Perturbation theory is used systematically to investigate the symmetries of the Dirac Hamiltonian and their breaking in atomic nuclei. Using the perturbation corrections to the single-particle energies and wave functions, the link between the single-particle states in realistic nuclei and their counterparts in the symmetry limits is discussed. It is shown that the limit of S-V=const and relativistic harmonic oscillator (RHO) potentials can be connected to the actual Dirac Hamiltonian by the perturbation method, while the limit of S+V=const cannot, where S and V are the scalar and vector potentials, respectively. This indicates that the realistic system can be treated as a perturbation of spin-symmetric Hamiltonians, and the energy splitting of the pseudospin doublets can be regarded as a result of small perturbation around the Hamiltonian with RHO potentials, where the pseudospin doublets are quasidegenerate.Comment: 5 pages, 4 figures, Phys. Rev. C in pres

We study the shape evolution of C isotopes in the full (β, γ) deformation plane using a constrained Skyrme Hartree-Fock + BCS method in coordinate space. It is shown that the deformation of the energy minimum varies markedly in the (β, γ) plane as a function of mass number, which can be viewed as a clear manifestation of the spontaneous symmetry breaking effect in finite many-body systems. We also study the difference in deformations between protons and neutrons in the total (β, γ) plane. It is found that the proton and neutron quadrupole moments are almost the same in light C isotopes, while the neutron quadrupole moment is about 3 times larger than the proton one in C isotopes heavier than 16 C. The isospin symmetry of the mirror nuclei 10 C and 10 Be is also examined in connection with the deformation in the (β, γ) plane.

BackgroundDiabetic retinopathy is a microvascular neurodegenerative disorder in diabetic patients. Peripapillary retinal nerve fiber layer changes have been described in patients with preclinical diabetic retinopathy, but study results have been inconsistent.ObjectiveTo assess changes in peripapillary retinal nerve fiber layer thickness in diabetic patients with preclinical diabetic retinopathy.MethodsA literature search was conducted through PubMed, EMBASE, Web of Science and Cochrane Library. Case-control studies on RNFL thickness in preclinical diabetic retinopathy patients and healthy controls were retrieved. A meta-analysis of weighted mean difference and a sensitivity analysis were performed using RevMan 5.2 software.ResultsThirteen case-control studies containing 668 diabetic patients and 556 healthy controls were selected. Peripapillary RNFL thickness was significantly reduced in patients with preclinical diabetic retinopathy compared to healthy controls in studies applying Optical Coherence Tomography (-2.88μm, 95%CI: -4.44 to -1.32, P = 0.0003) and in studies applying Scanning Laser Polarimeter (-4.21μm, 95%CI: -6.45 to -1.97, P = 0.0002). Reduction of RNFL thickness was significant in the superior quadrant (-3.79μm, 95%CI: -7.08 to -0.50, P = 0.02), the inferior quadrant (-2.99μm, 95%CI: -5.44 to -0.54, P = 0.02) and the nasal quadrant (-2.88μm, 95%CI: -4.93 to -0.82, P = 0.006), but was not significant in the temporal quadrant (-1.22μm, 95%CI: -3.21 to 0.76, P = 0.23), in diabetic patients.ConclusionPeripapillary RNFL thickness was significantly decreased in preclinical diabetic retinopathy patients compared to healthy control. Neurodegenerative changes due to preclinical diabetic retinopathy need more attention.

The study investigated the effect of mini-trampoline physical activity on the development of executive functions (EF) in Chinese preschool children. Fifty-seven children aged 3–5 were randomly assigned to an intervention group (n = 29) and a control group (n = 28). The children in the intervention and control group had the same classes and care service in the preschool, but children in the intervention group had an extra 20 min of trampoline training after school for 5 school days per week in the 10-week intervention. Spatial conflict arrow (SCA), animal Go/NoGo (GNG), working memory span (WMS), and flexible item selection (FIS) were used to assess children's EF before and after the intervention. Results revealed that no significant differences emerged in the SCA, GNG, WMS, and FIS tests between two groups postintervention. Findings indicated that a 10-week trampoline PA training may not be sufficient to trigger the improvement of preschool children's EF. Future research with larger representative samples is warranted to discern the dose-response evidence in enhancing young children's EF through physical activity.