Limits Of Symmetry Research Articles

Interocular Symmetry and Repeatability of Central Corneal Thickness and Corneal Endothelial Cell Morphology and Density in Healthy Eyes of Congolese

ABSTRACT Purpose To determine the limits of normal interocular symmetry and the repeatability of central corneal thickness (CCT) and endothelial cell morphology and density. Methods Two hundred and seventy-eight subjects (age: 10.9–80.7 years) with healthy eyes were studied. CCT as well as endothelial cell morphology and density were measured by non-contact specular microscopy. Three measurements were obtained per eye per participant. Upper and lower tolerance limits of normal interocular symmetry were defined as the 2.5th and 97.5th percentiles of the interocular differences in CCT, endothelial cell density (CECD), coefficient of variation (CoV), hexagonality, and cell size. Repeatability was determined using the intraclass coefficient correlation (ICC), the coefficient of variation (CV), and the test–retest variability standard deviation (TRTSD). Results The mean interocular differences were −1.05 ± 17.5 µm (p = .32) for CCT and 0.5 ± 90.8 cells/mm2 (p = .76) for CECD. The 2.5th and 97.5th percentiles of the interocular differences were −13.9 and 15.4 µm for CCT and −177.4 cells/mm2 to 182.0 cells/mm2 for CECD. Only interocular difference in CoV correlated weakly with age (r = −0.22, P < .001). ICCs were 0.93 (95% CI: 0.89–0.96, P < .001) for CCT and 0.95 (0.94–0.96, P < .001) for CECD. CV and TRTSD were 1.2% ± 5.3% and 4.4 ± 3.4 µm for CCT and 2.4% ± 3.9% and 17.7 ± 7.7 cells/mm2 for CECD, respectively. Conclusions CCT and CECD showed good repeatability and interocular symmetry in normal Congolese subjects. Absolute interocular differences in CCT and CECD exceeding 15.5 µm and 182 cells/mm2, respectively, should be considered suspicious and investigated. When comparing two intrasession measurements from the same eye, a difference of approximately 4.5 µm in CCT and 18 cells/mm2 or greater may be considered statistically significant.

Anterior shin muscles CMAP measurements: Normal limits of symmetry and intra- and interobserver reliability

ObjectiveThe normal limits of symmetry for the compound muscle action potential of the shin muscles (CMAPshin) have not been determined yet. The goal of this study is to provide extensive data on the limits of symmetry and the reliability of CMAPshin. MethodsThe study was conducted in normal healthy males and females. All subjects underwent CMAPshin measurements bilaterally. The median percent differences of right/left amplitude/area, with range of these measurements, were calculated. In addition, the intra- and interobserver reliability was examined in a separate population. ResultsThe study group consisted of 58 healthy individuals. The median percent right/left difference for amplitude and area were respectively 7.2% (range 0–23.6%) and 5.4% (range 0.7–25.6%). Right/left difference of the amplitude/area of the CMAPshin greater than 24%/26% respectively can be considered as pathological. The Pearson correlation coefficients (r) for the intra-observer reliability amplitude/area are 0.905/0.882 and for the inter-observer reliability are 0.968/0.981. ConclusionsThe results confirm symmetry and good intra- and interobserver reliability in CMAPshin measurements. SignificanceCMAPshin can be used in practice to estimate axonal loss in case of a foot drop. Data studies examining symmetry of CMAPshin can facilitate in the clinical interpretation of these nerve conduction studies.

