5,096 research outputs found
Multidimensional generalized Gini indices.
The axioms used to characterize the generalized Gini social evaluation orderings for one-dimensional distributions are extended to the multidimensional attributes case. A social evaluation ordering is shown to have a two-stage aggregation representation if these axioms and a separability assumption are satisfied. In the first stage, the distributions of each attribute are aggregated using generalized Gini social evaluation functions. The functional form of the second-stage aggregator depends on the number of attributes and on which version of a comonotonic additivity axiom is used. The implications of these results for the corresponding multidimensional indices of relative and absolute inequality are also considered.Generalized Gini; multidimensional inequality
Final spin of a coalescing black-hole binary: an Effective-One-Body approach
We update the analytical estimate of the final spin of a coalescing
black-hole binary derived within the Effective-One-Body (EOB) approach. We
consider unequal-mass non-spinning black-hole binaries. It is found that a more
complete account of relevant physical effects (higher post-Newtonian accuracy,
ringdown losses) allows the {\it analytical} EOB estimate to `converge towards'
the recently obtained {\it numerical} results within 2%. This agreement
illustrates the ability of the EOB approach to capture the essential physics of
coalescing black-hole binaries. Our analytical approach allows one to estimate
the final spin of the black hole formed by coalescing binaries in a mass range
() which is not presently covered by numerical
simulations.Comment: 8 pages, two figures. To appear in Phys. Rev.
Lyman Alpha and MgII as Probes of Galaxies and their Environments
Ly{\alpha} emission, Ly{\alpha} absorption and MgII absorption are powerful
tracers of neutral hydrogen. Hydrogen is the most abundant element in the
universe and plays a central role in galaxy formation via gas accretion and
outflows, as well as being the precursor to molecular clouds, the sites of star
formation. Since 21cm emission from neutral hydrogen can only be directly
observed in the local universe, we rely on Ly{\alpha} emission, and Ly{\alpha}
and MgII absorption to probe the physics that drives galaxy evolution at higher
redshifts. Furthermore, these tracers are sensitive to a range of hydrogen
densities that cover the interstellar medium, the circumgalactic medium and the
intergalactic medium, providing an invaluable means of studying gas physics in
regimes where it is poorly understood. At high redshift, Ly{\alpha} emission
line searches have discovered thousands of star-forming galaxies out to z = 7.
The large Ly{\alpha} scattering cross-section makes observations of this line
sensitive to even very diffuse gas outside of galaxies. Several thousand more
high-redshift galaxies are known from damped Ly{\alpha} absorption lines and
absorption by the MgII doublet in quasar and GRB spectra. MgII, in particular,
probes metal-enriched neutral gas inside galaxy haloes in a wide range of
environments and redshifts (0.1 < z < 6.3), including the so-called redshift
desert. Here we review what observations and theoretical models of Ly{\alpha}
emission, Ly{\alpha} and MgII absorption have told us about the interstellar,
circumgalactic and intergalactic medium in the context of galaxy formation and
evolution.Comment: 59 Pages, 19 Figures, 1 Table. Accepted for publication in
Publications of the Astronomical Society of the Pacifi
The mechanism regulating the dissociation of the centrosomal protein C-Nap1 from mitotic spindle poles
The centrosomal protein C-Nap1 is thought to play an important role in centrosome cohesion during interphase of the cell cycle. At the onset of mitosis, when centrosomes separate for bipolar spindle formation, C-Nap1 dissociates from centrosomes. Here we report the results of experiments aimed at determining whether the dissociation of C-Nap1 from mitotic centrosomes is triggered by proteolysis or phosphorylation. Specifically, we analyzed both the cell cycle regulation of endogenous C-Nap1 and the fate of exogenously expressed full-length C-Nap1. Western blot analyses suggested a reduction in the endogenous C-Nap1 level during M phase, but studies using proteasome inhibitors and destruction assays performed in Xenopus extracts argue against ubiquitin-dependent degradation of C-Nap1. Instead, our data indicate that the mitotic C-Nap1 signal is reduced as a consequence of M-phase-specific phosphorylation. Overexpression of full-length C-Nap1 in human U2OS cells caused the formation of large structures that embedded the centrosome and impaired its microtubule nucleation activity. Remarkably, however, these centrosome-associated structures did not interfere with cell division. Instead, centrosomes were found to separate from these structures at the onset of mitosis, indicating that a localized and cell-cycle-regulated activity can dissociate C-Nap1 from centrosomes. A prime candidate for this activity is the centrosomal protein kinase Nek2, as the formation of large C-Nap1 structures was substantially reduced upon co-expression of active Nek2. We conclude that the dissociation of C-Nap1 from mitotic centrosomes is regulated by localized phosphorylation rather than generalized proteolysis
War as a Collapse of Policy: A Critical Evaluation of Clausewitz
While there may be no single correct answer to the questions Clausewitz\u27s writings raise, it is essential that professional military men address themselves to the issues involved
Qualification Conditions for Calculus Rules of Coderivatives of Multivalued Mappings
AbstractThis paper establishes by a general approach a full calculus for the limiting Fréchet and the approximate coderivatives of multivalued mappings. This approach allows us to produce several new verifiable qualification conditions for such calculus rules
Transition from inspiral to plunge in precessing binaries of spinning black holes
We investigate the non-adiabatic dynamics of spinning black hole binaries by
using an analytical Hamiltonian completed with a radiation-reaction force,
containing spin couplings, which matches the known rates of energy and angular
momentum losses on quasi-circular orbits. We consider both a straightforward
post-Newtonian-expanded Hamiltonian (including spin-dependent terms), and a
version of the resummed post-Newtonian Hamiltonian defined by the Effective
One-Body approach. We focus on the influence of spin terms onto the dynamics
and waveforms. We evaluate the energy and angular momentum released during the
final stage of inspiral and plunge. For an equal-mass binary the energy
released between 40Hz and the frequency beyond which our analytical treatment
becomes unreliable is found to be, when using the more reliable Effective
One-Body dynamics: 0.6% M for anti-aligned maximally spinning black holes, 5% M
for aligned maximally spinning black hole, and 1.8% M for non-spinning
configurations. In confirmation of previous results, we find that, for all
binaries considered, the dimensionless rotation parameter J/E^2 is always
smaller than unity at the end of the inspiral, so that a Kerr black hole can
form right after the inspiral phase. By matching a quasi-normal mode ringdown
to the last reliable stages of the plunge, we construct complete waveforms
approximately describing the gravitational wave signal emitted by the entire
process of coalescence of precessing binaries of spinning black holes.Comment: 31 pages, 7 tables, and 13 figure
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