16,726 research outputs found
Antimagnetic Rotation Band in Nuclei: A Microscopic Description
Covariant density functional theory and the tilted axis cranking method are
used to investigate antimagnetic rotation (AMR) in nuclei for the first time in
a fully self-consistent and microscopic way. The experimental spectrum as well
as the B(E2) values of the recently observed AMR band in 105Cd are reproduced
very well. This gives a further strong hint that AMR is realized in specific
bands in nuclei.Comment: 10 pages, 4 figure
Progress on tilted axis cranking covariant density functional theory for nuclear magnetic and antimagnetic rotation
Magnetic rotation and antimagnetic rotation are exotic rotational phenomena
observed in weakly deformed or near-spherical nuclei, which are
respectivelyinterpreted in terms of the shears mecha-nism and two shearslike
mechanism. Since their observations, magnetic rotation and antimagnetic
rotation phenomena have been mainly investigated in the framework of tilted
axis cranking based on the pairing plus quadrupole model. For the last decades,
the covariant density functional theory and its extension have been proved to
be successful in describing series of nuclear ground-states and excited states
properties, including the binding energies, radii, single-particle spectra,
resonance states, halo phenomena, magnetic moments, magnetic rotation,
low-lying excitations, shape phase transitions, collective rotation and
vibrations, etc. This review will mainly focus on the tilted axis cranking
covariant density functional theory and its application for the magnetic
rotation and antimagnetic rotation phenomena.Comment: 53 pages, 19 figure
The Adversarial Attack and Detection under the Fisher Information Metric
Many deep learning models are vulnerable to the adversarial attack, i.e.,
imperceptible but intentionally-designed perturbations to the input can cause
incorrect output of the networks. In this paper, using information geometry, we
provide a reasonable explanation for the vulnerability of deep learning models.
By considering the data space as a non-linear space with the Fisher information
metric induced from a neural network, we first propose an adversarial attack
algorithm termed one-step spectral attack (OSSA). The method is described by a
constrained quadratic form of the Fisher information matrix, where the optimal
adversarial perturbation is given by the first eigenvector, and the model
vulnerability is reflected by the eigenvalues. The larger an eigenvalue is, the
more vulnerable the model is to be attacked by the corresponding eigenvector.
Taking advantage of the property, we also propose an adversarial detection
method with the eigenvalues serving as characteristics. Both our attack and
detection algorithms are numerically optimized to work efficiently on large
datasets. Our evaluations show superior performance compared with other
methods, implying that the Fisher information is a promising approach to
investigate the adversarial attacks and defenses.Comment: Accepted as an AAAI-2019 oral pape
Enantioselective Total Synthesis of Macfarlandin C, a Spongian Diterpenoid Harboring a Concave-Substituted cis-Dioxabicyclo[3.3.0]octanone Fragment.
The enantioselective total synthesis of the rearranged spongian diterpenoid (-)-macfarlandin C is reported. This is the first synthesis of a rearranged spongian diterpenoid in which the bulky hydrocarbon fragment is joined via a quaternary carbon to the highly hindered concave face of the cis-2,8-dioxabicyclo[3.3.0]octan-3-one moiety. The strategy involves a late-stage fragment coupling between a tertiary carbon radical and an electrophilic butenolide resulting in the stereoselective formation of vicinal quaternary and tertiary stereocenters. A stereoselective Mukaiyama hydration that orients a pendant carboxymethyl side chain cis to the bulky octahydronapthalene substituent was pivotal in fashioning the challenging concave-substituted cis-dioxabicyclo[3.3.0]octanone fragment
Fighting For Time: Spillover and Crossover Effects of Long Work Hours Among Dual-Earner Couples
Drawing upon the spillover-crossover model, this study examined the extent to which one\u27s work time demands spilled over to the family domain, and crossed over to his or her spouse, utilizing data of 365 dual-earner couples from the 500 Family Study. The results of the distinguishable actor-partner interdependence model indicated that there was gender symmetry in the spillover processes such that the effects of work hours were identical between men and women. Further, although there was more bi-directional crossover between partners within couples, we observed some unidirectional crossover from husbands to wives. Specifically, husbands only increased their contribution to domestic work in response to wives\u27 work fatigue, whereas wives increased their contribution to domestic work in response to husbands\u27 work fatigue and high workloads. Finally, husbands\u27 housework hours negatively related to wives\u27 marital satisfaction and positively related to wives\u27 depression, whereas wives\u27 housework hours negatively related to husbands\u27 marital satisfaction and depression. These findings have practical implications for improving the work-family balance, health, and well-being of dual-earner couples
Covariant density functional theory for antimagnetic rotation
Following the previous letter on the first microscopic description of the
antimagnetic rotation (AMR) in 105Cd, a systematic investigation and detailed
analysis for the AMR band in the frame-work of tilted axis cranking (TAC) model
based on covariant density functional theory are carried out. After performing
the microscopic and self-consistentTAC calculations with an given density
functional, the configuration for the observed AMR band in 105Cd is obtained
from the single-particle Routhians. With the configuration thus obtained, the
tilt angle for a given rotational frequency is determined self-consistently by
minimizing the total Routhian with respect to the tilt angle. In such a way,
the energy spectrum, total angular momenta, kinetic and dynamic moments of
inertia, and the B(E2) values for the AMR band in 105Cd are calculated. Good
agreement with the data is found. By investigating microscopically the
contributions from neutrons and protons to the total angular momentum, the
"two-shears-like" mechanism in the AMR band is clearly illus-trated. Finally,
the currents leading to time-odd mean fields in the Dirac equation are
presented and discussed in detail. It is found that they are essentially
determined by the valence particles and/or holes. Their spatial distribution
and size depend onthe specific single-particle orbitals and the rotational
frequency.Comment: 35 pages, 17 figures, accepted by Phys. Rev.
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