An optimal matching problem

Given two measured spaces (X,dx), (Y,dy) and a third space Z, given two functions u(x,z) and v(x,z), we study the problem of finding two maps s from X to Z and t from Y to Z such that the images s(dx) and t(dy) coincide, and the integral of u(x,s(x))dx+v(y,t(y))dy is maximal. We give condition on u and v for which there is a unique solution

Gluons, quarks and deconfinement at high density

We compute gluon and quark propagators in 2-colour QCD at large baryon chemical potential mu. The gluon propagator is found to be antiscreened in the superfluid, confined phase and screened in the large-mu, deconfined phase. We present the first attempt to determine corresponding electric and magnetic gluon masses. The quark propagator undergoes dramatic modifications in the superfluid region as a result of the formation of a superfluid gap. These modifications include the appearance of zero crossings in the vector part of the (normal) quark propagator, a large suppression of the scalar part, and the emergence of anomalous propagation.Comment: 11 pp, 9 figures; talk presented at QCD-TNT, Trento, 7-11 sep 200

Agriculture versus fish – Norway in WTO

The Norwegian agriculture is highly protected and subsidised. The opposite is the case for fisheries and fish farming which suffer from foreign market restrictions. Using a computational general equilibrium model, the gain for Norway of a complete elimination of food subsidies and tariffs is estimated to be in the range of 1.2 - 2.7 per cent of GDP. Most of this gain stems from domestic farm sector iberalisation. The gain from free market access for seafood is estimated to 4.4 per cent of the seafood export value. Consequently, Norway has much to gain from offering other countries market access for agricultural products. In return, Norway should demand free access for their fish products.general equilibrium model; cost of agricultural policy; trade liberalisation; food industry; fisheries.

A surjection theorem for maps with singular perturbation and loss of derivatives

In this paper we introduce a new algorithm for solving perturbed nonlinear functional equations which admit a right-invertible linearization, but with an inverse that loses derivatives and may blow up when the perturbation parameter $\epsilon$ goes to zero. These equations are of the form $F\_\epsilon(u)=v$ with $F\_\epsilon(0)=0$, $v$ small and given, $u$ small and unknown. The main difference with the by now classical Nash-Moser algorithm is that, instead of using a regularized Newton scheme, we solve a sequence of Galerkin problems thanks to a topological argument. As a consequence, in our estimates there are no quadratic terms. For problems without perturbation parameter, our results require weaker regularity assumptions on $F$ and $v$ than earlier ones, such as those of Hormander. For singularly perturbed functionals, we allow $v$ to be larger than in previous works. To illustrate this, we apply our method to a nonlinear Schrodinger Cauchy problem with concentrated initial data studied by Texier-Zumbrun, and we show that our result improves significantly on theirs.Comment: Final version, to appear in Journal of the European Mathematical Society (JEMS

Can a Warmer Climate Save Northern Agriculture?

Agriculture at high latitudes is expected to be a main beneficiary of a man-made climate change. A numerical model, using Norway as a case, is employed to analyze the impacts of a warmer climate on northern agriculture. The computations indicate that the current degree of self-sufficiency can be achieved with less budget support and higher economic welfare. However, it may be argued that environmental goods, such as landscape and biodiversity preservation, and rural settlement, are more important than self-sufficiency for northern agriculture. It is demonstrated that, in that case, welfare gains are substantially lower, and can even be negative.climate change, northern agriculture, environmental goods, numerical model, Environmental Economics and Policy, Resource /Energy Economics and Policy, L52, Q18, Q24,

What constitutes a convention? Implications for the coexistence of conventions

A model of repeated play of a coordination game, where stage games have a location in social space, and players receive noisy signals of the true location of their games, is reviewed. Sugden (1995) suggests that in such a model, there can be a stationary state of convention coexistence only if interaction is non-uniform across social space. This paper shows that an alternative definition of conventions, which links conventions to actions rather than expectations, permits convention coexistence when interaction is uniform. To assess robustness, the concept of a global mutant is introduced, to which certain states of coexistence are robust.Conventions Coordination game Equilibrium selection JEL classification: C73

Parental Income and Risk Behaviour as Determinants of Adolescent Health

The relationship between health and income among adults is well established. Adolescent health and parental income has not received the same attention. In this study we look at household income both as a direct determinant of adolescent health and as an important factor in relation to behavioural patterns among adolescents. The data used is from two surveys conducted in a Norwegian county (n=9 000, which accounts for 90 % of the age-group 13-19 in a Norwegian county). The results indicate that income works partly through some health-promoting behaviours but, still has a significant direct effect on adolescent health. We also find that high household-income does not cushion the effect of health-deteriorating behaviour, but it strengthens the probability that adolescents take part in physical activity. Household income is important in terms of increasing the probability that adolescents actively participate in sports and physical activity in general.