Impact Of Symmetry Research Articles

Inefficiency of pure Nash equilibria in network congestion games: the impact of symmetry and network structure

Inefficiency of pure Nash equilibria in network congestion games: the impact of symmetry and network structure

Carbon burning at stellar energies

Fusion reactions with light nuclei play an essential role in understanding the energy production, the nucleosynthesis of chemical elements and the evolution of massive stars. The measurement of key fusion reactions at stellar energies is thus of interest, but highly challenging since the associated cross sections are extremely small, of the sub-nanobarn range. Among these reactions, the fusion of carbon nuclei, which drives the stellar carbon burning phase, is deeply connected with essential microscopic features such as the impact of symmetries, the access to quantum states, emerging of resonances or Pauli repulsion effects. These may manifest themselves in exceptional behaviour of the S-factor of this particular system and the precision of extrapolations to deep sub-barrier energies is limited. The present contribution discusses recent experimental results of the nuclear astrophysics community on the measurement of the carbon + carbon fusion reaction down to the astrophysics region. The interplay between nuclear structure, nucleosynthesis and stellar evolution is addressed.

Measuring Electron Correlation: The Impact of Symmetry and Orbital Transformations.

In this perspective, the various measures of electron correlation used in wave function theory, density functional theory and quantum information theory are briefly reviewed. We then focus on a more traditional metric based on dominant weights in the full configuration solution and discuss its behavior with respect to the choice of the N-electron and the one-electron basis. The impact of symmetry is discussed, and we emphasize that the distinction among determinants, configuration state functions and configurations as reference functions is useful because the latter incorporate spin-coupling into the reference and should thus reduce the complexity of the wave function expansion. The corresponding notions of single determinant, single spin-coupling and single configuration wave functions are discussed and the effect of orbital rotations on the multireference character is reviewed by analyzing a simple model system. In molecular systems, the extent of correlation effects should be limited by finite system size and in most cases the appropriate choices of one-electron and N-electron bases should be able to incorporate these into a low-complexity reference function, often a single configurational one.

Numerical Investigation of the Effect of Symmetry on Evaporation Triggered Elastocapillary Top-Gathering of High Aspect Ratio Micropillars

High-aspect-ratio (HAR) micropillar arrays offer a wide range of applications in micro-contact printing, switchable transparent optical windows, superhydrophobic surfaces, mechanical sensors, and actuators, due to their properties such as large surface area and excellent mechanical compliance. However, owing to their high aspect ratio, these microstructures are prone to lateral deflection by elastocapillary forces in liquid environments, which is known as top-gathering, limiting their manufacturing processes and applications. Here, the impact of symmetry on evaporation triggered top-gathering of micropillars was studied numerically. The initiation of the micropillar deflection due to capillary forces under varying force distributions was simulated using a COMSOL Multiphysics simulation package. The simulation was carried out for the configurations of two, four, and an array of micropillars. For the four micropillar configuration, a new equation was suggested for calculating the micropillar deflection due to elastocapillary forces, using force distributions around the micropillars. The suggested equation was verified by comparison with the experimental observations. The effect of droplet evaporation on deflection/top-gathering of micropillars was also investigated. It was found that initiation of deflection is due to asymmetry at the rim of the droplet, generating domino-like deflection of the other micropillars. This study provides a new equation/criterion for estimating deflection of the micropillars, suggesting array designs that are resistant to such deflections when interacting with liquids.

Impact of symmetry on ergodic properties of triangular billiards.

Polygonal billiards constitute some of the simplest yet counterintuitive dynamical systems in physics. Even basic features of the dynamics, such as ergodicity of the microcanonical distribution or the decay of correlations have not been settled in general. In this Letter, we will highlight the importance of symmetries of the billiard table for the resulting dynamics. Although typical triangular billiards appear to show correlation decay, symmetric billiards may not even be ergodic with respect to the uniform distribution in phase space.

Current Applications of Gas Sensor Based on 2-D Nanomaterial: A Mini Review.

Gas sensor, as one of the most important devices to detect noxious gases, provides a vital way to monitor the concentration and environmental information of gas in order to guarantee the safety of production. Therefore, researches on high sensitivity, high selectivity, and high stability have become hot issues. Since the discovery of the nanomaterial, it has been increasingly applied to the gas sensor for its distinguishing surface performances. However, 0-D and 1-D nanomaterials, with limited electronic confinement effect and surface effect, cannot reach the requirement for the production of gas sensors. This paper gives an introduction about the current researching progress and development trend of 2-D nanomaterials, analyzes the common forms of 2-D nanoscale structure, and summarizes the mechanism of gas sensing. Then, widely concerned factors including morphological properties and crystalline structure of 2-D nanomaterial, impact of doped metal on the sensibility of gas sensors, impact of symmetry, and working temperature on the selectivity of gas sensors have been demonstrated in detail. In all, the detailed analysis above has pointed out a way for the development of new 2-D nanomaterial and enhancing the sensibility of gas sensors.

