SU(4) symmetry in the extended proton-neutron interacting boson model: multiplets and symmetry breaking

The manifestation of $SU(4)$ symmetry within an interacting boson model including particle-like and hole-like $\pi$- and $\nu$-bosons is shown for light nuclei around the Z=N=8 shell. We also present a consistent description of the particle-hole (intruder spin or $I$ spin) multiplets in the Extended Interacting Boson Model (EIBM) and of $\pi$-$\nu$ ($F$ spin) multiplets in the IBM-2 as a breaking of this $SU(4)$ symmetry

New particle-hole symmetries and the extended interacting boson model

We describe shape coexistence and intruder many-particle-hole (mp-nh)excitations in the extended interacting boson model EIBM and EIBM-2,combining both the particle-hole and the charge degree of freedom.Besides the concept of I-spin multiplets and subsequently $SU(4)$ multiplets, we touch upon the existence of particle-hole mixed symmetry states. We furthermore describe regular and intrudermany-particle-hole excitations in one nucleus on an equal footing, creating (annihilating) particle-hole pairs using the K-spin operatorand studying possible mixing between these states. As a limiting case,we treat the coupling of two IBM-1 Hamiltonians, each decribing the regular and intruder excitations respectively, in particular lookingat the $U(5)$-$SU(3)$ dynamical symmetry coupling. We apply such coupling scheme to the Po isotopes

Shape coexistence in atomic nuclei and its spectroscopic fingerprints

In the present discussion we concentrate on shape coexistence asobtained within a deformed single-particle field as well as startingfrom the spherical shell-model, incorporating deformationeffects via the residual proton-neutron quadrupole interaction. Wediscuss in particular the appearance of shape coexisting phenomena inthe Pb region. In a second part then, we present a number ofexperimental fingerprints that allow to recognize the appearance ofshape coexisting phenomena or of shape mixing through the use ofselective experiments (e.g. band structure, spectroscopic factors,static moments, E0 properties and alpha-decay)

Particle-hole excitations in the interacting boson model; 4, the U(5)-SU(3) coupling

In the extended interacting boson model (EIBM) both particle- and hole-like bosons are incorporated to encompass multi-particle-multi-hole excitations at and near to closed shells.We apply the group theoretical concepts of the EIBM to the particular case of two coexisting systems in the same nucleus exhibiting a U(5) (for the regular configurations) and an SU(3) symmetry (for the intruder configurations).Besides the description of ``global'' symmetry aspects in terms of I-spin , also the very specific local mixing effects characteristic for the U(5)-SU(3) symmetry coupling are studied.The model is applied to the Po isotopes and a comparison with a morerealistic calculation is made

Planetary Boundary Layer Simulation Using TASS

Boundary conditions to an existing large-eddy simulation model have been changed in order to simulate turbulence in the atmospheric boundary layer. Several options are now available, including the use of a surface energy balance. In addition, we compare convective boundary layer simulations with the Wangara and Minnesota field experiments as well as with other model results. We find excellent agreement of modelled mean profiles of wind and temperature with observations and good agreement for velocity variances. Neutral boundary simulation results are compared with theory and with previously used models. Agreement with theory is reasonable, while agreement with previous models is excellent

The Sensitivity of Large-Eddy Simulation to Local and Nonlocal Drag Coefficients at the Lower Boundary

It was found that the homogeneity of the surface drag coefficient plays an important role in the large scale structure of turbulence in large-eddy simulation of the convective atmospheric boundary layer. Particularly when a ground surface temperature was specified, large horizontal anisotropies occurred when the drag coefficient depended upon local velocities and heat fluxes. This was due to the formation of streamwise roll structures in the boundary layer. In reality, these structures have been found to form when shear is approximately balanced by buoyancy. The present cases, however, were highly convective. The formation was caused by particularly low values of the drag coefficient at the entrance to thermal plume structures

Inferring Accountability from Trust Perceptions

International audienceOpaque communications between groups of data processors leave individuals out of touch with the circulation and use of their personal information. Empowering individuals in this regard requires sup-plying them — or auditors on their behalf — with clear data handling guarantees. We introduce an inference model providing individuals with global (organization-wide) accountability guarantees which take into account user expectations and varying levels of usage evidence, such as data handling logs. Our model is implemented in the IDP knowledge base system and demonstrated with the scenario of a surveillance infrastructure used by a railroad company. We show that it is flexible enough to be adapted to any use case involving communicating stakeholders for which a trust hierarchy is defined. Via auditors acting for them, individuals can obtain global accountability guarantees, providing them with a trust-dependent synthesis of declared and proven data handling practices for an entire organization

The acute effects of cocoa flavanols on temporal and spatial attention

In this study, we investigated how the acute physiological effects of cocoa flavanols might result in specific cognitive changes, in particular in temporal and spatial attention. To this end, we pre-registered and implemented a randomized, double-blind, placebo- and baseline-controlled crossover design. A sample of 48 university students participated in the study and each of them completed the experimental tasks in four conditions (baseline, placebo, low dose, and high-dose flavanol), administered in separate sessions with a 1-week washout interval. A rapid serial visual presentation task was used to test flavanol effects on temporal attention and integration, and a visual search task was similarly employed to investigate spatial attention. Results indicated that cocoa flavanols improved visual search efficiency, reflected by reduced reaction time. However, cocoa flavanols did not facilitate temporal attention nor integration, suggesting Potential underlying mechanisms are discussed