic impedance of the rock Z = Vphρs for fixed parameters of the borehole fluid, where Vph is the velocity of horizontally propagating P-wave; ρs is the rock density. The methods of waveform processing to determine the parameters characterizing the reflected wave have been discussed.

X-ray reflectivity study of thermal capillary waves on liquid surfaces

International Nuclear Information System (INIS)

Ocko, B.M.; Wu, X.Z.; Sirota, E.B.; Sinha, S.K.; Deutsch, M.

1994-01-01

X-ray reflectivity measurements have been carried out at the liquid/vapor interface of normal alkanes. The reflectivities over a large temperature range of different chain lengths (C20 and C36) provide a critical test of the various capillary wave models. Our data are most consistent with the hybrid model which allows for a molecular size dependent cutoff q max for the capillary waves and an intrinsic interface width σ 0

Some general constraints on identical band symmetries

International Nuclear Information System (INIS)

Guidry, M.W.; Strayer, M.R.; Wu, C.; Feng, D.H.

1993-01-01

We argue on general grounds that nearly identical bands observed for superdeformation and less frequently for normal deformation must be explicable in terms of a symmetry having a microscopic basis. We assume that the unknown symmetry is associated with a Lie algebra generated by terms bilinear in fermion creation and annihilation operators. Observed features of these bands and the general properties of Lie groups are then used to place constraints on acceptable algebras. Additional constraints are placed by assuming that the collective spectrum is associated with a dynamical symmetry, and examining the subgroup structure required by phenomenology. We observe that requisite symmetry cannot be unitary, and that the simplest known group structures consistent with these minimal criteria are associated with the Ginocchio algebras employed in the fermion dynamical symmetry model. However, our arguments are general in nature, and we propose that they imply model-independent constraints on any candidate explanation for identical bands

Boson symmetries in exotic N∼Z nuclei

International Nuclear Information System (INIS)

Van Isacker, P.

1996-01-01

Heavy N ∼ Z nuclei provide an ideal testing ground for various symmetries such as isospin and isospin-spin or SU(4) symmetry. The associated quantum numbers of orbital angular momentum L, isospin T, spin S AND SU(4) labels (λμnu)can be carried over onto appropriate versions of the interacting boson model (IBM). Symmetries allow to relate the boson model to the shell model; the composite character of the bosons permits a broader application of the concept of symmetry in IBM. The discussion then focuses on IBM-3 (which includes T = 1 bosons only) and IBM-4 (with T = 0 and T = 1 bosons). A connection is established between them which relies on an IBM-4 classification that breaks Wigner's SU(4) symmetry. The resulting generalised IBM-4 is relevant for studying the competition between T = 0 and T = 1 pairing in N ∼ Z nuclei. An application to odd-odd self-conjugate nuclei is presented. (author). 20 refs., 2 tabs

Recurrence and symmetry of time series: Application to transition detection

International Nuclear Information System (INIS)

Girault, Jean-Marc

2015-01-01

Highlights: •A new theoretical framework based on the symmetry concept is proposed. •Four types of symmetry present in any time series were analyzed. •New descriptors make possible the analysis of regime changes in logistic systems. •Chaos–chaos, chaos–periodic, symmetry-breaking, symmetry-increasing bifurcations can be detected. -- Abstract: The study of transitions in low dimensional, nonlinear dynamical systems is a complex problem for which there is not yet a simple, global numerical method able to detect chaos–chaos, chaos–periodic bifurcations and symmetry-breaking, symmetry-increasing bifurcations. We present here for the first time a general framework focusing on the symmetry concept of time series that at the same time reveals new kinds of recurrence. We propose several numerical tools based on the symmetry concept allowing both the qualification and quantification of different kinds of possible symmetry. By using several examples based on periodic symmetrical time series and on logistic and cubic maps, we show that it is possible with simple numerical tools to detect a large number of bifurcations of chaos–chaos, chaos–periodic, broken symmetry and increased symmetry types

QT Adaptation and Intrinsic QT Variability in Congenital Long QT Syndrome.

Science.gov (United States)

Seethala, Srikanth; Singh, Prabhpreet; Shusterman, Vladimir; Ribe, Margareth; Haugaa, Kristina H; Němec, Jan

2015-12-16

Increased variability of QT interval (QTV) has been linked to arrhythmias in animal experiments and multiple clinical situations. Congenital long QT syndrome (LQTS), a pure repolarization disease, may provide important information on the relationship between delayed repolarization and QTV. Twenty-four-hour Holter monitor tracings from 78 genotyped congenital LQTS patients (52 females; 51 LQT1, 23 LQT2, 2 LQT5, 2 JLN, 27 symptomatic; age, 35.2±12.3 years) were evaluated with computer-assisted annotation of RR and QT intervals. Several models of RR-QT relationship were tested in all patients. A model assuming exponential decrease of past RR interval contributions to QT duration with 60-second time constant provided the best data fit. This model was used to calculate QTc and residual "intrinsic" QTV, which cannot be explained by heart rate change. The intrinsic QTV was higher in patients with long QTc (r=0.68; Padaptation to heart rate changes occurs with time constant ≈60 seconds, similar to results reported in control subjects. Intrinsic QTV correlates with the degree of repolarization delay and might reflect action potential instability observed in animal models of LQTS. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

At the origins of mass: elementary particles and fundamental symmetries

International Nuclear Information System (INIS)

Iliopoulos, Jean; Englert, Francois

2015-01-01

After a brief recall of the history of cosmology, the author proposes an overview of the different symmetries (symmetries in space and in time, internal symmetries, local or gauge symmetries), describes the mass issue (gauge interactions, quarks and leptons as matter mass constituents, chirality), addresses the spontaneous symmetry breaking (the Curie theorem, spontaneous symmetry breaking in classical physics and in quantum physics, the Goldstone theorem, spontaneous symmetry breaking in presence of gauge interactions), presents the standard theory (electromagnetic and weak interactions, strong interactions, relationship with experiment). An appendix presents elementary particles, and notably reports the story of the neutrino

On discrete symmetries for a whole Abelian model

International Nuclear Information System (INIS)

Chauca, J.; Doria, R.

2012-01-01

Considering the whole concept applied to gauge theory a nonlinear abelian model is derived. A next step is to understand on the model properties. At this work, it will be devoted to discrete symmetries. For this, we will work based in two fields reference systems. This whole gauge symmetry allows to be analyzed through different sets which are the constructor basis {D μ ,X i μ } and the physical basis {G μI }. Taking as fields reference system the diagonalized spin-1 sector, P, C, T and PCT symmetries are analyzed. They show that under this systemic model there are conservation laws driven for the parts and for the whole. It develops the meaning of whole-parity, field-parity and so on. However it is the whole symmetry that rules. This means that usually forbidden particles as pseudovector photons can be introduced through such whole abelian system. As result, one notices that the fields whole {G μI } manifest a quanta diversity. It involves particles with different spins, masses and discrete quantum numbers under a same gauge symmetry. It says that without violating PCT symmetry different possibilities on discrete symmetries can be accommodated.

Rotational Symmetry Breaking in Baby Skyrme Models

Science.gov (United States)

Karliner, Marek; Hen, Itay

We discuss one of the most interesting phenomena exhibited by baby skyrmions - breaking of rotational symmetry. The topics we will deal with here include the appearance of rotational symmetry breaking in the static solutions of baby Skyrme models, both in flat as well as in curved spaces, the zero-temperature crystalline structure of baby skyrmions, and finally, the appearance of spontaneous breaking of rotational symmetry in rotating baby skyrmions.

Higher order Lie-Baecklund symmetries of evolution equations

International Nuclear Information System (INIS)

Roy Chowdhury, A.; Roy Chowdhury, K.; Paul, S.

