Linear semigroups with coarsely dense orbits

Let $S$ be a finitely generated abelian semigroup of invertible linear operators on a finite dimensional real or complex vector space $V$. We show that every coarsely dense orbit of $S$ is actually dense in $V$. More generally, if the orbit contains a coarsely dense subset of some open cone $C$ in $V$ then the closure of the orbit contains the closure of $C$. In the complex case the orbit is then actually dense in $V$. For the real case we give precise information about the possible cases for the closure of the orbit.Comment: We added comments and remarks at various places. 14 page

Les opérations de restructuration des firmes agroalimentaires multinationales entre 1987 et 2003

Based on a neo-institutionalist theoretical framework and using the Agrodata databank, the present paper analyses the main drivers underlying the restructuring operations of the top 100 multinational food processing enterprises worldwide and draws the map of the world's new agri-food landscape. World's agri-food oligopoly came out during these last decades concentrating an ever increasing financial and economic power (in 2002, the total value production of the top 100 food multinationals weighted for 27 % of the total production of the world food processing industry). Under constant pressure to improve their financial and economic performances, food processing enterprises face considerable constraints inherent in their international business environment : increasing international rivalry resulting from the adoption of liberalising economic policies by a large number of developing countries; importance that gain the financial spheres in world's agri-food chain; changing eating habits and consumer behaviour. Leadership seeking on large regional and/or world base in highly segmented markets pushes the top 100 food multinationals to reorganise their internal and external structures by adopting streamlining and cost cutting strategies while targeting larger geographical expansion thanks to mergers and acquisitions as well as partnerships that they realise. Consequently, they reshape world's agri-food lanscape and give way to the emergence of new finance-oriented governance patterns. ...French Abstract : En mobilisant une grille de lecture néo-institutionnaliste et en s'appuyant sur la base de données Agrodata, ce document analyse les logiques qui sous-tendent les restructurations des 100 premières firmes multinationales agroalimentaires mondiales et la nouvelle carte du monde agroalimentaire qui en résulte. On montre ainsi qu'un oligopole agroalimentaire de dimension internationale s'est progressivement constitué et que son poids économique et financier ne cesse de croître (les 100 premiers groupes mondiaux représentaient en 2002 près de 27% du chiffre d'affaires du secteur). L'intensification de la concurrence impulsée par l'ouverture des marchés, la financiarisation du secteur et les changements dans les comportements des consommateurs ont imposé aux entreprises de nouveaux impératifs de performance. La recherche du leadership macro-régional, voire mondial, sur des marchés de plus en plus segmentés conduit cet oligopole à mener des opérations de restructuration visant la rationalisation des coûts tout en soutenant une croissance externe (acquisitions, fusions, cessions, partenariats). Le profil du secteur au niveau mondial s'en trouve reconfiguré et l'on assiste à l'apparition de nouveaux types de gouvernance, plus financiarisés.MULTINATIONAL ENTERPRISES; STRATEGY; RESTRUCTURING; ECONOMIC PERFORMANCES; AGRI-FOOD MARKETS

Vulnerabilty of euro-mediterranean regions producing fresh and processed fruits & vegetables, in a context of international liberalization = Vulnérabilité des régions euroméditerranéennes productrices de fruits & légumes frais et transformés, dans un contexte de libéralisation internationale

This paper dealts with the economic impact of agricultural trade liberalization on the fruit and vegetable marketing chains of five EU mediterranean countries. The theoretical tools of this research are based on industrial organization (Scherer, 1973), strategic analysis (Wernerfelt, 1983) and global commodity chain concept (Gereffi, 1995). A "regional vulnerability index" (RVI) is built through an inter-regional benchmarking. The RVI itself is calculated from a range of indicators taking into account the following aspects: concentration and production specialization, differents forms of organization and public incentives, average period dynamics, economic and firm performances, sector-based and macroeconomic environmental constraints. An impact simulation, combining RVI and penetration of european markets, suggests a reasonable competition with regard to the commercial risk: 4% of the present production acounting to 2 billion (i.e. 30 000 specialized farms and 80 000 corresponding jobs located within fifty regions) are threatened. ...French Abstract : Ce document propose une estimation de l'impact économique de la libéralisation des échanges commerciaux euro-méditerranéens sur les filières fruits et légumes dans 5 pays méditerranéens de l'Union européenne. Les fondements théoriques de la recherche sont empruntés à l'organisation industrielle (Scherer, 1973), à l'analyse stratégique (notamment Wernerfelt, 1983) et au concept de chaîne globale de valeur (Gereffi, 1995). Un " indice de vulnérabilité régionale " (IVR) est mobilisé pour un benchmarking inter-régional. L'IVR est calculé à partir d'une batterie d'indicateurs quantitatifs et qualitatifs prenant en compte les aspects suivants : concentration et spécialisation de l'offre, formes d'organisation et incitations publiques, dynamiques de moyenne période, de performances économiques et managériales, facteurs d'environnement sectoriel et macro-économique. Une simulation d'impact, combinant IVR et pénétration du marché européen, suggère une exposition modérée au risque commercial, menaçant 4 % de la production actuelle (soit 2 milliards), 30 000 exploitations agricoles spécialisées et 80 000 emplois dans une cinquantaine de régions européennes.AGRICULTURAL TRADE LIBERALIZATION; FRUIT AND VEGETABLE MARKETING CHAINS; INDUSTRIAL ORGANIZATION; STRATEGIC ANALYSIS; GLOBAL COMMODITY CHAIN; ;MEDITERRANEAN COUNTRIES