Universal behavior of the apparent fragility in ultraslow glass forming systems

Despite decades of studies on the grand problem of the glass transition the question of well-defined universal patterns, including the key problem of the previtreous behavior of the primary (structural) relaxation time, remains elusive. This report shows the universal previtreous behavior of the apparent fragility, i.e. the steepness index mP (T > Tg) = d log10τ(T)/d( Tg/T). It is evidenced that mP(T) = 1(T − T*), for T → Tg and T*= Tg − Δ T*. Basing on this finding, the new 3-parameter dependence for portraying the previtreous behavior of the primary relaxation time has been derived: τ(T) = CΩ((T − T*)/T)−Ω × [exp((T − T*)/T)]Ω. The universality of obtained relations is evidenced for glass formers belonging to low molecular weight liquids, polymers (melt and solid), plastic crystals, liquid crystals, resins and relaxors. They exhibit clear preferences either for the VFT or for the critical-like descriptions, if recalled already used modeling. The novel relation can obey even above the dynamic crossover temperature, with the power exponent Ω ranging between ~17 (liquid crystals) to ~57 (glycerol), what may indicate the impact of symmetry on the previtreous effect. Finally, the emerging similarity to the behavior in the isotropic phase of nematic liquid crystals is recalled.

Rigorous use of symmetry within the construction of multidimensional potential energy surfaces.

A method is presented, which allows for the rigorous use of symmetry within the construction of multidimensional potential energy surfaces (PESs). This approach is based on a crude but very fast energy estimate, which retains the symmetry of a molecule. This enables the efficient use of coordinate systems, which mix molecular and permutational symmetry, as, for example, in the case of normal coordinates with subsets of localized normal coordinates. The impact of symmetry within the individual terms of an expansion of the PES is studied together with a symmetry consideration within the individual electronic structure calculations. A trade between symmetry within the surface and the electronic structure calculations has been observed and has been investigated in dependence on different coordinate systems. Differences occur between molecules belonging to Abelian point groups in contrast to non-Abelian groups, in which further benefits can be achieved by rotating normal coordinates belonging to degenerate vibrational frequencies. In general, the exploitation of surface symmetry was found to be very important within the construction of PESs of small and medium-sized molecules-irrespective of the coordinate system. Benchmark calculations are provided for formaldehyde, ethene, chloromethane, and cubane.

The Impact of Symmetry: Explaining Contradictory Results Concerning Working Memory, Reasoning, and Complex Problem Solving.

Findings of studies on the unique effects of reasoning and working memory regarding complex problem solving are inconsistent. To find out if these inconsistencies are due to a lack of symmetry between the studies, we reconsidered the findings of three published studies on this issue, which resulted in conflicting conclusions regarding the inter-relations between reasoning, working memory, and complex problem solving. This was achieved by analysing so far unpublished problem solving data from the study of Bühner, Krumm, Ziegler, and Plücken (2006) (N= 124). One of the three published studies indicated unique effects of working memory and reasoning on complex problem solving using aggregated scores, a second study found no unique contribution of working memory using only figural scores, and a third study reported a unique influence only for reasoning using only numerical scores. Our data featured an evaluation of differences across content facets and levels of aggregation of the working memory scores. Path models showed that the results of the first study could not be replicated using content aggregated scores; the results of the second study could be replicated if only figural scores were used, and the results of the third study could be obtained by using only numerical scores. For verbal content, none of the published results could be replicated. This leads to the assumption that not only symmetry is an issue when correlating non-symmetrical data, but that content also has to be taken into account when comparing different studies on the same topic.

On the best constants in Sobolev inequalities on the solid torus in the limit casep= 1

AbstractIn this paper, we analyze the problem of determining the best constants for the Sobolev inequalities in the limiting case wherep=1${p=1}$. Firstly, the special case of the solid torus is studied, whenever it is proved that the solid torus is an extremal domain with respect to the second best constant and totally optimal with respect to the best constants in the trace Sobolev inequality. Secondly, in the spirit of Andreu, Mazon and Rossi [3], a Neumann problem involving the 1-Laplace operator in the solid torus is solved. Finally, the existence of both best constants in the case of a manifold with boundary is studied, when they exist. Further examples are provided where they do not exist. The impact of symmetries which appear in the manifold is also discussed.

