Two Particle Azimuthal Correlations in 4.2A GeV C+Ta Collisions

Two particle azimuthal correlations are studied in 4.2A GeV C+Ta collisions observed with the 2-m propane bubble chamber exposed at JINR Dubna Synchrophasotron. The correlations are analyzed both for protons and negative pions, and their dependence on the collision centrality, rapidity and rapidity difference is investigated. It is found that protons show a weak back-to-back correlations, while a side-by-side correlations are observed for negative pions. Restricting both protons to the target or projectile fragmentation region, the side-by-side correlations are observed for protons also. Using the two particle correlation function, the flow analysis is performed and intensity of directed flow is determined without event-by event estimation of the reaction plane.Comment: 4 pages, 3 figure

Masses of constituent quarks confined in open bottom hadrons

We apply color-spin and flavor-spin quark-quark interactions to the meson and baryon constituent quarks, and calculate constituent quark masses, as well as the coupling constants of these interactions. The main goal of this paper was to determine constituent quark masses from light and open bottom hadron masses, using the fitting method we have developed and clustering of hadron groups. We use color-spin Fermi-Breit (FB) and flavor-spin Glozman-Riska (GR) hyperfine interaction (HFI) to determine constituent quark masses (especially $b$ quark mass). Another aim was to discern between the FB and GR HFI because our previous findings had indicated that both interactions were satisfactory. Our improved fitting procedure of constituent quark masses showed that on average color-spin (Fermi-Breit) hyperfine interaction yields better fits. The method also shows the way how the constituent quark masses and the strength of the interaction constants appear in different hadron environments.Comment: 15 pages, 6 tables, 1 figure. Accepted for publication in Mod. Phys. Lett.

APPRAISAL OF FAMILIARITY WITH CONTENT: ITS RELATIONSHIP WITH DIMENSIONS OF EMOTIONAL EXPERIENCE

The aim of this study was to examine the relationship between the dimensions of the emotional experience (valence and arousal), the quality of emotions (happiness, sadness, fear, anger, surprise, and disgust), and the appraisal of familiarity with content. Ninety-two participants assessed how familiar the content of the 40 photographs were to them. The photographs were selected from the NAPS database and systematically varied along the dimensions and qualities of the emotional experience. Statistically significant correlations were obtained between the appraisal of familiarity and the dimensions of the emotional experience. The correlation of familiarity appraisal with arousal was negative, unlike findings from earlier studies. Significant positive correlation with happiness and negative correlations with sadness, fear, surprise, anger, and disgust were also found

Distinct magnetic signatures of fractional vortex configurations in multiband superconductors

Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, we examine such vortex configurations in a two-band superconducting slab in parallel magnetic field. The fractional vortices appear due to the band-selective vortex penetration caused by different thresholds for vortex entry within each band-condensate, and stabilize near the edges of the sample. We show that the resulting fractional vortex configurations leave distinct fingerprints in the static measurements of the magnetization, as well as in ac dynamic measurements of the magnetic susceptibility, both of which can be readily used for the detection of these fascinating vortex states in several existing multiband superconductors.Comment: 5 pages, 4 figure

Unstable compared to stable core exercises improve muscular endurance in preadolescents and adolescents: An eight-month randomized trial

Although previous studies have indicated the importance of a core strength and muscular endurance training in preadolescents and adolescents, there is a lack of evidence regarding effects of a long-term core training in unstable conditions. The purpose of this study was to compare the effects of core training in stable versus unstable body positions on core and upper body strength and muscular endurance in non-trained children aged 11-14 years. Participants were randomly assigned to either stable (SC, N=569) or unstable (UC, N=633) core-exercise group and assessed at baseline, after four, and eight months for sit-ups, dynamic trunk extension, static trunk extension, and push-ups. Repeated measures ANOVA, with time as a within factor, and exercise group, age, and gender as between factors, was employed for data analysis. Post-hoc comparisons showed greater absolute improvements after the eight-month training in UC compared to SC for all measures, age groups, and both genders (p≤.01), and greater relative improvements (differences in Cohen’s d between UC and SC ranged from 0.08 to 1.58), except for static trunk extension in 11- and 12-year-old participants. However, the differences between SC and UC in four-month effects were inconsistent. These results point out that core exercises in unstable compared to stable conditions have a greater capacity for long-term improvement of core and upper body strength and muscular endurance in non-trained preadolescents and adolescents

