New Parametrizations for the Photon Structure Function

In the last year four new parametrizations of the Hadronic Photon Structure Function at Next to Leading Order have appeared. In this talk, I briefly review the main features of three of them: the FFNS_CJK, CJK and AFG.Comment: 7 pages, 2 figures. Talk presented at the Photon 2005 Conference, Warsaw (Poland

Art for Social Change: Supporting Art for Community Building, New Philanthropic Orientations in Egypt

Taking stock of recent developments in the field of philanthropy concerning the theme of Art for Social Change, this paper shall analyze the new cultural and artistic trends in civic participation and social engagement in Egypt that take their root well before the revolution and could be further emphasized following the Uprisings. The focus will be on new philanthropic orientations fostering community based cultural expressions rather than 'elitist' art forms or already recognized performing artists (concerts, opera, and blockbuster films)

Existence of financial equilibria with restricted participation

We consider a two-date model of a financial exchange economy with finitely many agents having nonordered preferences and portfolio constraints. There is a market for physical commodities at any state today or tomorrow and financial transfers across time and across states are allowed by means of finitely many nominal assets or numeraire assets. We prove a general existence result of equilibria for such a financial exchange economy in which portfolios are defined by linear constraints, extending the framework of linear equality constraints by Balasko et al. (1990) and the existence results in the unconstrained case by Cass (1984, 2006), Werner (1985), Duffie (1987) and Geanakoplos and Polemarchakis (1986). Our main result is a consequence of an auxiliary result, also of interest for itself, in which agents' portofolio constraints are defined by general closed convex sets and the financial structure is assumed to satisfy a "nonredundancy-type" assumption, weaker than the ones in Radner (1972) and Siconolfi (1989).Restricted participation; portfolio constraints; financial exchange economy; equilibrium; existence; arbitrage-free asset prices

Existence of financial equilibria with restricted participation

We consider a two-date model of a financial exchange economy with finitely many agents having nonordered preferences and portfolio constraints. There is a market for physical commodities at any state today or tomorrow and financial transfers across time and across states are allowed by means of finitely many nominal assets or num´eraire assets. We prove a general existence result of equilibria for such a financial exchange economy in which portfolios are defined by linear constraints, extending the framework of linear equality constraints by Balasko et al. (1990), and the existence results in the unconstrained case by Cass (1984, 2006), Werner (1985), Duffie (1987), and Geanakoplos and Polemarchakis (1986). Our main result is a consequence of an auxiliary result, also of interest for itself, in which agents’ portfolio constraints are defined by general closed convex sets and the financial structure is assumed to satisfy a ”nonredundancy-type” assumption, weaker than the ones in Radner (1972) and Siconolfi (1989).Restricted participation, portfolio constraints, financial exchange economy, equilibrium, existence, arbitrage-free asset prices

CJK-Improved 5 Flavour LO Parton Distributions in the Real Photon

Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real, unpolarized photon, improved in respect to our previous paper, are presented. We perform three global fits to the F_2^gamma data, using the LO DGLAP evolution equation. We improve the treatment of the strong coupling running and used lower values of Lambda_QCD, as we have found that the too high values adopted in the previous work caused the high chi^2 of the fits. In addition to the modified FFNS_CJKL model, referred to as FFNS_CJK 1 we analyse a FFNS_CJK 2 model in which we take into account the resolved-photon heavy-quark contribution. New CJK model with an improved high-x behavior of the F_2^gamma(x,Q^2) is proposed. Finally, in the case of the CJK model we abandon the valence sum rule imposed on the VMD input densities. New fits give chi^2 per degree of freedom about 0.25 better than the old results. All features of the CJKL model, such as the realistic heavy-quark distributions, good description of the LEP data on the Q^2 dependence of the F_2^gamma and on F_2,c^gamma are preserved. Moreover we present results of an analysis of the uncertainties of the CJK parton distributions due to the experimental errors. It is based on the Hessian method used for the proton and very recently applied for the photon by one of us. Parton and structure function parametrizations of the best fits in both FFNS_CJK and CJK approaches are made accessible. For the CJK model we provide also sets of test parametrizations which allow for calculation of uncertainties of any physical value depending on the real photon parton densities.Comment: 27 pages, 14 figures, FORTRAN programs available at http://www.fuw.edu.pl/~pjank/param.htm