1983-10-01

We have considered in detail the analysis of higher order Lie-Baecklund symmetries for some representative nonlinear evolution equations. Until now all such symmetry analyses have been restricted only to the first order of the infinitesimal parameter. But the existence of Baecklund transformation (which can be shown to be an overall sum of higher order Lie-Baecklund symmetries) makes it necessary to search for such higher order Lie-Baecklund symmetries directly without taking recourse to the Baecklund transformation or inverse scattering technique. (author)

The Nature of the Chemical Process. 1. Symmetry Evolution – Revised Information Theory, Similarity Principle and Ugly Symmetry

Directory of Open Access Journals (Sweden)

Shu-Kun Lin

2001-03-01

Full Text Available Abstract: Symmetry is a measure of indistinguishability. Similarity is a continuous measure of imperfect symmetry. Lewis' remark that “gain of entropy means loss of information” defines the relationship of entropy and information. Three laws of information theory have been proposed. Labeling by introducing nonsymmetry and formatting by introducing symmetry are defined. The function L ( L=lnw, w is the number of microstates, or the sum of entropy and information, L=S+I of the universe is a constant (the first law of information theory. The entropy S of the universe tends toward a maximum (the second law law of information theory. For a perfect symmetric static structure, the information is zero and the static entropy is the maximum (the third law law of information theory. Based on the Gibbs inequality and the second law of the revised information theory we have proved the similarity principle (a continuous higher similarity−higher entropy relation after the rejection of the Gibbs paradox and proved the Curie-Rosen symmetry principle (a higher symmetry−higher stability relation as a special case of the similarity principle. The principles of information minimization and potential energy minimization are compared. Entropy is the degree of symmetry and information is the degree of nonsymmetry. There are two kinds of symmetries: dynamic and static symmetries. Any kind of symmetry will define an entropy and, corresponding to the dynamic and static symmetries, there are static entropy and dynamic entropy. Entropy in thermodynamics is a special kind of dynamic entropy. Any spontaneous process will evolve towards the highest possible symmetry, either dynamic or static or both. Therefore the revised information theory can be applied to characterizing all kinds of structural stability and process spontaneity. Some examples in chemical physics have been given. Spontaneous processes of all kinds of molecular

Conformal symmetry in quantum finance

International Nuclear Information System (INIS)

Romero, Juan M; Lavana, Ulises; Miranda, Elio Martínez

2014-01-01

The quantum finance symmetries are studied. In order to do this, the one dimensional free non-relativistic particle and its symmetries are revisited and the particle mass is identified as the inverse of square of the volatility. Furthermore, using financial variables, a Schrödinger algebra representation is constructed. In addition, it is shown that the operators of this last representation are not hermitian and not conserved.

Symmetries of Maldacena-Wilson loops from integrable string theory

International Nuclear Information System (INIS)

Muenkler, Hagen

2017-01-01

This thesis discusses hidden symmetries within N=4 supersymmetric Yang-Mills theory or its AdS/CFT dual, string theory in AdS 5 x S 5 . Here, we focus on the Maldacena-Wilson loop, which is a suitable object for this study since its vacuum expectation value is finite for smooth contours and the conjectured duality to scattering amplitudes provides a conceptual path to transfer its symmetries to other observables. Its strong-coupling description via minimal surfaces in AdS 5 allows to construct the symmetries from the integrability of the underlying classical string theory. This approach has been utilized before to derive a strong-coupling Yangian symmetry of the Maldacena-Wilson loop and describe equiareal deformations of minimal surfaces in AdS 3 . These two findings are connected and extended in the present thesis. In order to discuss the symmetries systematically, we first discuss the symmetry structure of the underlying string model. The discussion can be generalized to the discussion of generic symmetric space models. For these, we find that the symmetry which generates the equiareal deformations of minimal surfaces in AdS 3 has a central role in the symmetry structure of the model: It acts as a raising operator on the infinite tower of conserved charges, thus generating the spectral parameter, and can be employed to construct all symmetry variations from the global symmetry of the model. It is thus referred to as the master symmetry of symmetric space models. Additionally, the algebra of the symmetry variations and the conserved charges is worked out. For the concrete case of minimal surfaces in AdS 5 , we discuss the deformation of the four-cusp solution, which provides the dual description of the four-gluon scattering amplitude. This marks the first step toward transferring the master symmetry to scattering amplitudes. Moreover, we compute the master and Yangian symmetry variations of generic, smooth boundary curves. The results leads to a coupling

Symmetries of Maldacena-Wilson loops from integrable string theory

Energy Technology Data Exchange (ETDEWEB)

Muenkler, Hagen

2017-09-11

This thesis discusses hidden symmetries within N=4 supersymmetric Yang-Mills theory or its AdS/CFT dual, string theory in AdS{sub 5} x S{sup 5}. Here, we focus on the Maldacena-Wilson loop, which is a suitable object for this study since its vacuum expectation value is finite for smooth contours and the conjectured duality to scattering amplitudes provides a conceptual path to transfer its symmetries to other observables. Its strong-coupling description via minimal surfaces in AdS{sub 5} allows to construct the symmetries from the integrability of the underlying classical string theory. This approach has been utilized before to derive a strong-coupling Yangian symmetry of the Maldacena-Wilson loop and describe equiareal deformations of minimal surfaces in AdS{sub 3}. These two findings are connected and extended in the present thesis. In order to discuss the symmetries systematically, we first discuss the symmetry structure of the underlying string model. The discussion can be generalized to the discussion of generic symmetric space models. For these, we find that the symmetry which generates the equiareal deformations of minimal surfaces in AdS{sub 3} has a central role in the symmetry structure of the model: It acts as a raising operator on the infinite tower of conserved charges, thus generating the spectral parameter, and can be employed to construct all symmetry variations from the global symmetry of the model. It is thus referred to as the master symmetry of symmetric space models. Additionally, the algebra of the symmetry variations and the conserved charges is worked out. For the concrete case of minimal surfaces in AdS{sub 5}, we discuss the deformation of the four-cusp solution, which provides the dual description of the four-gluon scattering amplitude. This marks the first step toward transferring the master symmetry to scattering amplitudes. Moreover, we compute the master and Yangian symmetry variations of generic, smooth boundary curves. The results

Self-isospectrality, mirror symmetry, and exotic nonlinear supersymmetry

International Nuclear Information System (INIS)

Plyushchay, Mikhail S.; Nieto, Luis-Miguel

2010-01-01

We study supersymmetry of a self-isospectral one-gap Poeschl-Teller system in the light of a mirror symmetry that is based on spatial and shift reflections. The revealed exotic, partially broken, nonlinear supersymmetry admits seven alternatives for a grading operator. One of its local, first order supercharges may be identified as a Hamiltonian of an associated one-gap, nonperiodic Bogoliubov-de Gennes system. The latter possesses a nonlinear supersymmetric structure, in which any of the three nonlocal generators of a Clifford algebra may be chosen as the grading operator. We find that the supersymmetry generators for both systems are the Darboux-dressed integrals of a free spin-1/2 particle in the Schroedinger picture, or of a free massive Dirac particle. Nonlocal Foldy-Wouthuysen transformations are shown to be involved in the supersymmetric structure.

Quantum restoration of broken symmetry in onedimensional loop ...

Indian Academy of Sciences (India)

Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 6. Quantum restoration of broken symmetry in ... Keywords. Non-local transformation; broken symmetry; sine-Gordon; sech interaction. ... A specific type of classically broken symmetry is restored in quantum theory. One-dimensional sine-Gordon system and ...