Baropodometric technology used to analyze types of weight-bearing during hemiparetic upright position

INTRODUCTION: Although baropodometric analysis has been published since the 1990s, only now it is found a considerable number of studies showing different uses in the rehabilitation. OBJECTIVE: To amplify the use of this technology, this research aimed to analyze baropodometric records during upright position of subjects with hemiparesis, describing a way to define weight-bearing profiles in this population. METHOD: 20 healthy subjects were matched by gender and age with 12 subjects with chronic spastic hemiparesis. This control group was formed to establish the limits of symmetry during weight-bearing distribution in the hemiparesis group. Next, hemiparesis group was submitted to procedures to measure baropodometric records used to provide variables related to the weight-bearing distribution, the arch index and the displacements in the center of pressure (CoP). Data were used to compare differences among kinds of weight-bearing distribution (symmetric, asymmetric toward non-paretic or paretic foot) and coordination system for CoP displacements. RESULTS: Hemiparesis group was compounded by eight symmetrics, eight asymmetrics toward non-paretic foot and four asymmetric toward paretic foot. Significant differences in the weight-bearing distributions between non-predominantly and predominantly used foot did not promote differences in the other baropodometric records (peak and mean of pressure, and support area). Mainly in the asymmetry toward non-paretic foot it was observed significant modifications of the baropodometric records. CONCLUSION: Baropodometric technology can be used to analyze weight-bearing distribution during upright position of subjects with hemiparesis, detecting different kinds of weight-bearing profiles useful to therapeutic programs and researches involving subjects with this disability.

Limits of normality and symmetry in standing back shape and posture

female ones as expected. However no significant differences were found between key distances on the left and right sides of the back. In females, the only significant differences between the left and right sides of the back were found in the distance between the acromium and the inferior scapula. The right side was significantly smaller than the left side. Further the distance between the inferior angle of the scapula and the apical thoracic vertebra on the right side was significantly longer than the left side. The left shoulder in females was also significantly higher then the right shoulder. No statistically significant differences at the inferior angle of scapula, iliac crests or PSIS were found in females. Discussion The results of this study suggest that young asymptomatic subjects are very symmetrical with males being more symmetrical than females. In females asymmetries exist predominantly around the shoulder. Conclusions Ranges for normality of back shape and posture suggest that overall young asymptomatic males and females are very symmetrical, with the exception of shoulder values in young females. The normative ranges provided should help clinicians decide when postural retraining exercises/ conservative treatment is warranted as well as aid the documentation of treatment effectiveness.

Erratum: Limits of custodial symmetry [Phys. Rev. D80, 095001 (2009)

We introduce a toy model implementing the proposal of using a custodial symmetry to protect the Zbb coupling from large corrections. This "doublet-extended standard model" adds a weak doublet of fermions (including a heavy partner of the top quark) to the particle content of the standard model in order to implement an O(4) x U(1)_X = SU(2)_L x SU(2)_R x P_{LR} x U(1)_X symmetry that protects the Zbb coupling. This symmetry is softly broken to the gauged SU(2)_L x U(1)_Y electroweak symmetry by a Dirac mass M for the new doublet; adjusting the value of M allows us to explore the range of possibilities between the O(4)-symmetric (M to 0) and standard-model-like (M to infinity) limits. In this simple model, we find that the experimental limits on the Zbb coupling favor smaller M while the presence of a potentially sizable negative contribution to T strongly favors large M. A fit to all precision electroweak data shows that the heavy partner of the top quark must be heavier than about 3.4 TeV, making it difficult to search for at LHC. This result demonstrates that electroweak data strongly limits the amount by which the custodial symmetry of the top-quark mass generating sector can be enhanced relative to the standard model. Using an effective field theory calculation, we illustrate how the leading contributions to alpha T, alpha S and the Zbb coupling in this model arise from an effective operator coupling right-handed top-quarks to the Z-boson, and how the effects on these observables are correlated. We contrast this toy model with extra-dimensional models in which the extended custodial symmetry is invoked to control the size of additional contributions to alpha T and the Zbb coupling, while leaving the standard model contributions essentially unchanged.

Approximate analytical solutions of the Klein–Gordon equation with the Pöschl–Teller potential including the centrifugal term

By employing a new improved approximation scheme to deal with the centrifugal term, we solve approximately the Klein–Gordon equation with scalar and vector Pöschl–Teller potentials for the arbitrary orbital angular momentum number l. The bound state energy equation and the unnormalized radial wave functions have been approximately obtained by using the basic concept of the supersymmetric shape invariance formalism and the function analysis method. We also discuss in detail the identity of the energy spectra for the Pöschl–Teller potential in the Klein–Gordon equation and the Dirac equation under the limits of the spin symmetry and pseudospin spin symmetry.