Competing symmetries and broken bonds in superconducting vortex-antivortex molecular crystals

Hall probe microscopy has been used to image vortex-antivortex molecules induced in superconducting Pb films by the stray fields from square arrays of magnetic dots. We have directly observed spontaneous vortex-antivortex pairs and studied how they interact with added free (anti)fluxons in an applied magnetic field. We observe a variety of phenomena arising from competing symmetries which either drive added antivortices to join antivortex shells around dots or stabilize the translationally symmetric antivortex lattice between the dots. Added vortices annihilate antivortex shells, leading first to a stable “nulling state” with no free fluxons and then, at high densities, to vortex shells around the dots stabilized by the asymmetric antipinning potential. Our experimental findings are in good agreement with Ginzburg-Landau calculations

Conditions for non-monotonic vortex interaction in two-band superconductors

We describe a semi-analytic approach to the two-band Ginzburg-Landau theory, which predicts the behavior of vortices in two-band superconductors. We show that the character of the short-range vortex-vortex interaction is determined by the sign of the normal domain - superconductor interface energy, in analogy with the conventional differentiation between type-I and type-II superconductors. However, we also show that the long-range interaction is determined by a modified Ginzburg-Landau parameter $\kappa^*$, different from the standard $\kappa$ of a bulk superconductor. This opens the possibility for non-monotonic vortex-vortex interaction, which is temperature-dependent, and can be further tuned by alterations of the material on the microscopic scale

Magnetic Pinning of Vortices in a Superconducting Film: The (anti)vortex-magnetic dipole interaction energy in the London approximation

The interaction between a superconducting vortex or antivortex in a superconducting film and a magnetic dipole with in- or out-of-plane magnetization is investigated within the London approximation. The dependence of the interaction energy on the dipole-vortex distance and the film thickness is studied and analytical results are obtained in limiting cases. We show how the short range interaction with the magnetic dipole makes the co-existence of vortices and antivortices possible. Different configurations with vortices and antivortices are investigated.Comment: 12 pages, 12 figures. Submitted to Phys. Rev.

Carbon Nanotubes Band Assignation, Topology, Bloch States and Selection Rules

Various properties of the energy band structures (electronic, phonon, etc.), including systematic band degeneracy, sticking and extremes, following from the full line group symmetry of the single-wall carbon nanotubes are established. The complete set of quantum numbers consists of quasi momenta (angular and linear or helical) and parities with respect to the z-reversal symmetries and, for achiral tubes, the vertical plane. The assignation of the electronic bands is performed, and the generalized Bloch symmetry adapted eigen functions are derived. The most important physical tensors are characterized by the same set of quantum numbers. All this enables application of the presented exhaustive selection rules. The results are discussed by some examples, e.g. allowed interband transitions, conductivity, Raman tensor, etc.Comment: 11 pages, 2 figures, 2 tables; pdf available from: http://www.ff.bg.ac.yu/qmf/qsg_e.ht

Dimensional crossover and incipient quantum size effects in superconducting niobium nanofilms

Superconducting and normal state properties of sputtered Niobium nanofilms have been systematically investigated, as a function of film thickness in a d=9-90 nm range, on different substrates. The width of the superconducting-to-normal transition for all films remained in few tens of mK, thus remarkably narrow, confirming their high quality. We found that the superconducting critical current density exhibits a pronounced maximum, three times larger than its bulk value, for film thickness around 25 nm, marking the 3D-to-2D crossover. The extracted magnetic penetration depth shows a sizeable enhancement for the thinnest films, aside the usual demagnetization effects. Additional amplification effects of the superconducting properties have been obtained in the case of sapphire substrates or squeezing the lateral size of the nanofilms. For thickness close to 20 nm we also measured a doubled perpendicular critical magnetic field compared to its saturation value for d>33 nm, indicating shortening of the correlation length and the formation of small Cooper pairs in the condensate. Our data analysis evidences an exciting interplay between quantum-size and proximity effects together with strong-coupling effects and importance of disorder in the thinnest films, locating the ones with optimally enhanced critical properties close to the BCS-BEC crossover regime