Spacetime symmetries and topology in bimetric relativity

Science.gov (United States)

Torsello, Francesco; Kocic, Mikica; Högâs, Marcus; Mörtsell, Edvard

2018-04-01

We explore spacetime symmetries and topologies of the two metric sectors in Hassan-Rosen bimetric theory. We show that, in vacuum, the two sectors can either share or have separate spacetime symmetries. If stress-energy tensors are present, a third case can arise, with different spacetime symmetries within the same sector. This raises the question of the best definition of spacetime symmetry in Hassan-Rosen bimetric theory. We emphasize the possibility of imposing ansatzes and looking for solutions having different Killing vector fields or different isometries in the two sectors, which has gained little attention so far. We also point out that the topology of spacetime imposes a constraint on possible metric combinations.

Charge-symmetry-breaking nucleon form factors

Energy Technology Data Exchange (ETDEWEB)

Kubis, Bastian, E-mail: kubis@hiskp.uni-bonn.de [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics (Germany)

2011-11-15

A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon's strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for {sup 4}He.

Space-time and Local Gauge Symmetries

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 2. Symmetries of Particle Physics: Space-time and Local Gauge Symmetries. Sourendu Gupta. General Article Volume 6 Issue 2 February 2001 pp 29-38. Fulltext. Click here to view fulltext PDF. Permanent link:

Discrete R-symmetries and anomaly universality in heterotic orbifolds

Energy Technology Data Exchange (ETDEWEB)

Bizet, Nana G. Cabo [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear,Calle 30, esq.a 5ta Ave, Miramar, 6122 La Habana (Cuba); Kobayashi, Tatsuo [Department of Physics, Kyoto University,Kyoto 606-8502 (Japan); Peña, Damián K. Mayorga [Bethe Center for Theoretical Physics and Physikalisches Institut der Universität Bonn,Nussallee 12, 53115 Bonn (Germany); Parameswaran, Susha L. [Department of Mathematics and Physics, Leibniz Universität Hannover,Welfengarten 1, 30167 Hannover (Germany); Schmitz, Matthias [Bethe Center for Theoretical Physics and Physikalisches Institut der Universität Bonn,Nussallee 12, 53115 Bonn (Germany); Zavala, Ivonne [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands)

2014-02-24

We study discrete R-symmetries, which appear in the 4D low energy effective field theory derived from heterotic orbifold models. We derive the R-symmetries directly from the geometrical symmetries of the orbifolds. In particular, we obtain the corresponding R-charges by requiring that the couplings be invariant under these symmetries. This allows for a more general treatment than the explicit computations of correlation functions made previously by the authors, including models with discrete Wilson lines, and orbifold symmetries beyond plane-by-plane rotational invariance. The R-charges obtained in this manner differ from those derived in earlier explicit computations. We study the anomalies associated with these R-symmetries, and comment on the results.

Residual symmetries in the presence of an EM background

International Nuclear Information System (INIS)

Carrion, H.L.; Rojas, M.; Toppan, F.

2002-08-01

The symmetry algebra of a QFT in the presence of an external EM background (named 'residual symmetry') is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra is isomorphic to u(1) +P c (2), with P c (2) the centrally extended 2-dimensional Poincare algebra. In D = 4 dimension the generic residual symmetry algebra is given by a seven-dimensional solvable Lie algebra which is explicitly computed. residual symmetry algebras are also computed for specific non-constant EM backgrounds. (author)

Residual symmetries in the presence of an EM background

Energy Technology Data Exchange (ETDEWEB)

Rojas Leyva, Moises Porfirio; Salazar, Hector Leny Carrion; Toppan, Francesco [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: mrojas, hleny, toppan@cbpf.br

2001-07-01

The symmetry algebra of a QFT in the presence of an external EM background (named 'residual symmetry') is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra is isomorphic to u(1) + P{sub c} (2) the centrally extended 2-dimensional Poincare algebra. In D=4 dimensions the generic residual symmetry algebra is given by a 7 dimensional solvable Lie algebra which is explicitly computed. Residual symmetry algebras are also computed for specific non-constant EM backgrounds. (author)

Interdependence of different symmetry energy elements

Science.gov (United States)

Mondal, C.; Agrawal, B. K.; De, J. N.; Samaddar, S. K.; Centelles, M.; Viñas, X.

2017-08-01

Relations between the nuclear symmetry energy coefficient and its density derivatives are derived. The relations hold for a class of interactions with quadratic momentum dependence and a power-law density dependence. The structural connection between the different symmetry energy elements as obtained seems to be followed by almost all reasonable nuclear energy density functionals, both relativistic and nonrelativistic, suggesting a universality in the correlation structure. This, coupled with known values of some well-accepted constants related to nuclear matter, helps in constraining values of different density derivatives of the nuclear symmetry energy, shedding light on the isovector part of the nuclear interaction.

The zonal satellite problem. III Symmetries

Directory of Open Access Journals (Sweden)

Mioc V.

2002-01-01

Full Text Available The two-body problem associated with a force field described by a potential of the form U =Sum(k=1,n ak/rk (r = distance between particles, ak = real parameters is resumed from the only standpoint of symmetries. Such symmetries, expressed in Hamiltonian coordinates, or in standard polar coordinates, are recovered for McGehee-type coordinates of both collision-blow-up and infinity-blow-up kind. They form diffeomorphic commutative groups endowed with a Boolean structure. Expressed in Levi-Civita’s coordinates, the problem exhibits a larger group of symmetries, also commutative and presenting a Boolean structure.

Discrete symmetries and de Sitter spacetime

Energy Technology Data Exchange (ETDEWEB)

Cotăescu, Ion I., E-mail: gpascu@physics.uvt.ro; Pascu, Gabriel, E-mail: gpascu@physics.uvt.ro [West University of Timişoara, V. Pârvan Ave. 4, RO-300223 Timişoara (Romania)

2014-11-24

Aspects of the ambiguity in defining quantum modes on de Sitter spacetime using a commuting system composed only of differential operators are discussed. Discrete symmetries and their actions on the wavefunction in commonly used coordinate charts are reviewed. It is argued that the system of commuting operators can be supplemented by requiring the invariance of the wavefunction to combined discrete symmetries- a criterion which selects a single state out of the α-vacuum family. Two such members of this family are singled out by particular combined discrete symmetries- states between which exists a well-known thermality relation.

Up-down symmetry of the turbulent transport of toroidal angular momentum in tokamaks

International Nuclear Information System (INIS)

Parra, Felix I.; Barnes, Michael; Peeters, Arthur G.

2011-01-01

Two symmetries of the local nonlinear δf gyrokinetic system of equations in tokamaks in the high flow regime are presented. The turbulent transport of toroidal angular momentum changes sign under an up-down reflection of the tokamak and a sign change of both the rotation and the rotation shear. Thus, the turbulent transport of toroidal angular momentum must vanish for up-down symmetric tokamaks in the absence of both rotation and rotation shear. This has important implications for the modeling of spontaneous rotation.

Deconfined Quantum Critical Points: Symmetries and Dualities

Directory of Open Access Journals (Sweden)

Chong Wang

2017-09-01

Full Text Available The deconfined quantum critical point (QCP, separating the Néel and valence bond solid phases in a 2D antiferromagnet, was proposed as an example of (2+1D criticality fundamentally different from standard Landau-Ginzburg-Wilson-Fisher criticality. In this work, we present multiple equivalent descriptions of deconfined QCPs, and use these to address the possibility of enlarged emergent symmetries in the low-energy limit. The easy-plane deconfined QCP, besides its previously discussed self-duality, is dual to N_{f}=2 fermionic quantum electrodynamics, which has its own self-duality and hence may have an O(4×Z_{2}^{T} symmetry. We propose several dualities for the deconfined QCP with SU(2 spin symmetry which together make natural the emergence of a previously suggested SO(5 symmetry rotating the Néel and valence bond solid orders. These emergent symmetries are implemented anomalously. The associated infrared theories can also be viewed as surface descriptions of (3+1D topological paramagnets, giving further insight into the dualities. We describe a number of numerical tests of these dualities. We also discuss the possibility of “pseudocritical” behavior for deconfined critical points, and the meaning of the dualities and emergent symmetries in such a scenario.

