Matrix Element and Strong Electron Correlation Effects in ARPES from Cuprates

We discuss selected results from our recent work concerning the ARPES (angle-resolved photoemission) spectra from the cuprates. Our focus is on developing an understanding of the effects of the ARPES matrix element and those of strong electron correlations in analyzing photointensities. With simulations on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212), we show that the ARPES matrix element possesses remarkable selectivity properties, such that by tuning the photon energy and polarization, emission from the bonding or the antibonding states can be enhanced. Moreover, at low photon energies (below 25 eV), the Fermi surface (FS) emission is dominated by transitions from just the O-atoms in the CuO$_2$ planes. In connection with strong correlation effects, we consider the evolution with doping of the FS of Nd$_{2-x}$Ce$_x$CuO$_{4\pm\delta}$ (NCCO) in terms of the $t$-$t'$-$U$ Hubbard model Hamiltonian. We thus delineate how the FS evolves on electron doping from the insulating state in NCCO. The Mott pseudogap is found to collapse around optimal doping suggesting the existence of an associated quantum critical point.Comment: 5 pages, 4 figures, accepted to be published in Journal of Physics and Chemistry of Solid

Beta-Beams: present design and expected performances

We give the present status of the beta-beam study, which aims at producing intense nue and antinue beams from the decay of relativistic radioactive io ns. The emphasis is put on recent technical progress and new ideas. The expected performances in terms of neutrino mixing parameters theta13 and CP violating phase delta using a megaton water Cerenkov detector installed in the Frejus underground laboratory are shown to be excellent, and the synergy with a a companion SuperBeam is underlined.Comment: Contributed paper at Nufact 03, New York, US

Sharing Rules and Stability in Coalition Games with Externalities

This paper examines cooperative sharing rules in fisheries coalition games and develops a new sharing rule that takes into account the stability of cooperation when externalities are present. We contribute to existing knowledge by introducing a connection between cooperative games (sharing rules) and non-cooperative games (stability). As an illustrative example, we describe a discrete-time, deterministic, coalition game model of the major agents who exploit the cod stock in the Baltic Sea.Baltic Sea cod, characteristic function, coalition game, cooperation, fisheries, nucleolus, Shapley value, sharing rules, stability of cooperation, Environmental Economics and Policy, C62, C70, Q22, Q28,

On Species Preservation and Non-Cooperative Exploiters

Game-theoretic fisheries models typically consider cases where some players harvest a single common fish stock. It is, however, the case that these types of models do not capture many real world mixed fisheries, where species are bio-logical independent or dependent. The present paper considers cases where several non-cooperative exploiters are involved in mixed fisheries. This paper is targeting biodiversity preservation by setting up a two species model with the aim of ensuring both species survive harvesting of exploiters adapting a non-cooperative behaviour. The model starts out as a multi-species model without biological dependency and is then modified to include also biological dependency. We contribute to the literature by analytically finding the limits on the number of players preserving both species including the conditions to be satisfied. For visual purposes we simulate a two species model with different kind of interrelationship.Biodiversity preservation, non-cooperative game, multi-species fisheries, bio-economic modelling

Centralised versus Decentralised Enforcement of Fish Quotas

The purpose of this article is to consider under what circumstances it is better to have centralised enforcement of catch quotas and when it is better to leave enforcement to the countries themselves. It is shown for a two-country case that a welfare gain is obtained under centralised enforcement at the federal level. The result depends critically on the difference in the unit cost of enforcement at the federal and the Member State (regional) level. If the Member States have a sufficiently large cost advantage in enforcing quotas, they can be better off under decentralised enforcement. In addition, the result depends on the proportion of foreign fishermen in the domestic fishing zone. The higher the proportion of foreign fishermen in the domestic zone, the better the decentralised enforcement of quotas.Quota enforcement policy, fisheries management, Industrial Organization, International Relations/Trade, Political Economy, Q22, Q28.,

On the absence of appreciable half-life changes in alpha emitters cooled in metals to 1 Kelvin and below

The recent suggestion that dramatic changes may occur in the lifetime of alpha and beta decay when the activity, in a pure metal host, is cooled to a few Kelvin, is examined in the light of published low temperature nuclear orientation (LTNO) experiments, with emphasis here on alpha decay. In LTNO observations are made of the anisotropy of radioactive emissions with respect to an axis of orientation. Correction of data for decay of metallic samples held at temperatures at and below 1 Kelvin for periods of days and longer has been a routine element of LTNO experiments for many years. No evidence for any change of half life on cooling, with an upper level of less than 1%, has been found, in striking contrast to the predicted changes, for alpha decay, of several orders of magnitude. The proposal that such dramatic changes might alleviate problems of disposal of long-lived radioactive waste is shown to be unrealistic.Comment: 27 pages, 12 figures, accepted for publication in Nucl.Phys.A. Revised version, including quantitative analysis of the sensitivity of nuclear orientation experiments, discussed in this work, to changes of alpha-decay lifetimes in metals at low temperatures. Conclusions remain unchange