Activism and the Limits of Symmetry: The Public Relations Battle Between Colorado GASP and Philip Morris

Litigation has forced tobacco companies like Philip Morris to disclose more than 7 million internal documents, including previously confidential public relations plans. We draw from this archive, as well as from activist materials, to demonstrate that, despite vigorous industry efforts to thwart them, activists in this case employed strategies of values advocacy and inoculation and capitalized on economic benefits to persuade publics. This watershed case poses continued challenges for the 2-way symmetrical or mixed-motive theoretical model of public relations. Accounting for public relations activism and understanding its voice in influencing contemporary public debate requires that scholars move beyond this widely accepted model that stresses compromise between activists and organizations. An alternative rhetorical theory of activist public relations is posited to account for groups that refuse to accommodate opponents.

Limits of custodial symmetry

We introduce a toy model implementing the proposal of using a custodial symmetry to protect the $Z{b}_{L}{\overline{b}}_{L}$ coupling from large corrections. This ``doublet-extended standard model'' adds a weak doublet of fermions (including a heavy partner of the top quark) to the particle content of the standard model in order to implement an $O(4)\ifmmode\times\else\texttimes\fi{}U(1{)}_{X}\ensuremath{\sim}SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}SU(2{)}_{R}\ifmmode\times\else\texttimes\fi{}{P}_{LR}\ifmmode\times\else\texttimes\fi{}U(1{)}_{X}$ symmetry in the top-quark mass generating sector. This symmetry is softly broken to the gauged $SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{Y}$ electroweak symmetry by a Dirac mass $M$ for the new doublet; adjusting the value of $M$ allows us to explore the range of possibilities between the $O(4)$-symmetric ($M\ensuremath{\rightarrow}0$) and standard-model-like ($M\ensuremath{\rightarrow}\ensuremath{\infty}$) limits. In this simple model, we find that the experimental limits on the $Z{b}_{L}{\overline{b}}_{L}$ coupling favor smaller $M$ while the presence of a potentially sizable negative contribution to $\ensuremath{\alpha}T$ strongly favors large $M$. Comparison with precision electroweak data shows that the heavy partner of the top quark must be heavier than about 3.4 TeV, making it difficult to search for at LHC. This result demonstrates that electroweak data strongly limit the amount by which the custodial symmetry of the top-quark mass generating sector can be enhanced relative to the standard model. Using an effective field theory calculation, we illustrate how the leading contributions to $\ensuremath{\alpha}T$, $\ensuremath{\alpha}S$, and the $Z{b}_{L}{\overline{b}}_{L}$ coupling in this model arise from an effective operator coupling right-handed top quarks to the $Z$ boson, and how the effects on these observables are correlated. We contrast this toy model with extradimensional models in which the extended custodial symmetry is invoked to control the size of additional contributions to $\ensuremath{\alpha}T$ and the $Z{b}_{L}{\overline{b}}_{L}$ coupling, while leaving the standard model contributions essentially unchanged.

Les limites de la symétrie

Ce texte se propose d’introduire le debat a propos de l’ouvrage de Bruno Latour Changer de societe. Refaire de la Sociologie, publie aux Editions La Decouverte en 2006. Faut-il suivre Latour dans sa tentative de reinventer la sociologie dans son ensemble ? Les qualites d’ecriture de cet ouvrage lui permettent de faire exister une sorte de fiction theorique dont il faut souligner la fecondite, mais dont les limites apparaissent tres vite lorsque des auteurs moins talentueux essaient de s’en inspirer. Neanmoins, ses idees peuvent stimuler l’ensemble de la sociologie, alors que le projet de la reconstruire en mettant au rebus la plus grande partie, qu’il defend dans ce livre, parait voue a l’echec.