Symmetry and Asymmetry Level Measures

Directory of Open Access Journals (Sweden)

Angel Garrido

2010-04-01

Full Text Available Usually, Symmetry and Asymmetry are considered as two opposite sides of a coin: an object is either totally symmetric, or totally asymmetric, relative to pattern objects. Intermediate situations of partial symmetry or partial asymmetry are not considered. But this dichotomy on the classification lacks of a necessary and realistic gradation. For this reason, it is convenient to introduce "shade regions", modulating the degree of Symmetry (a fuzzy concept. Here, we will analyze the Asymmetry problem by successive attempts of description and by the introduction of the Asymmetry Level Function, as a new Normal Fuzzy Measure. Our results (both Theorems and Corollaries suppose to be some new and original contributions to such very active and interesting field of research. Previously, we proceed to the analysis of the state of art.

Hidden Symmetries of Stochastic Models

Directory of Open Access Journals (Sweden)

Boyka Aneva

2007-05-01

Full Text Available In the matrix product states approach to $n$ species diffusion processes the stationary probability distribution is expressed as a matrix product state with respect to a quadratic algebra determined by the dynamics of the process. The quadratic algebra defines a noncommutative space with a $SU_q(n$ quantum group action as its symmetry. Boundary processes amount to the appearance of parameter dependent linear terms in the algebraic relations and lead to a reduction of the $SU_q(n$ symmetry. We argue that the boundary operators of the asymmetric simple exclusion process generate a tridiagonal algebra whose irriducible representations are expressed in terms of the Askey-Wilson polynomials. The Askey-Wilson algebra arises as a symmetry of the boundary problem and allows to solve the model exactly.

From anomalies of finite symmetries to heterotic GUTs

Science.gov (United States)

Vaudrevange, Patrick K. S.

2017-11-01

We review the role of finite symmetries for particle physics with special emphasis on discrete anomalies and on their possible origin from extra dimensions. Then, we apply our knowledge on finite symmetries to the problematic proton decay operators of various mass-dimensions, focusing on ℤ4R , i.e. a special R-symmetry of order 4. We show that this ℤ4R symmetry can naturally originate from extra dimensions as a discrete remnant of higher-dimensional Lorentz symmetry. Finally, in order to obtain a unified picture from the heterotic string theory we discuss grand unified theories (GUTs) in extra dimensions compactified on ℤ2 × ℤ2 orbifolds and show how proton decay operators can be suppressed in a certain class of orbifolds.

Symmetry Properties of Potentiometric Titration Curves.

Science.gov (United States)

Macca, Carlo; Bombi, G. Giorgio

1983-01-01

Demonstrates how the symmetry properties of titration curves can be efficiently and rigorously treated by means of a simple method, assisted by the use of logarithmic diagrams. Discusses the symmetry properties of several typical titration curves, comparing the graphical approach and an explicit mathematical treatment. (Author/JM)

Threefold rotational symmetry in hexagonally shaped core-shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging.

Science.gov (United States)

Davtyan, Arman; Krause, Thilo; Kriegner, Dominik; Al-Hassan, Ali; Bahrami, Danial; Mostafavi Kashani, Seyed Mohammad; Lewis, Ryan B; Küpers, Hanno; Tahraoui, Abbes; Geelhaar, Lutz; Hanke, Michael; Leake, Steven John; Loffeld, Otmar; Pietsch, Ullrich

2017-06-01

Coherent X-ray diffraction imaging at symmetric hhh Bragg reflections was used to resolve the structure of GaAs/In 0.15 Ga 0.85 As/GaAs core-shell-shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct the lost phase information. It is demonstrated that the structure of the core-shell-shell nanowire can be identified by means of phase contrast. Interestingly, it is found that both scattered intensity in the (111) plane and the reconstructed scattering phase show an additional threefold symmetry superimposed with the shape function of the investigated hexagonal nanowires. In order to find the origin of this threefold symmetry, elasticity calculations were performed using the finite element method and subsequent kinematic diffraction simulations. These suggest that a non-hexagonal (In,Ga)As shell covering the hexagonal GaAs core might be responsible for the observation.

Reflection of P and SV waves at the free surface of a monoclinic ...

Indian Academy of Sciences (India)

R.Narasimhan(krishtel emaging)1461 1996 Oct 15 13:05:22

The propagation of plane waves in an anisotropic elastic medium possessing monoclinic symmetry is discussed. The expressions for ... Keywords. Anisotropic medium; elastic waves; monoclinic half-space; reflection coefficients. Proc. Indian Acad. Sci. ...... In contrast, for C < 0, the angle of reflec- tion is less than the angle of ...

On the factorial and construct validity of the Intrinsic Motivation Inventory: conceptual and operational concerns.

Science.gov (United States)

Markland, D; Hardy, L

1997-03-01

The Intrinsic Motivation Inventory (IMI) has been gaining acceptance in the sport and exercise domain since the publication of research by McAuley, Duncan, and Tammen (1989) and McAuley, Wraith, and Duncan (1991), which reported confirmatory support for the factorial validity of a hierarchical model of intrinsic motivation. Authors of the present study argue that the results of these studies did not conclusively support the hierarchical model and that the model did not accurately reflect the tenets of cognitive evaluation theory (Deci & Ryan, 1985) from which the IMI is drawn. It is also argued that a measure of perceived locus of causality is required to model intrinsic motivation properly. The development of a perceived locus of causality for exercise scale is described, and alternative models, in which perceived competence and perceived locus of causality are held to have causal influences on intrinsic motivation, are compared with an oblique confirmatory factor analytic model in which the constructs are held at the same conceptual level. Structural equation modeling showed support for a causal model in which perceived locus of causality mediates the effects of perceived competence on pressure-tension, interest-enjoyment, and effort-importance. It is argued that conceptual and operational problems with the IMI, as currently used, should be addressed before it becomes established as the instrument of choice for assessing levels of intrinsic motivation.

Symmetry and physical properties of crystals

CERN Document Server

Malgrange, Cécile; Schlenker, Michel

2014-01-01

Crystals are everywhere, from natural crystals (minerals) through the semiconductors and magnetic materials in electronic devices and computers or piezoelectric resonators at the heart of our quartz watches to electro-optical devices. Understanding them in depth is essential both for pure research and for their applications. This book provides a clear, thorough presentation of their symmetry, both at the microscopic space-group level and the macroscopic point-group level. The implications of the symmetry of crystals for their physical properties are then presented, together with their mathematical description in terms of tensors. The conditions on the symmetry of a crystal for a given property to exist then become clear, as does the symmetry of the property. The geometrical representation of tensor quantities or properties is presented, and its use in determining important relationships emphasized. An original feature of this book is that most chapters include exercises with complete solutions. This all...

Effect of orbital symmetry on the anisotropic superexchange interaction

International Nuclear Information System (INIS)

Kim, Beom Hyun; Min, B I

2011-01-01

Employing the microscopic superexchange model incorporating the effect of spin-orbit interaction, we have investigated the Dzyaloshinsky-Moriya (DM) interaction in perovskite transition-metal (TM) oxides and explored the interplay between the DM interaction and the TM-3d orbital symmetry. For d 3 and d 5 systems with isotropic orbital symmetry, the DM vectors are well described by a simple symmetry analysis considering only the bond geometry. In contrast, the DM interaction for d 4 systems with anisotropic orbital symmetry shows slightly different behavior, which does not obey simple symmetry analysis. The direction as well as the strength of the DM vector varies depending on the occupied orbital shape. We have understood this behavior based on the orbital symmetry induced by local crystal field variation.