Trigonometric Sutherland systems and their Ruijsenaars duals from symplectic reduction

Besides its usual interpretation as a system of $n$ indistinguishable particles moving on the circle, the trigonometric Sutherland system can be viewed alternatively as a system of distinguishable particles on the circle or on the line, and these 3 physically distinct systems are in duality with corresponding variants of the rational Ruijsenaars-Schneider system. We explain that the 3 duality relations, first obtained by Ruijsenaars in 1995, arise naturally from the Kazhdan-Kostant-Sternberg symplectic reductions of the cotangent bundles of the group U(n) and its covering groups $U(1) \times SU(n)$ and ${\mathbb R}\times SU(n)$, respectively. This geometric interpretation enhances our understanding of the duality relations and simplifies Ruijsenaars' original direct arguments that led to their discovery.Comment: 34 pages, minor additions and corrections of typos in v

Pyrene bisiminopyridine ligand and its zinc complex

The synthesis of a pyrene bisiminopyridine ligand L was successfully accomplished by condensation between 1-aminopyrene and 2,6-pyridinecarboxaldehyde. The complexation of L with zinc triflate afforded a neutral metal complex formulated as [Zn(H2O)LCF3SO3)2].2Et2O. In the complex, the ligand is coordinated to zinc(II) through its three nitrogen atoms which form a distorted octahedral environment together with three oxygen atoms, two from the triflate anions and one from aqua ligand. Both compounds have been characterized using NMR, elemental analysis, mass spectrometry, electronic absorption (UV-Vis) and infrared. Luminescence properties of these compounds show an emission maxima at 412 nm, indicating a pyrene monomer emission

Decay resistance against Coriolus versicolor in Sessile oak ( Quercus petraea Liebl.): analysis of the between-tree variability and correlations with extractives, tree growth and other basic wood properties

Abstract : Weight loss due to fungus Coriolus versicolor has been measured on 614 samples according to the NF EN 113 norm. Up to eight samples were cut at breast height (two opposite radii×four radial positions in heartwood) from 82 mature sessile oaks ( Quercus petraea Liebl.) originating from contrasting regions, silvicultural schedules and site qualities in France. The following points are addressed in the paper: (i) contribution to the total variability for weight loss of the effects "tree”, "position in the tree”, as well as their interaction; (ii) percentage of wood samples and trees in each of the five classes of natural durability defined by the norm NF EN 350-2; (iii) test of the effects of region, silvicultural schedule and site quality on weight loss and evaluating their contribution to the total variation; and (iv) correlations at tree level between weight loss and several traits related to tree growth and basic wood properties (density, swelling, grain angle, multiseriate wood rays characteristics, extractives content). The results are discussed with a view to aid the forest manager as well as the log/wood user to take advantage of the high level of between-tree variability observed as natural durability against C. versicolo

An integrable BC(n) Sutherland model with two types of particles

A hyperbolic BC(n) Sutherland model involving three independent coupling constants that characterize the interactions of two types of particles moving on the half-line is derived by Hamiltonian reduction of the free geodesic motion on the group SU(n,n). The symmetry group underlying the reduction is provided by the direct product of the fixed point subgroups of two commuting involutions of SU(n,n). The derivation implies the integrability of the model and yields a simple algorithm for constructing its solutions.Comment: 14 pages, with minor modifications in v