Impact of symmetry on the ferroelectric properties of CaTiO3 thin films

Epitaxial strain is a powerful tool to induce functional properties such as ferroelectricity in thin films of materials that do not possess ferroelectricity in bulk form. In this work, a ferroelectric state was stabilized in thin films of the incipient ferroelectric, CaTiO3, through the careful control of the biaxial strain state and TiO6 octahedral rotations. Detailed structural characterization was carried out by synchrotron x-ray diffraction and scanning transmission electron microscopy. CaTiO3 films grown on La0.18Sr0.82Al0.59Ta0.41O3 (LSAT) and NdGaO3 (NGO) substrates experienced a 1.1% biaxial strain state but differed in their octahedral tilt structures. A suppression of the out-of-plane rotations of the TiO6 octahedral in films grown on LSAT substrates resulted in a robust ferroelectric I4 mm phase with remnant polarization ∼5 μC/cm2 at 10 K and Tc near 140 K. In contrast, films grown on NGO substrates with significant octahedral tilting showed reduced polarization and Tc. These results highlight the key role played by symmetry in controlling the ferroelectric properties of perovskite oxide thin films.

Impact of symmetry in transport properties of graphene nanoribbons with defects

We report a theoretical investigation of the impact of asymmetry in the geometry of graphene nanoribbons (GNR) on the current-voltage characteristics caused by introducing the structural defects using ab initio methods. Only the most possible structural defects were considered: mono vacancy, Stone-Wales (SW) defect with different orientation, and partial hydrogen passivation on the GNR surface. It is found that in case of SW defects the value of current is four times higher at the negative voltage than in case of structures with mono vacancy defect. Also, the impact of orientation of the SW defect on the I-V characteristics was studied.

Quantifying and Assessing the Effect of Chemical Symmetry in Metabolic Pathways

Atom tracing provides valuable information in many analyses of metabolic networks including pathway inference and flux estimation. Symmetries-mapping operations that produce atom equivalencies-introduce alternative tracings when multiple atom mappings are aggregated. Although several attempts have been made to consider symmetry while curating atom mappings, a definition of the symmetry amenable to automated computation and a systematic quantification of the extent of symmetries in both compounds and reactions is still lacking. Moreover, the impact of symmetries on the calculation of the atom economy of pathways and the simulation of isotopomer distribution is yet to be assessed. In this study, we formulate the symmetries of both compounds and reactions as automorphic mappings of the corresponding graph representations. We investigate the extent of both compound and reaction symmetries in several metabolic systems. We find, through random walking in the metabolic network of E.coli , that alternative tracings originated from symmetries could give rise to considerable amount of differential conservation of atoms and distinct transition patterns of the isotopomer distribution.

Rational Irrationality and Group Size: The Effect of Biased Beliefs on Individual Contributions Towards Collective Goods

The price of irrationality or belief manipulation varies as we move from small to large group settings. Individual members of large groups can more cheaply bias downwards their beliefs as to the immorality of their free-riding thereby circumventing internal moral constraints. The relative anonymity inherent to large number settings moreover reduces social pressures against free-riding stemming from some common ethical or moral norms. Both selfish individuals facing an internal moral constraint to behave altruistically and those with altruistic preferences have an incentive to bias upward their belief of the decisiveness of their contribution in large number settings. In addition, the impact of symmetry and the illusion of control can introduce biases regarding the expected reactions of others to one's own decisions. The loosening of moral constraints will tend to increase free-rider behavior while biased beliefs about the decisiveness of one's contribution or the reaction of others to one's actions will tend to decrease such behavior.

Patient preference for and reports of provider behavior: Impact of symmetry on patient outcomes.

Research has suggested that congruence between patient characteristics and contextual characteristics is a more robust predictor of outcomes than either patient or context characteristics alone. The goal of the present study was to examine the degree of congruence between patient preferences for the clinical encounter and reports of analogous dimensions of provider behavior and the effects of this congruence on patient outcomes. Two hundred eighteen patients with diabetes (predominately Type II) completed measures of preference for and ratings of perceived provider behavior in three domains (1) information sharing, (2) behavioral involvement, and (3) socioemotional support. Patient satisfaction, self-reported adherence, and a clinical marker of diabetic control (hemoglobin A1c) were the outcomes of interest. Congruence in information sharing and congruence in behavioral involvement were predictive of glycemic control and self-reported adherence, respectively. Congruence in behavioral involvement and congruence in socioemotional support were predictive of greater patient satisfaction. These findings provide further support for the importance of congruence between patient characteristics and contextual characteristics in predicting patient outcomes.