Residual symmetries in the presence of an EM background

Energy Technology Data Exchange (ETDEWEB)

Carrion, H.L.; Rojas, M.; Toppan, F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: hleny@cbpf.br; mrojas@cbpf.br; toppan@cbpf.br

2002-08-01

The symmetry algebra of a QFT in the presence of an external EM background (named 'residual symmetry') is investigated within a Lie-algebraic, model independent scheme. Some results previously encountered in the literature are here extended. In particular we compute the symmetry algebra for a constant EM background in D = 3 and D = 4 dimensions. In D = 3 dimensions the residual symmetry algebra is isomorphic to u(1) +P{sub c}(2), with P{sub c}(2) the centrally extended 2-dimensional Poincare algebra. In D = 4 dimension the generic residual symmetry algebra is given by a seven-dimensional solvable Lie algebra which is explicitly computed. residual symmetry algebras are also computed for specific non-constant EM backgrounds. (author)

Shifted intrinsic connectivity of central executive and salience network in borderline personality disorder

Directory of Open Access Journals (Sweden)

Anselm eDoll

2013-10-01

Full Text Available Borderline personality disorder (BPD is characterized by stable instability of emotions and behavior and their regulation. This emotional and behavioral instability corresponds with a neurocognitive triple network model of psychopathology, which suggests that aberrant emotional saliency and cognitive control is associated with aberrant interaction across three intrinsic connectivity networks (ICN (i.e. the salience, default mode, and central executive network, SN, DMN, CEN. The objective of the current study was to investigate whether and how such triple network intrinsic functional connectivity (iFC is changed in patients with BPD. We acquired resting-state functional magnetic resonance imaging (rs-fMRI data from fourteen patients with BPD and sixteen healthy controls (HC. High-model order independent component analysis (ICA was used to extract spatiotemporal patterns of ongoing, coherent blood-oxygen-level-dependent (BOLD signal fluctuations from rs-fMRI data. Main outcome measures were iFC within networks (intra-iFC and between networks (i.e. network time course correlation inter-iFC.Aberrant intra-iFC was found in patients’ DMN, SN, and CEN, consistent with previous findings. While patients’ inter-iFC of the CEN was decreased, inter-iFC of the SN was increased. In particular, a balance index reflecting the relationship of CEN-and SN-inter-iFC across networks was strongly shifted from CEN to SN connectivity in patients. Results provide first preliminary evidence for aberrant triple network intrinsic functional connectivity in BPD. Our data suggest a shift of inter-network iFC from networks involved in cognitive control to those of emotion-related activity in BPD, potentially reflecting the persistent instability of emotion regulation in patients.

Sub-color and leptoquark-quark symmetry

International Nuclear Information System (INIS)

Nakamura, Fumihiko

1982-01-01

On the basis of leptoquark-quark symmetry, we propose possible models, in which leptons and gauge bosons are constructed is SU(2) symmetry. In one of the cases, the subcolor is introduced as the quantum number of the leptoquark. Then the possibility of baryon decay is discussed. (author)

Symmetry and fermion degeneracy on a lattice

International Nuclear Information System (INIS)

Raszillier, H.

1982-03-01

In this paper we consider the general form of finite difference approximation to the Dirac (Weyl) Hamiltonian on a lattice and investigate systematically the dependence on symmetry of the number of particles described by it. Our result is, that to a symmetry - expressed by a crystallographic space group - there corresponds a minimal number of particles, which are associated to prescribed points of momentum space (the unit cell of the reciprocal lattice). For convenience of the reader we show, using the existing detailed descriptions of space groups, how these results look for all the relevant (symmorphic) symmetry groups. Only for lattice Hamiltonians with a momentum dependent mass term can this degeneracy be reduced and even eliminated without reducing the symmetry. (orig./HSI)

Charged tensor matter fields and Lorentz symmetry violation via spontaneous symmetry breaking

International Nuclear Information System (INIS)

Colatto, L.P.; Penna, A.L.A.; Santos, W.C.

2003-10-01

We consider a model with a charged vector field along with a Cremmer-Scherk-Kalb-Ramond (CSKR) matter field coupled to a U(1) gauge potential. We obtain a natural Lorentz symmetry violation due to the local U(1) spontaneous symmetry breaking mechanism triggered by the imaginary part of the vector matter. The choice of the unitary gauge leads to the decoupling of the gauge-Kr sector from the Higgs-Kr sector. The excitation spectrum is carefully analyzed and the physical modes are identified. We propose an identification of the neutral massive spin-1 Higgs-like field with the massive Z' boson of the so-called mirror matter models. (author)

Generalized symmetry algebras

International Nuclear Information System (INIS)

Dragon, N.

1979-01-01

The possible use of trilinear algebras as symmetry algebras for para-Fermi fields is investigated. The shortcomings of the examples are argued to be a general feature of such generalized algebras. (author)

High-energy symmetries of string theory

International Nuclear Information System (INIS)

Lee Jenchi.

1990-01-01

The author studies the high-energy symmetry structure of string theory corresponding to the massive excitations of the string. These enlarged gauge symmetries are closely related to the existence of zero-norm states in the string spectrum. He has derived these symmetries in the framework of the Hamiltonian version of the first-quantized generalized σ-model formalism. It is conjectured that these infinite space-time symmetry structures could shed light on the finiteness of string perturbation theory. Two interesting phenomena were discovered for these massive states symmetries. One is the inter-'spin' symmetry for the different 'spin' states at each fixed mass level. Specifically, the four physical propagating states with 'spins' up to six of the second massive level of the closed bosonic string are found to form a large gauge multiplet. This is demonstrated by the existence of gauge transformations induced by the type II zero-norm states at this mass level. It is argued that this is a σ-model three loop result for the second massive level and is a general feature for higher massive levels at each fixed mass. The other one is the decoupling of some degenerate positive-norm states. As an example, he explicitly demonstrates that the 'spin' two and scalar physical propagating fields of the third massive level of the open bosonic string are mere gauge artifacts of the higher 'spin' fields at the same mass level. It is conjectured that this phenomenon comes from the well-known ambiguity in defining the positive-norm states due to the existence of zero-norm states in the same Young representation

Broken SU(4) symmetry and new resonance

International Nuclear Information System (INIS)

Ueda, Y.

1975-11-01

Weinberg's spectral function sum rules are modified to accommodate broken symmetry effects of SU(4). With a simple choice of the symmetry-breaking term, the spectral function sum rules yield the observed vector meson mass spectrum as well as sum rules for the e - e + decay rates of vector mesons. In particular, a new mass formula, which can be interpreted as the broken symmetry version of the Schwinger formula, is derived, the agreement with experiments is excellent. (Ueda, Y.)

Quantum group and quantum symmetry

International Nuclear Information System (INIS)

Chang Zhe.