Usages et limites de la symétrie dans les représentations graphiques en géographie

La symetrie est basee sur l’idee platonicienne d’harmonie. Comprise comme un element d’une plus grande complexite, c’est aujourd’hui un principe scientifique fondamental qui interpelle notre discipline et l’invite a reformuler un ancrage theorique. L’espace geographique ne peut etre par definition un espace asymetrique (sans symetrie), car il ne possederait aucune manifestation traduisant son organisation (espace homogene et isotrope). En quoi intervient alors la symetrie ? Les translations (mais aussi les rotations et surtout les dispositifs en miroir) sont souvent considerees, en geographie, comme correspondant seules au concept de symetrie alors que celle-ci apparait aussi fondamentalement dans les manifestations fractales tangibles (formes) ou structurelles (lois). Associe a des formes euclidiennes, cet aspect tres partiel de la symetrie constitue un element essentiel de la pratique chorematique. Nous craignons qu’une telle approche (associant perception et representation) fasse obstacle (obstruction) a une theorisation formelle de l’espace geographique qui l’instrumentaliserait.

On the modified Green operator integral for polygonal, polyhedral and other non-ellipsoidal inclusions

Abstract A “strange” particularity of polyhedral inclusions and of fibres of regular polygonal cross sections has been recently stressed in the literature. For respectively fully or transversally isotropic elasticity of the embedding material, they have a mean and a central Green operator integral both equal to the uniform one of respectively the sphere or the cylindrical fibre. In using the Radon transform (RT) method, this particularity is here shown to be shared by much larger shape types in the same limits of material elasticity symmetry. As a subcase, even more shape types fulfill the similar particularity for material linear properties of second-rank characteristic tensor, such as thermal conductivity, magnetic or dielectric properties. When calculated using the RT method, the modified Green operator integral at any interior point of a bounded domain (inclusion) takes the form of a weighted average over an angular distribution of a single elementary operator. The weight function is geometrically defined from the characteristic function of the domain, and the four-rank or second-rank elementary operator depends on the material linear property of concern. The RT method simply shows that the noticed particularity is due to matching symmetry between the inclusion shape (through the weight function) and the material property (through the elementary operator). The general geometrical characteristics of the inclusion shapes belonging to these sphere-class and cylindrical-fibre-class are specified, and some remarkable shapes of these classes are commented.

Symétrie et reproductibilité temporelle des données neurographiques

The aims of the present study are to document side-to-side differences and temporal variability, between two trials (T1 and T2 at a time interval of 3 months) of nerve conduction measurements collected from 30 healthy subjects (mean age 22 ± 2 years). Methods. – The protocol at T1 consisted of motor nerve conduction studies of median, ulnar, peroneal and tibial nerves bilaterally, with measurement of (a) motor response size (amplitude and area); (b) terminal latency; (c) minimal, mean and maximal F–wave latency; (d) motor conduction velocity; and (e) F–wave occurrence. T1 also involved sensory nerve conduction studies of median, ulnar, radial, lateral and medial cutaneous, sural and superficial peroneal nerves bilaterally, with measurement of sensory potential size (amplitude and area) and computation of sensory conduction velocity. The protocol at T2 consisted of identical measurements from the dominant side. Results and conclusion. – There was a negative relationship between the variability of parameters evaluating nervous conduction and the length of the nerve segment under study. Thus, the smallest side-to-side and temporal variabilities are measured for minimal F-wave latencies (on average 2–3%). The limits of symmetry and temporal variability are particularly useful for diagnosis of unilateral peripheral neuropathy or neurophysiological follow-up of patients with neuropathy, when the variability of the parameter under study is weak and when there is a high correlation between values recorded on the left and on the right or at T1 and T2. This was the case for motor response size of tibial and ulnar nerves, sensory potential size of radial nerve and minimal F-wave latencies from each studied motor nerve.

