29,088 research outputs found
Integrable Quasiclassical Deformations of Algebraic Curves
A general scheme for determining and studying integrable deformations of
algebraic curves is presented. The method is illustrated with the analysis of
the hyperelliptic case. An associated multi-Hamiltonian hierarchy of systems of
hydrodynamic type is characterized.Comment: 28 pages, no figure
Nonlinear Dynamics on the Plane and Integrable Hierarchies of Infinitesimal Deformations
A class of nonlinear problems on the plane, described by nonlinear
inhomogeneous -equations, is considered. It is shown that the
corresponding dynamics, generated by deformations of inhomogeneous terms
(sources) is described by Hamilton-Jacobi type equations associated with
hierarchies of dispersionless integrable systems. These hierarchies are
constructed by applying the quasiclassical -dressing method.Comment: 30 pages, tcilate
Hydrodynamic reductions and solutions of a universal hierarchy
The diagonal hydrodynamic reductions of a hierarchy of integrable
hydrodynamic chains are explicitly characterized. Their compatibility with
previously introduced reductions of differential type is analyzed and their
associated class of hodograph solutions is discussed.Comment: 19 page
dbar-approach to the dispersionless KP hierarchy
The dispersionless limit of the scalar nonlocal dbar-problem is derived. It
is given by a special class of nonlinear first-order equations. A
quasi-classical version of the dbar-dressing method is presented. It is shown
that the algebraic formulation of dispersionless hierarchies can be expressed
in terms of properties of Beltrami tupe equations. The universal Whitham
hierarchy and, in particular, the dispersionless KP hierarchy turn out to be
rings of symmetries for the quasi-classical dbar-problem.Comment: 13 pages, LaTex 24.9K
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The relationship of drug reimbursement with the price and the quality of pharmaceutical innovations
This paper studies the strategic interaction between pharmaceutical firms' pricing decisions and government agencies' reimbursement decisions which discriminate between patients by giving reimbursement rights to patients for whom the drug is most effective. We show that if the reimbursement decision preceeds the pricing decision, the agency only reimburses some patients if the private and public health benefits from the new drug diverge. That is, when (i) there are large externalities of consuming the drug and (ii) the difference in costs between the new drug and the alternative treatment is large. Alternatively, if the firm can commit to a price in advance of the reimbursement decision, we identify a strategic effect which implies that by committing to a high price ex ante, the firm can force a listing outcome and make the agency more willing to reimburse than in the absence of commitment
On the Potential of Leptonic Minimal Flavour Violation
Minimal Flavour Violation can be realized in several ways in the lepton
sector due to the possibility of Majorana neutrino mass terms. We derive the
scalar potential for the fields whose background values are the Yukawa
couplings, for the simplest See-Saw model with just two right-handed neutrinos,
and explore its minima. The Majorana character plays a distinctive role: the
minimum of the potential allows for large mixing angles -in contrast to the
simplest quark case- and predicts a maximal Majorana phase. This points in turn
to a strong correlation between neutrino mass hierarchy and mixing pattern.Comment: 6 pages; version published on Physics Letters
Effects of galaxy interactions in different environments
We analyse star formation rates derived from photometric and spectroscopic
data of galaxies in pairs in different environments using the 2dF Galaxy
Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey (SDSS). The two
samples comprise several thousand pairs, suitable to explore into detail the
dependence of star formation activity in pairs on orbital parameters and global
environment. We use the projected galaxy density derived from the fifth nearest
neighbour of each galaxy, with convenient luminosity thresholds to characterise
environment in both surveys in a consistent way. Star formation activity is
derived through the parameter in 2dFGRS and through the star formation
rate normalised to the total mass in stars, , given by Brinchmann et
al. (2004) in the second data release SDSS-DR2. For both galaxy pair catalogs,
the star formation birth rate parameter is a strong function of the global
environment and orbital parameters. Our analysis on SDSS pairs confirms
previous results found with the 2dFGRS where suitable thresholds for the star
formation activity induced by interactions are estimated at a projected
distance r_{\rm p} = 100 \kpc and a relative velocity km
. We observe that galaxy interactions are more effective at triggering
important star formation activity in low and moderate density environments with
respect to the control sample of galaxies without a close companion. Although
close pairs have a larger fraction of actively star-forming galaxies, they also
exhibit a greater fraction of red galaxies with respect to those systems
without a close companion, an effect that may indicate that dust stirred up
during encounters could be affecting colours and, partially, obscuring
tidally-induced star formation.Comment: accepted MNRA
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