Lagging behind versus advancing too fast? identifying gaps research in supply chain

The objective of our work is to analyze the evolution and actual trends of research in Supply Chain Management (SCM). We pretend to show how the different topics have been methodologically studied, and to determine how the advent of the so-called 'New Economy' has influenced SCM research. To get this objective, we carry out a literature review of twelve refereed journals in the Operations Management (OM) area for the period 1995-2001. Statistical tools are used to analyze the obtained information

The transition out of education and the initial steps into the labour market in the European Union

The general aim of this research is the study of transitions from education and into the labour market among youths under a simultaneous framework in order to control for the interdependency of such relevant events. An extended version of the human capital model has been applied using the European Community Household Panel. The empirical strategy has aimed at reflecting the independent and simultaneous determination of both labour market and education transitions. Results show that the expected labour market outcomes do not significantly contribute to explain demand for education, other factors being more important. Finally, in the school-to-work transition, demand-side and institutional factors turn to be very important, education attainment effects being blurred by the nature of our sample (students in different points of their programmes).youth labour market ; human capital ; labour supply ; simultaneous decisions

Gas Chromatography-Mass Spectrometry Study of the Essential Oils of Schinus longifolia (Lindl.) Speg., Schinus fasciculata (Griseb.) I. M. Johnst., and Schinus areira L.

The essential oil composition from the aerial parts of three Anacardiaceae growing in Bah¨ªa Blanca, Argentina was studied by gas chromatography and gas chromatography-mass spectrometry. The essential oils of S. longifolia and S. fasciculata have been studied for the first time. The major constituents were ¦Á-pinene (46.5%), ¦Â-pinene (15.1%) and ¦Á-phellandrene (10.1%) for S. longifolia and limonene (10.9%), ¦Â-phellandrene (6.16%) and ¦Á-phellandrene (5.6%) for S. fasciculata. The major components of the essential oil of S. areira were limonene (28.6%), ¦Á-phellandrene (10.1%), sabinene (9.2%) and camphene (9.2%) differing from the literature data. The essential oils from S. areira and S. longifolia exhibited a high biotoxicity in a brine shrimp assay with Artemia persimilis.Fil: Murray, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Frontera, Maria Eugenia. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Tomas, María A.. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; ArgentinaFil: Mulet, María Cristina. Universidad Nacional del Sur. Departamento de Química. Instituto de Investigaciones en Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Polyhedral geometry of Phylogenetic Rogue Taxa

It is well known among phylogeneticists that adding an extra taxon (e.g. species) to a data set can alter the structure of the optimal phylogenetic tree in surprising ways. However, little is known about this "rogue taxon" effect. In this paper we characterize the behavior of balanced minimum evolution (BME) phylogenetics on data sets of this type using tools from polyhedral geometry. First we show that for any distance matrix there exist distances to a "rogue taxon" such that the BME-optimal tree for the data set with the new taxon does not contain any nontrivial splits (bipartitions) of the optimal tree for the original data. Second, we prove a theorem which restricts the topology of BME-optimal trees for data sets of this type, thus showing that a rogue taxon cannot have an arbitrary effect on the optimal tree. Third, we construct polyhedral cones computationally which give complete answers for BME rogue taxon behavior when our original data fits a tree on four, five, and six taxa. We use these cones to derive sufficient conditions for rogue taxon behavior for four taxa, and to understand the frequency of the rogue taxon effect via simulation.Comment: In this version, we add quartet distances and fix Table 4

Revisiting the two-mass model of the vocal folds

Realistic mathematical modeling of voice production has been recently boosted by applications to different fields like bioprosthetics, quality speech synthesis and pathological diagnosis. In this work, we revisit a two-mass model of the vocal folds that includes accurate fluid mechanics for the air passage through the folds and nonlinear properties of the tissue. We present the bifurcation diagram for such a system, focusing on the dynamical properties of two regimes of interest: the onset of oscillations and the normal phonation regime. We also show theoretical support to the nonlinear nature of the elastic properties of the folds tissue by comparing theoretical isofrequency curves with reported experimental data.Comment: 7 pages, 5 figure

A cosmological model for corrugated graphene sheets

Defects play a key role in the electronic structure of graphene layers flat or curved. Topological defects in which an hexagon is replaced by an n-sided polygon generate long range interactions that make them different from vacancies or other potential defects. In this work we review previous models for topological defects in graphene. A formalism is proposed to study the electronic and transport properties of graphene sheets with corrugations as the one recently synthesized. The formalism is based on coupling the Dirac equation that models the low energy electronic excitations of clean flat graphene samples to a curved space. A cosmic string analogy allows to treat an arbitrary number of topological defects located at arbitrary positions on the graphene plane. The usual defects that will always be present in any graphene sample as pentagon-heptagon pairs and Stone-Wales defects are studied as an example. The local density of states around the defects acquires characteristic modulations that could be observed in scanning tunnel and transmission electron microscopy.Comment: Proceedings of the Graphene Conference, MPI PKS Dresden, September 200