Arbitrage and Equilibrium with Portfolio Constraints

We consider a multiperiod financial exchange economy with nominal assets and restricted participation, where each agent’s portfolio choice is restricted to a closed, convex set containing zero, as in Siconolfi (1989). Using an approach that dates back to Cass (1984, 2006) in the unconstrained case, we seek to isolate arbitrage-free asset prices that are also quasi-equilibrium or equilibrium asset prices. In the presence of such portfolio restrictions, we need to confine our attention to aggregate arbitrage-free asset prices, i.e., for which there is no arbitrage in the space of marketed portfolios. Our main result states that such asset prices are quasi-equilibrium prices under standard assumptions and then deduce that they are equilibrium prices under a suitable condition on the accessibility of payoffs by agents, i.e., every payoff that is attainable in the aggregate can be marketed through some agent’s portfolio set. This latter result extends previous work by Martins-da-Rocha and Triki (2005).Stochastic Financial exchange economies; Incomplete markets; Financial equilibrium; Constrained portfolios; Multiperiod models; Arbitrage-free asset prices

The location of R&D in the Netherlands: trends, determinants and policy

Many factors determine the location of business R&D projects, the most important being history, the supply of R&D labour, and the quality of the public knowledge infrastructure (including the science-industry knowledge transfer). The set of R&D locations in the Netherlands changes little over time. But two things do change regularly: the size of the R&D activities at a particular site and the name and nationality of the owner of an R&D site. The Netherlands takes an average or higher position in a ranking of OECD countries according to attractiveness to the location of business R&D. Since domestic R&D is an important engine for domestic economic growth and since the market fails to provide optimal incentives for R&D, there is scope for government policy that improves upon the R&D location climate. Yet, this policy rationale does not necessarily imply that R&D policy initiatives are always effective and efficient: elasticities and social (opportunity) costs should be taken into account.

Large rescaling of the scalar condensate, towards a Higgs-gravity connection ?

In the Standard Model the Fermi constant is associated with the vacuum expectation value of the Higgs field $$, `the condensate', usually believed to be a nearly cut-off independent quantity. General arguments related to the `triviality' of $\lambda\Phi^4$ theory in 4 space-time dimensions suggest, however, a dramatic renormalization effect in the continuum theory. This effect is visible on the relatively large lattices (such as $32^4$) available today. The result is suggestive of a certain `Higgs-gravity connection', as discussed some years ago. The space-time structure is determined by symmetry breaking and the Planck scale is essentially a rescaling of the Fermi scale. The resulting picture may lead to quite substantial changes in the usual phenomenology associated with the Higgs particle.Comment: 6 page

Existence of Equilibria with a Tight Marginal Pricing Rule.

This paper deals with the existence of marginal pricing equilibria when it is defined by using a new and tighter normal cone introducedby B. Cornet and M.O. Czarnecki. The main interest of this new definition of the marginal pricing rule comes from the fact that it is more precise in the sense that the set of prices satisfying the condition is smaller than the one given by the Clarke's normal cone. The counter- part is that it is not convex valued, which leads to some mathematical diffculties in the existence proof. The result is obtained through an approximation argument under the same assumptions as in the previous existence results.General economic equilibrium, increasing returns, marginal pricing rule, existence.

Elimination of Arbitrage States in Asymmetric Information Models

In a financial economy with asymmetric information and incomplete markets, we study how agents, having no model of how equilibrium prices are determined, may still refine their information by eliminating sequentially "arbitrage state(s)", namely, the state(s) which would grant the agent an arbitrage, if realizable.Arbitrage, Incomplete markets, Asymmetric information, Information revealed by prices