1994-05-01

This is a self-contained review on the theory of quantum group and its applications to modern physics. A brief introduction is given to the Yang-Baxter equation in integrable quantum field theory and lattice statistical physics. The quantum group is primarily introduced as a systematic method for solving the Yang-Baxter equation. Quantum group theory is presented within the framework of quantum double through quantizing Lie bi-algebra. Both the highest weight and the cyclic representations are investigated for the quantum group and emphasis is laid on the new features of representations for q being a root of unity. Quantum symmetries are explored in selected topics of modern physics. For a Hamiltonian system the quantum symmetry is an enlarged symmetry that maintains invariance of equations of motion and allows a deformation of the Hamiltonian and symplectic form. The configuration space of the integrable lattice model is analyzed in terms of the representation theory of quantum group. By means of constructing the Young operators of quantum group, the Schroedinger equation of the model is transformed to be a set of coupled linear equations that can be solved by the standard method. Quantum symmetry of the minimal model and the WZNW model in conformal field theory is a hidden symmetry expressed in terms of screened vertex operators, and has a deep interplay with the Virasoro algebra. In quantum group approach a complete description for vibrating and rotating diatomic molecules is given. The exact selection rules and wave functions are obtained. The Taylor expansion of the analytic formulas of the approach reproduces the famous Dunham expansion. (author). 133 refs, 20 figs

Reflection properties of hydrogen ions at helium irradiated tungsten surfaces

International Nuclear Information System (INIS)

Doi, K; Tawada, Y; Kato, S; Sasao, M; Kenmotsu, T; Wada, M; Lee, H T; Ueda, Y; Tanaka, N; Kisaki, M; Nishiura, M; Matsumoto, Y; Yamaoka, H

2016-01-01

Nanostructured W surfaces prepared by He bombardment exhibit characteristic angular distributions of hydrogen ion reflection upon injection of 1 keV H + beam. A magnetic momentum analyzer that can move in the vacuum chamber has measured the angular dependence of the intensity and the energy of reflected ions. Broader angular distributions were observed for He-irradiated tungsten samples compared with that of the intrinsic polycrystalline W. Both intensity and energy of reflected ions decreased in the following order: the polycrystalline W, the He-bubble containing W, and the fuzz W. Classical trajectory Monte Carlo simulations based on Atomic Collision in Amorphous Target code suggests that lower atom density near the surface can make the reflection coefficients lower due to increasing number of collisions. (paper)

Superdeformations and fermion dynamical symmetries

International Nuclear Information System (INIS)

Wu, Cheng-Li

1990-01-01

In this talk, I will present a link between nuclear collective motions and their underlying fermion dynamical symmetries. In particular, I will focus on the microscopic understanding of deformations. It is shown that the SU 3 of the one major shell fermion dynamical symmetry model (FDSM) is responsible for the physics of low and high spins in normal deformation. For the recently observed phenomena of superdeformation, the physics of the problem dictates a generalization to a supershell structure (SFDSM), which also has an SU 3 fermion dynamical symmetry. Many recently discovered feature of superdeformation are found to be inherent in such an SU 3 symmetry. In both cases the dynamical Pauli effect plays a vital role. A particularly noteworthy discovery from this model is that the superdeformed ground band is not the usual unaligned band but the D-pair aligned (DPA) band, which sharply crosses the excited bands. The existence of such DPA band is a key point to understand many properties of superdeformation. Our studies also poses new experimental challenge. This is particularly interesting since there are now plans to build new and exciting γ-ray detecting systems, like the GAMMASPHERE, which could provide answers to some of these challenges. 34 refs., 11 figs., 5 tabs

Symmetry and bifurcations of momentum mappings

International Nuclear Information System (INIS)

Arms, J.M.; Marsden, J.E.; Moncrief, V.

1981-01-01

The zero set of a momentum mapping is shown to have a singularity at each point with symmetry. The zero set is diffeomorphic to the product of a manifold and the zero set of a homogeneous quadratic function. The proof uses the Kuranishi theory of deformations. Among the applications, it is shown that the set of all solutions of the Yang-Mills equations on a Lorentz manifold has a singularity at any solution with symmetry, in the sense of a pure gauge symmetry. Similarly, the set of solutions of Einstein's equations has a singularity at any solution that has spacelike Killing fields, provided the spacetime has a compact Cauchy surface. (orig.)

Quantum mechanics and hidden superconformal symmetry

Science.gov (United States)

Bonezzi, R.; Corradini, O.; Latini, E.; Waldron, A.

2017-12-01

Solvability of the ubiquitous quantum harmonic oscillator relies on a spectrum generating osp (1 |2 ) superconformal symmetry. We study the problem of constructing all quantum mechanical models with a hidden osp (1 |2 ) symmetry on a given space of states. This problem stems from interacting higher spin models coupled to gravity. In one dimension, we show that the solution to this problem is the Vasiliev-Plyushchay family of quantum mechanical models with hidden superconformal symmetry obtained by viewing the harmonic oscillator as a one dimensional Dirac system, so that Grassmann parity equals wave function parity. These models—both oscillator and particlelike—realize all possible unitary irreducible representations of osp (1 |2 ).

Symmetry and bifurcations of momentum mappings

Science.gov (United States)

Arms, Judith M.; Marsden, Jerrold E.; Moncrief, Vincent

1981-01-01

The zero set of a momentum mapping is shown to have a singularity at each point with symmetry. The zero set is diffeomorphic to the product of a manifold and the zero set of a homogeneous quadratic function. The proof uses the Kuranishi theory of deformations. Among the applications, it is shown that the set of all solutions of the Yang-Mills equations on a Lorentz manifold has a singularity at any solution with symmetry, in the sense of a pure gauge symmetry. Similarly, the set of solutions of Einstein's equations has a singularity at any solution that has spacelike Killing fields, provided the spacetime has a compact Cauchy surface.

Additional symmetries of supersymmetric KP hierarchies

International Nuclear Information System (INIS)

Stanciu, S.

1993-09-01

We investigate the additional symmetries of several supersymmetric KP hierarchies: The SKP hierarchy of Manin and Radul, the SKP 2 hierarchy, and the Jacobian SKP hierarchy. The main technical tool is the supersymmetric generalisation of a map originally due to Radul between the Lie algebra of superdifferential operators and the Lie algebra of vector fields on the space of supersymmetric Lax operators. In the case of the Manin-Radul SKP hierarchy we identify additional symmetries which form an algebra isomorphic to a subalgebra of superdifferential operators; whereas in the case of the Jacobian SKP, the (additional) symmetries are identified with the algebra itself. (orig.)

Patterns of symmetry breaking in chiral QCD

Science.gov (United States)

Bolognesi, Stefano; Konishi, Kenichi; Shifman, Mikhail

2018-05-01

We consider S U (N ) Yang-Mills theory with massless chiral fermions in a complex representation of the gauge group. The main emphasis is on the so-called hybrid ψ χ η model. The possible patterns of realization of the continuous chiral flavor symmetry are discussed. We argue that the chiral symmetry is broken in conjunction with a dynamical Higgsing of the gauge group (complete or partial) by bifermion condensates. As a result a color-flavor locked symmetry is preserved. The 't Hooft anomaly matching proceeds via saturation of triangles by massless composite fermions or, in a mixed mode, i.e. also by the "weakly" coupled fermions associated with dynamical Abelianization, supplemented by a number of Nambu-Goldstone mesons. Gauge-singlet condensates are of the multifermion type and, though it cannot be excluded, the chiral symmetry realization via such gauge invariant condensates is more contrived (requires a number of four-fermion condensates simultaneously and, even so, problems remain) and less plausible. We conclude that in the model at hand, chiral flavor symmetry implies dynamical Higgsing by bifermion condensates.

Symmetries of Taub-NUT dual metrics

International Nuclear Information System (INIS)

Baleanu, D.; Codoban, S.

1998-01-01

Recently geometric duality was analyzed for a metric which admits Killing tensors. An interesting example arises when the manifold has Killing-Yano tensors. The symmetries of the dual metrics in the case of Taub-NUT metric are investigated. Generic and non-generic symmetries of dual Taub-NUT metric are analyzed

Symmetry properties of fractional diffusion equations

Energy Technology Data Exchange (ETDEWEB)

Gazizov, R K; Kasatkin, A A; Lukashchuk, S Yu [Ufa State Aviation Technical University, Karl Marx strausse 12, Ufa (Russian Federation)], E-mail: gazizov@mail.rb.ru, E-mail: alexei_kasatkin@mail.ru, E-mail: lsu@mail.rb.ru

2009-10-15

In this paper, nonlinear anomalous diffusion equations with time fractional derivatives (Riemann-Liouville and Caputo) of the order of 0-2 are considered. Lie point symmetries of these equations are investigated and compared. Examples of using the obtained symmetries for constructing exact solutions of the equations under consideration are presented.

