Effect of the Eley-Rideal step on catalytic oxidation of CO under periodic external pressure

The effect of periodic variation of external pressure on the catalytic oxidation of CO is simulated for a modified Ziff-Gulari-Barshad (ZGB) model including the Eley-Rideal (ER) step. The external CO partial pressure is periodically varied between its values in reactive and CO poisoned states. The results show different amplitudes of such perturbation significantly influence the CO₂ production rate. Latter also changes with the period of such oscillations, especially for perturbations with larger amplitudes. However, for a given period there is a critical value of the amplitude above which, the catalyst surface becomes irreversibly poisoned.     

Reaction functions for weakly bound systems

We propose a new technique to analyze total reaction cross sections. In this technique, which has been previously applied to fusion reactions, the experimental data are used to build a dimensionless reaction function, which does not depend on the system size or details of the optical potential. In this way, total reaction cross sections for different systems can be directly compared. We employ this technique to perform a systematic study of reaction cross sections of weakly bound systems in different mass ranges, and compare their reaction functions with the ones of tightly bound systems with similar masses. We show that breakup reactions and neutron transfers in halo systems lead to large reaction functions, well above the ones of typical tightly or weakly bound stable systems.     

Topics in Noncommutative Geometry Inspired Physics

In this review article we discuss some of the applications of noncommutative geometry in physics that are of recent interest, such as noncommutative many-body systems, noncommutative extension of Special Theory of Relativity kinematics, twisted gauge theories and noncommutative gravity.     

Moving curves of the sine-Gordon equation: New links

We provide a general scheme for mapping integrable nonlinear partial differential equations of real functions to moving space curves using an approach different from the one proposed by Lamb. We apply our method to the sine-Gordon equation and obtain links to five new classes of space curves, in addition to the two found by Lamb. For each class, we display the rich variety of moving curves associated with the one-soliton, the breather, the two-soliton and the soliton-antisoliton solutions, and suggest possible applications. Our results also provide new insights with regard to the two-soliton (soliton-antisoliton) scattering process.     

Phased array 3D MR spectroscopic imaging of the brain at 7 T

Ultra-high-field 7 T magnetic resonance (MR) scanners offer the potential for greatly improved MR spectroscopic imaging due to increased sensitivity and spectral resolution. Prior 7 T human single-voxel MR Spectroscopy (MRS) studies have shown significant increases in signal-to-noise ratio (SNR) and spectral resolution as compared to lower magnetic fields but have not demonstrated the increase in spatial resolution and multivoxel coverage possible with 7 T MR spectroscopic imaging. The goal of this study was to develop specialized radiofrequency (RF) pulses and sequences for three-dimensional (3D) MR spectroscopic imaging (MRSI) at 7 T to address the challenges of increased chemical shift misregistration, B1 power limitations, and increased spectral bandwidth. The new 7 T MRSI sequence was tested in volunteer studies and demonstrated the feasibility of obtaining high-SNR phased-array 3D MRSI from the human brain.     

First Penning trap mass measurements beyond the proton drip line

The masses of six neutron-deficient rare holmium and thulium isotopes close to the proton drip line were determined with the SHIPTRAP Penning trap mass spectrometer. For the first time the masses of the proton-unbound isotopes 144,145Ho and 147,148Tm were directly measured. The proton separation energies were derived from the measured mass values and compared to predictions from mass formulas. The new values of the proton separation energies are used to determine the location of the proton drip line for holmium and thulium more accurately.     

Spatial line nodes and fractional vortex pairs in the Fulde-Ferrell-Larkin-Ovchinnikov vortex state of spin-singlet superconductors

A Zeeman magnetic field can induce a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase in spin-singlet superconductors. Here we argue that there is a nontrivial solution for the FFLO vortex phase that exists near the upper critical field in which the wave function has only spatial line nodes that form intricate and unusual three-dimensional structures. These structures include a crisscrossing lattice of two sets of nonparallel line nodes. We show that these solutions arise from the decay of conventional Abrikosov vortices into pairs of fractional vortices. We propose that neutron scattering studies can observe these fractional vortex pairs through the observation of a lattice of 1/2 flux quanta vortices. We also consider related phases in noncentrosymmetric superconductors.     

Structure of neutron-rich Ar isotopes beyond N = 28

Results from the gamma-ray spectroscopy of {47,48}Ar exemplifying new limits of sensitivity for characterizing neutron-rich nuclei at energies around the Coulomb barrier are presented. The present results, along with interacting shell model calculations, highlight the role of cross-shell excitations and indicate the presence of a nonaxial deformation in 48Ar.     

Lattice quantum chromodynamics equation of state: A better differential method

We propose a better differential method for the computation of the equation of state of QCD from lattice simulations. In contrast to the earlier differential method, our technique yields positive pressure for all temperatures including the temperatures in the transition region. Employing it on temporal lattices of 8, 10 and 12 sites and by extrapolating to zero lattice spacing we obtained the pressure, energy density, entropy density, specific heat and speed of sound in quenched QCD for 0.9 ≤ T/T _c ≤ 3. At high temperatures comparisons of our results are made with those from the dimensional reduction approach and also with those from a conformal symmetric theory.