3,133 research outputs found
Testing functional hypotheses about cross-cultural variation: A maximum-likelihood comparative analysis of Indo-European marriage practices
From bridewealth to dowry? A Bayesian estimation of ancestral states of marriage transfers in Indo-European groups
Significant amounts of wealth have been exchanged as part of marriage settlements throughout history. Although various models have been proposed for interpreting these practices, their development over time has not been investigated systematically. In this paper we use a Bayesian MCMC phylogenetic comparative approach to reconstruct the evolution of two forms of wealth transfers at marriage, dowry and bridewealth, for 51 Indo-European cultural groups. Results indicate that dowry is more likely to have been the ancestral practice, and that a minimum of four changes to bridewealth is necessary to explain the observed distribution of the two states across the cultural groups
Pairing in the continuum: the quadrupole response of the Borromean nucleus 6He
The ground state and low-lying continuum states of 6He are found within a
shell model scheme, in a basis of two-particle states built out of continuum
p-states of the unbound 5He nucleus, using a simple pairing contact-delta
interaction. This accounts for the Borromean character of the bound ground
state, revealing its composition. We investigate the quadrupole response of the
system and we put our calculations into perspective with the latest
experimental results. The calculated quadrupole strength distribution
reproduces the narrow 2+ resonance, while a second wider peak is found at about
3.9 MeV above the g.s. energy.Comment: 5 pages, 5 figure
Electric multipole response of the halo nucleus He
The role of different continuum components in the weakly-bound nucleus He
is studied by coupling unbound spd-waves of He by means of simple pairing
contact-delta interaction. The results of our previous investigations in a
model space containing only p-waves, showed the collective nature of the ground
state and allowed the calculation of the electric quadrupole transitions. We
extend this simple model by including also sd-continuum neutron states and we
investigate the electric monopole, dipole and octupole response of the system
for transitions to the continuum, discussing the contribution of different
configurations.Comment: 22 pages, 10 figure
Electric and magnetic response to the continuum for A=7 isobars in a dicluster model
Mirror isobars Li and Be are investigated in a dicluster model. The
magnetic dipole moments and the magnetic dipole response to the continuum are
calculated in this framework. The magnetic contribution is found to be small
with respect to electric dipole and quadrupole excitations even at
astrophysical energies, at a variance with the case of deuteron. Energy
weighted molecular sum rules are evaluated and a formula for the molecular
magnetic dipole sum rule is found which matches the numerical calculations.
Cross-sections for photo-dissociation and radiative capture as well as the
S-factor for reactions of astrophysical significance are calculated with good
agreement with known experimental data.Comment: Accepted in EPJ
Study of Giant Pairing Vibrations with neutron-rich nuclei
We investigate the possible signature of the presence of giant pairing states
at excitation energy of about 10 MeV via two-particle transfer reactions
induced by neutron-rich weakly-bound projectiles. Performing particle-particle
RPA calculations on Pb and BCS+RPA calculations on Sn, we
obtain the pairing strength distribution for two particles addition and removal
modes. Estimates of two-particle transfer cross sections can be obtained in the
framework of the 'macroscopic model'. The weak-binding nature of the projectile
kinematically favours transitions to high-lying states. In the case of (~^6He,
\~^4He) reaction we predict a population of the Giant Pairing Vibration with
cross sections of the order of a millibarn, dominating over the mismatched
transition to the ground state.Comment: Talk presented in occasion of the VII School-Semina r on Heavy Ion
Physics hosted by the Flerov Laboratory (FLNR/JINR) Dubna, Russia from May 27
to June 2, 200
The macro-behavior of agents' opinion under the influence of an external field
In this paper, a model about the evolution of opinion on small world networks
is proposed. We studied the macro-behavior of the agents' opinion and the
relative change rate as time elapses. The external field was found to play an
important role in making the opinion balance or increase, and without
the influence of the external field, the relative change rate shows
a nonlinear increasing behavior as time runs. What's more, this nonlinear
increasing behavior is independent of the initial condition, the strength of
the external field and the time that we cancel the external field. Maybe the
results can reflect some phenomenon in our society, such as the function of the
macro-control in China or the Mass Media in our society.Comment: 8 pages, 3 figure
Soft triaxial roto-vibrational motion in the vicinity of
A solution of the Bohr collective hamiltonian for the soft,
soft triaxial rotor with is presented making use
of a harmonic potential in and Coulomb-like and Kratzer-like
potentials in . It is shown that, while the angular part in the
present case gives rise to a straightforward extension of the rigid triaxial
rotor energy in which an additive harmonic term appears, the inclusion of the
part results instead in a non-trivial expression for the spectrum. The
negative anharmonicities of the energy levels with respect to a simple rigid
model are in qualitative agreement with general trends in the experimental
data.Comment: 4 pages, 2 figures, accepted in Phys.Rev.
Ranking and clustering of nodes in networks with smart teleportation
Random teleportation is a necessary evil for ranking and clustering directed
networks based on random walks. Teleportation enables ergodic solutions, but
the solutions must necessarily depend on the exact implementation and
parametrization of the teleportation. For example, in the commonly used
PageRank algorithm, the teleportation rate must trade off a heavily biased
solution with a uniform solution. Here we show that teleportation to links
rather than nodes enables a much smoother trade-off and effectively more robust
results. We also show that, by not recording the teleportation steps of the
random walker, we can further reduce the effect of teleportation with dramatic
effects on clustering.Comment: 10 pages, 7 figure
Photogrammetry for digital reconstruction of railway ballast particles – a cost-efficient method
Ballast aggregate is a natural material widely used in railway lines. Its mechanical properties and particle geometry are meticulously defined using well-established standards and characterisation procedures. Though extensively validated, these procedures have some limitations: they are operator dependent; only provide major particle dimensions; do not inform on surface colour; nor allow for advanced particle wear analysis or particle-based simulations. This work presents a cost-efficient photogrammetry method for 3D reconstruction of ballast particles, as an alternative to the significantly expensive laser scanning. It produces digital models of equivalent or higher quality, allowing for advanced and automated particle geometry analyses. Particle meshes produced here are shared among researchers.info:eu-repo/semantics/acceptedVersio
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