Symmetric systems of van der Pol equations

We study the impact of symmetries on the occurrence of periodic solutions in systems of van der Pol equations. We apply the equivariant degree theory to establish existence results for multiple nonconstant periodic solutions and classify their symmetries. The computations of the algebraic invariants in the case of dihedral, tetrahedral, octahedral and icosahedral symmetries for a van der Pol system of equations are included.

Core-modified porphyrins. Part 4: Steric effects on photophysical and biological properties in vitro

21,23-Dithiaporphyrins ( 2– 10) were designed and prepared as analogues of 5,20-diphenyl-10,15-bis(4-carboxylatomethoxy)phenyl-21,23-dithiaporphyrin ( 1) to examine the impact of steric bulk at the 5- and 20- meso positions as well as the impact of symmetry. Changes at the meso positions had minimal impact on the UV–vis–near-IR absorption spectra, quantum yields for the generation of singlet oxygen, and quantum yields for fluorescence and some impact on values of the octanol/water partition coefficient. Of the compounds 1– 10, 5-phenyl-20-(2-thienyl)-10,15-bis-(4-carboxylatomethoxy-phenyl)-21,23-dithiaporphyrin ( 3) showed the greatest phototoxicity toward cultured R3230AC cells, with 68% cell kill at 1 × 10 −7 M and irradiation with 5 J cm −2 of 350–750 nm light. Results in this study suggest that smaller substituents on the meso ring and less symmetrical compounds are more effective as photosensitizers than compounds with two bulky substituents at adjoining meso sites and a higher symmetry. The mitochondria appear to be involved in the process of phototoxicity as determined by the inhibition of whole cell cytochrome c oxidase activity in cells treated with 3 and light. No impact upon mitochondrial cytochrome c oxidase activity was observed in cells treated with 3 and no light. Fluorescence microscopy studies suggest that the mitochondria are not initial sites of accumulation of 3.

Potentiometric quasi-array employing calixarene derivatives for the high-throughput similarity/diversity screening of beta-adrenergic and beta-blocking chiral drugs by HPLC.

Performance of potentiometric quasi-array detection system consisted with the seven poly (vinyl chloride) (PVC) based liquid membrane electrodes in the cation-exchange HPLC using acetonitrile--40 mM phosphoric acid (15 : 85, v/v, pH* 2.35) for assessing of molecular similarity/diversity in a mini-library of beta-adrenergic and beta-blocking chiral drugs was presented. Macrocyclic compounds differing in stability of their conformers as well as in a size, steric hindrance and polarity of its internal cavities, comprising a series of five calix[6]arene derivatives completed with one modified calix[4]resorcinarene, were used as neutral ionophores to compose mentioned set of PVC-based electrodes. The output potentiometric responses were registered in the linear supernerstian range of calibration graph of each electrode, i.e. for a constant injected concentration 2.0 x 10(-4) M of investigated drugs, which is related to the amount frequently used at in vitro studies on pharmacological effects of these drugs. The impact of symmetry oriented supramolecular interactions on the responses of developed electrodes were characterised with proposed series of the highly significant quantitative structure-potentiometric response relationships (QSPRRs) combining both three-dimensional (3D) molecular descriptors of analysed drugs as well as lipophilicity and volume polarizability of calixarene-type ionophores. The principal components analysis (PCA) and unweighted hierarchical clustering analysis (HCA) were used as the pattern recognition techniques into collected potentiometric database for extraction of the useful information on the molecular and pharmacological similarity/diversity of analysed drugs, thus a high-throughput and consistent identification of therapeutically relevant agonists of beta2- and beta3-adrenoceptors and antagonists of beta1-adrenoceptor was especially achieved. This evidence supports also a hypothesis formulated by results of homology modelling on the subtle significance of an unrecognised supramolecular insertion processes of the chiral drug molecule into the flexible hydrophobic pocket(s) formed by seven helical transmembrane moving domains of beta-adrenoceptors on their final activation, sequestration, down-regulation or blockade.

The Impact of Symmetry on Software Distributed Shared Memory

A homeless protocol is one in which all nodes are treated identically when they access common resources. By contrast, home-based protocols assign a home or manager to each resource. Use of the resource by the home incurs less overhead than use by other processors. The key to good performance in such systems is to ensure that the asymmetry of the underlying protocol is skewed in the same way as that of the application. This paper presents a comparative evaluation of invalidation-based homeless and home-based software DSM protocols. We pay particular attention to those performance differences caused by symmetric and asymmetric features of the protocols. We then show how the picture changes when update protocols are targeted. We show that a modified home-based protocol can significantly outperform more general protocols in this application domain because of reduced protocol complexity. We further optimize our protocol by completely eliminating such memory manipulation calls from the steady-state execution. Our resulting protocol improves average application performance by a further 34%, on top of the 19% improvement gained by our initial modification of the home-based protocol.