How does symmetry impact the flexibility of proteins?

Science.gov (United States)

Schulze, Bernd; Sljoka, Adnan; Whiteley, Walter

2014-02-13

It is well known that (i) the flexibility and rigidity of proteins are central to their function, (ii) a number of oligomers with several copies of individual protein chains assemble with symmetry in the native state and (iii) added symmetry sometimes leads to added flexibility in structures. We observe that the most common symmetry classes of protein oligomers are also the symmetry classes that lead to increased flexibility in certain three-dimensional structures-and investigate the possible significance of this coincidence. This builds on the well-developed theory of generic rigidity of body-bar frameworks, which permits an analysis of the rigidity and flexibility of molecular structures such as proteins via fast combinatorial algorithms. In particular, we outline some very simple counting rules and possible algorithmic extensions that allow us to predict continuous symmetry-preserving motions in body-bar frameworks that possess non-trivial point-group symmetry. For simplicity, we focus on dimers, which typically assemble with twofold rotational axes, and often have allosteric function that requires motions to link distant sites on the two protein chains.

Intrinsic Chevrolets at the SSC

International Nuclear Information System (INIS)

Brodsky, S.J.; Collins, J.C.; Ellis, S.D.; Gunion, J.F.; Mueller, A.H.

1984-01-01

The possibility of the production at high energy of heavy quarks, supersymmetric particles and other large mass colored systems via the intrinsic twist-six components in the proton wave function is discussed. While the existing data do not rule out the possible relevance of intrinsic charm production at present energies, the extrapolation of such intrinsic contributions to very high masses and energies suggests that they will not play an important role at the SSC

Dynamical symmetries of the shell model

International Nuclear Information System (INIS)

Van Isacker, P.

2000-01-01

The applications of spectrum generating algebras and of dynamical symmetries in the nuclear shell model are many and varied. They stretch back to Wigner's early work on the supermultiplet model and encompass important landmarks in our understanding of the structure of the atomic nucleus such as Racah's SU(2) pairing model and Elliot's SU(3) rotational model. One of the aims of this contribution has been to show the historical importance of the idea of dynamical symmetry in nuclear physics. Another has been to indicate that, in spite of being old, this idea continues to inspire developments that are at the forefront of today's research in nuclear physics. It has been argued in this contribution that the main driving features of nuclear structure can be represented algebraically but at the same time the limitations of the symmetry approach must be recognised. It should be clear that such approach can only account for gross properties and that any detailed description requires more involved numerical calculations of which we have seen many fine examples during this symposium. In this way symmetry techniques can be used as an appropriate starting point for detailed calculations. A noteworthy example of this approach is the pseudo-SU(3) model which starting from its initial symmetry Ansatz has grown into an adequate and powerful description of the nucleus in terms of a truncated shell model. (author)

Big break for charge symmetry

Energy Technology Data Exchange (ETDEWEB)

Miller, G.A. [Department of Physics, University of Washington, Seattle (United States); Kolck, U. van [Department of Physics, University of Arizona, Tucson (United States)

2003-06-01

Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of {sup i}sospin{sup ,} and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while the down quark has a negative charge of -1/3. If charge symmetry was exact, the proton and the neutron would have the same mass and they would both be electrically neutral. This is because the proton is made of two up quarks and a down quark, while the neutron comprises two downs and an up. Replacing up quarks with down quarks, and vice versa, therefore transforms a proton into a neutron. Charge-symmetry breaking causes the neutron to be about 0.1% heavier than the proton because the down quark is slightly heavier than the up quark. Physicists had already elucidated certain aspects of charge-symmetry breaking, but our spirits were raised greatly when we heard of the recent work of Allena Opper of Ohio University in the US and co-workers at the TRIUMF laboratory in British Columbia, Canada. Her team has been trying to observe a small charge-symmetry-breaking effect for several years, using neutron beams at the TRIUMF accelerator. The researchers studied the

On the symmetry of phosphorous doped ZnSe

Indian Academy of Sciences (India)

Unknown

Abstract. The site symmetry of P doped ZnSe is analysed in detail here, as the recent experiments suggest two possible symmetries Td and C3V. The reduction to C3V is attributed to the presence of natural impurity,. Ga. Our calculations based on molecular model and Green's functions suggest that the symmetry C3V is.

Inverse semigroups the theory of partial symmetries

CERN Document Server

Lawson, Mark V

1998-01-01

Symmetry is one of the most important organising principles in the natural sciences. The mathematical theory of symmetry has long been associated with group theory, but it is a basic premise of this book that there are aspects of symmetry which are more faithfully represented by a generalization of groups called inverse semigroups. The theory of inverse semigroups is described from its origins in the foundations of differential geometry through to its most recent applications in combinatorial group theory, and the theory tilings.

No-go for tree-level R-symmetry breaking

Energy Technology Data Exchange (ETDEWEB)

Liu, Feihu [University of Electronic Science and Technology of China, School of Physical Electronics, Chengdu (China); Liu, Muyang [Sichuan University, Center for Theoretical Physics, College of Physical Science and Technology, Chengdu (China); Sun, Zheng [Sichuan University, Center for Theoretical Physics, College of Physical Science and Technology, Chengdu (China); Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)

2017-11-15

We show that in gauge mediation models with tree-level R-symmetry breaking where supersymmetry and R-symmetries are broken by different fields, the gaugino mass either vanishes at one loop or finds a contribution from loop-level R-symmetry breaking. Thus tree-level R-symmetry breaking for phenomenology is either no-go or redundant in the simplest type of models. Including explicit messenger mass terms in the superpotential with a particular R-charge arrangement is helpful to bypass the no-go theorem, and the resulting gaugino mass is suppressed by the messenger mass scale. (orig.)

Mixed-symmetry superconductivity in two-dimensional Fermi liquids

International Nuclear Information System (INIS)

Musaelian, K.A.; Betouras, J.; Chubukov, A.V.; Joynt, R.

1996-01-01

We consider a two-dimensional (2D) isotropic Fermi liquid with attraction in both s and d channels and examine the possibility of a superconducting state with mixed s and d symmetry of the gap function. We show that both in the weak-coupling limit and at strong coupling, a mixed s+id symmetry state is realized in a certain range of interaction. Phase transitions between the mixed and the pure symmetry states are second order. We also show that there is no stable mixed s+d symmetry state at any coupling. copyright 1996 The American Physical Society

Global Anomaly Detection in Two-Dimensional Symmetry-Protected Topological Phases

Science.gov (United States)

Bultinck, Nick; Vanhove, Robijn; Haegeman, Jutho; Verstraete, Frank

2018-04-01

Edge theories of symmetry-protected topological phases are well known to possess global symmetry anomalies. In this Letter we focus on two-dimensional bosonic phases protected by an on-site symmetry and analyze the corresponding edge anomalies in more detail. Physical interpretations of the anomaly in terms of an obstruction to orbifolding and constructing symmetry-preserving boundaries are connected to the cohomology classification of symmetry-protected phases in two dimensions. Using the tensor network and matrix product state formalism we numerically illustrate our arguments and discuss computational detection schemes to identify symmetry-protected order in a ground state wave function.

Intrinsic flexibility of B-DNA: the experimental TRX scale.