Motility modes of Spiroplasma melliferum BC3: a helical, wall-less bacterium driven by a linear motor.

Spiroplasma are members of the Mollicutes (Mycoplasma, Acholeplasma and Spiroplasma) - the simplest, minimal, free-living and self-replicating forms of life. The mollicutes are unique among bacteria in completely lacking cell walls and flagella and in having an internal, contractile cytoskeleton, which also functions as a linear motor. Spiroplasma are helical, chemotactic and viscotactic active swimmers. The Spiroplasmal cytoskeleton is a flat ribbon composed of seven pairs of fibrils. The ribbon is attached to the inner side of the cell membrane along its innermost (shortest) helical line. The cell's geometry and dynamic helical parameters, and consequently motility, can be controlled by changing differentially and in a co-ordinated manner, the length of the fibrils. We identified several consistent modes of cell movements and motility originating, most likely, as a result of co-operative or local molecular switching of fibrils: (i). regular extension and contraction within the limits of helical symmetry (this mode also includes straightening, beyond what is allowed by helical symmetry, and reversible change of helical sense); (ii). spontaneous and random change of helical sense originating at random sites along the cell (these changes propagate along the cell in either direction and hand switching is completed within approximately 0.08 second); (iii). forming a deformation on one of the helical turns and propagating it along the cell (these helical deformations may travel along the cell at a speed of up to approximately 40 microm s-1); (iv). random bending, flexing and twitching (equivalent to tumbling). In standard medium (viscosity = 1.147 centipoise) the cells run at approximately 1.5 microm s-1, have a Reynolds number of approximately 3.5 x 10-6 and consume approximately 30 ATP molecules s-1. Running velocity, duration, persistence and efficiency increase with viscosity upon adding ficoll, dextran and methylcellulose to standard media. Relative force measurements using optical tweezers confirm these findings.

The Limits of Symmetry: A Game Theory Approach to Symmetric and Asymmetric Public Relations

(1991). The Limits of Symmetry: A Game Theory Approach to Symmetric and Asymmetric Public Relations. Public Relations Research Annual: Vol. 3, No. 1-4, pp. 115-131.

Technicolor

The need for reexamination of the standard model of strong, weak, and electromagnetic interactions is discussed, especially with regard to 't Hooft's criterion of naturalness. It has been argued that theories with fundamental scalar fields tend to be unnatural at relatively low energies. There are two solutions to this problem: (i) a global supersymmetry, which ensures the absence of all the naturalness-violating effects associated with scalar fields, and (ii) composite structure of the scalar fields, which starts showing up at energy scales where unnatural effects would otherwise have appeared. With reference to the second solution, this article reviews the case for dynamical breaking of the gauge symmetry and the technicolor scheme for the composite Higgs boson. This new interaction, of the scaled-up quantum chromodynamic type, keeps the new set of fermions, the technifermions, together in the Higgs particles. It also provides masses for the electroweak gauge bosons ${W}^{\ifmmode\pm\else\textpm\fi{}}$ and ${Z}^{0}$ through technifermion condensate formation. In order to give masses to the ordinary fermions, a new interaction, the extended technicolor interaction, which would connect the ordinary fermions to the technifermions, is required. The extended technicolor group breaks down spontaneously to the technicolor group, possibly as a result of the "tumbling" mechanism, which is discussed here. In addition, the author presents schemes for the isospin breaking of mass matrices of ordinary quarks in the technicolor models. In generalized technicolor models with more than one doublet of technifermions or with more than one technicolor sector, we have additional low-lying degrees of freedom, the pseudo-Goldstone bosons. The pseudo-Goldstone bosons in the technicolor model of Dimopoulos are reviewed and their masses computed. In this context the vacuum alignment problem is also discussed. An effective Lagrangian is derived describing colorless low-lying degrees of freedom for models with two technicolor sectors in the combined limits of chiral symmetry and large number of colors and technicolors. Finally, the author discusses suppression of flavor-changing neutral currents in the extended technicolor models.