Science.gov (United States)

Heddi, Brahim; Oguey, Christophe; Lavelle, Christophe; Foloppe, Nicolas; Hartmann, Brigitte

2010-01-01

B-DNA flexibility, crucial for DNA-protein recognition, is sequence dependent. Free DNA in solution would in principle be the best reference state to uncover the relation between base sequences and their intrinsic flexibility; however, this has long been hampered by a lack of suitable experimental data. We investigated this relationship by compiling and analyzing a large dataset of NMR (31)P chemical shifts in solution. These measurements reflect the BI BII equilibrium in DNA, intimately correlated to helicoidal descriptors of the curvature, winding and groove dimensions. Comparing the ten complementary DNA dinucleotide steps indicates that some steps are much more flexible than others. This malleability is primarily controlled at the dinucleotide level, modulated by the tetranucleotide environment. Our analyses provide an experimental scale called TRX that quantifies the intrinsic flexibility of the ten dinucleotide steps in terms of Twist, Roll, and X-disp (base pair displacement). Applying the TRX scale to DNA sequences optimized for nucleosome formation reveals a 10 base-pair periodic alternation of stiff and flexible regions. Thus, DNA flexibility captured by the TRX scale is relevant to nucleosome formation, suggesting that this scale may be of general interest to better understand protein-DNA recognition.

Positive Disintegration as a Process of Symmetry Breaking.

Science.gov (United States)

Laycraft, Krystyna

2017-04-01

This article presents an analysis of the positive disintegration as a process of symmetry breaking. Symmetry breaking plays a major role in self-organized patterns formation and correlates directly to increasing complexity and function specialization. According to Dabrowski, a creator of the Theory of Positive Disintegration, the change from lower to higher levels of human development requires a major restructuring of an individual's psychological makeup. Each level of human development is a relatively stable and coherent configuration of emotional-cognitive patterns called developmental dynamisms. Their main function is to restructure a mental structure by breaking the symmetry of a low level and bringing differentiation and then integration to higher levels. The positive disintegration is then the process of transitions from a lower level of high symmetry and low complexity to higher levels of low symmetry and high complexity of mental structure.

Intrinsic work function of molecular films

International Nuclear Information System (INIS)

Ivančo, Ján

2012-01-01

The electronic properties of molecular films are analysed with the consideration of the molecular orientation. The study demonstrates that surfaces of electroactive oligomeric molecular films can be classified—analogously to the elemental surfaces—by their intrinsic work functions. The intrinsic work function of molecular films is correlated with their ionisation energies; again, the behaviour is analogous to the correlation existing between the first ionisation energy of elements and the work function of the corresponding elemental surfaces. The proposed intrinsic work-function concept suggests that the mechanism for the energy-level alignment at the interfaces associated with molecular films is virtually controlled by work functions of materials brought into the contact. - Highlights: ► Molecular films exhibit their own (intrinsic) work function. ► Intrinsic work function is correlated with ionisation energy of molecular films. ► Intrinsic work function determines dipole at interface with a particular surface. ► Surface vacuum-level change upon film growth does not relate to interfacial dipole.

Quasigroup of local-symmetry transformations in constrained theories

International Nuclear Information System (INIS)

Chitaya, N.P.; Gogilidze, S.A.; Surovtsev, Yu.S.

1996-01-01

In the framework of the generalized Hamiltonian formalism by Dirac, the local symmetries of dynamical systems with first- and second-class constraints are investigated in the general case without restrictions on the algebra of constraints. The method of constructing the generator of local-symmetry transformations is obtained from the requirement for them to map the solutions of the Hamiltonian equations of motion into the solutions of the same equations. It is proved that second-class constraints do not contribute to the transformation law of the local symmetry entirely stipulated by all the first-class constraints (only by them) of an equivalent set passing to which from the initial constraint set is always possible and is presented. A mechanism of occurrence of higher derivatives of coordinates and group parameters in the symmetry transformation law in the Noether second theorem is elucidated. In the latter case it is shown that the obtained transformations of symmetry are canonical in the extended (by Ostrogradsky) phase space. It is thereby shown in the general case that the degeneracy of theories with the first- and second-class constraints is due to their invariance under local-symmetry transformations. It is also shown in the general case that the action functional and the corresponding Hamiltonian equations of motion are invariant under the same quasigroup of local-symmetry transformations. 29 refs

Evidence for SU(3) symmetry breaking from hyperon production

International Nuclear Information System (INIS)

Yang Jianjun

2002-01-01

We examine the SU(3) symmetry breaking in hyperon semileptonic decays (HSD) by considering two typical sets of quark contributions to the spin content of the octet baryons: set 1 with SU(3) flavor symmetry and set 2 with SU(3) flavor symmetry breaking in the HSD. The quark distributions of the octet baryons are calculated with a successful statistical model. Using an approximate relation between the quark fragmentation functions and the quark distributions, we predict the polarizations of the octet baryons produced in e + e - annihilation and semi-inclusive deep lepton-nucleon scattering in order to reveal the SU(3) symmetry breaking effect on the spin structure of the octet baryons. We find that the SU(3) symmetry breaking significantly affects the hyperon polarization. The available experimental data on the Λ polarization seem to favor the theoretical predictions with SU(3) symmetry breaking. We conclude that there is a possibility to get collateral evidence for SU(3) symmetry breaking from hyperon production. The theoretical errors for our predictions are discussed

Discrete R symmetries for the MSSM and its singlet extensions

CERN Document Server

Lee, Hyun Min; Ratz, Michael; Ross, Graham G; Schieren, Roland; Schmidt-Hoberg, Kai; Vaudrevange, Patrick K S

2011-01-01

We determine the anomaly free discrete R symmetries, consistent with the MSSM, that commute with SU(5) and suppress the $\\mu$ parameter and nucleon decay. We show that the order M of such $Z_M^R$ symmetries has to divide 24 and identify 5 viable symmetries. The simplest possibility is a $Z_4^R$ symmetry which commutes with SO(10). We present a string-derived model with this $Z_4^R$ symmetry and the exact MSSM spectrum below the GUT scale; in this model $Z_4^R$ originates from the Lorentz symmetry of compactified dimensions. We extend the discussion to include the singlet extensions of the MSSM and find $Z_4^R$ and $Z_8^R$ are the only possible symmetries capable of solving the $\\mu$ problem in the NMSSM. We also show that a singlet extension of the MSSM based on a $Z_{24}^R$ symmetry can provide a simultaneous solution to the $\\mu$ and strong CP problem with the axion coupling in the favoured window.

Symmetry Energy as a Function of Density and Mass

International Nuclear Information System (INIS)

Danielewicz, Pawel; Lee, Jenny

2007-01-01

Energy in nuclear matter is, in practice, completely characterized at different densities and asymmetries, when the density dependencies of symmetry energy and of energy of symmetric matter are specified. The density dependence of the symmetry energy at subnormal densities produces mass dependence of nuclear symmetry coefficient and, thus, can be constrained by that latter dependence. We deduce values of the mass dependent symmetry coefficients, by using excitation energies to isobaric analog states. The coefficient systematic, for intermediate and high masses, is well described in terms of the symmetry coefficient values of a a V = (31.5-33.5) MeV for the volume coefficient and a a S = (9-12) MeV for the surface coefficient. These two further correspond to the parameter values describing density dependence of symmetry energy, of L∼95 MeV and K sym ∼25 MeV

Pauli-Guersey symmetry in gauge theories

International Nuclear Information System (INIS)

Stern, J.

1983-05-01

Gauge theories with massless or massive fermions in a selfcontragredient representation exhibit global symmetries of Pauli-Guersey type. Some of them are broken spontaneously leading to a difermion Goldstone bosons. An example of a boson version of the Pauli-Guersey symmetry is provided by the Weinberg-Salam model in the limit THETAsub(w)→O

Total internal reflection second-harmonic generation: probing the alkane water interface

International Nuclear Information System (INIS)

Conboy, J.C.; Daschbach, J.L.; Richmond, G.L.