A germination study of herbicide-resistant field poppies in Spain

Field poppy, Papaver rhoeas L., is a very common weed in winter cereals in North-Eastern Spain. Its control is becoming difficult due to expanding herbicide resistance. To control field poppies there are alternative strategies such as non-chemical control that take into account the weed emergence period. However, there is a lack of knowledge of P. rhoeas emergence patterns in semi-arid conditions. Thus, here we conducted pot experiments on the emergence of P. rhoeas. We aimed to describe the emergence period and to quantify the emergence of a susceptible and of a herbicide-resistant P. rhoeas population at two locations in Catalonia, Spain, from 1998 to 2001 and until 2004 at one of them. Therefore, pots containing seeds of both populations were established at the two locations and emergence was recorded monthly. We studied the origin of the population, the sowing location, the effect of cultivation and the sowing year. First, we found that the main emergence peaks in our experiments occurred in autumn, accounting for between 65.7 and 98.5% of the annual emergence from October to December, and only little emergence was recorded in spring. This emergence pattern is different from those found in the literature corresponding to Northern European countries, where in some cases main flushes occur only in autumn, in spring and winter or only in spring. The emergence was mainly affected by cultivation, but the effect of light stimulus was observed several months later. As a consequence, cultivation should be done in early autumn, promoting emergence during the whole autumn and winter so that emerged seedlings can be controlled before sowing a spring crop. Second, most experiments showed that the emergence was significantly higher in the first autumn than in the following seasons, e.g. 4.1% emergence in the first year and only 2.1, 2.3, 0.5 and 0.6% new emergence at one of the locations for the second, third, fourth and fifth years. Thus, after having a severe P. rhoeas infestation causing a big seed rain, emergence should be stimulated by autumn cultivation in the following season and seedlings controlled by trying to deplete the soil seed bank as much as possible. Despite the fact that emergence will be staggered throughout several years and that there was a significant relationship between rainfall and emergence, so that dry years will cause a smaller emergence rate of the weed, these findings define a cultural management strategy to reduce P. rhoeas infestations and to contribute to integrated weed management strategies combining it with other tools.

Deliberative ecological economics: emergence and research issues

We discuss the recent emergence of "deliberative ecological economics", a field that highlights the potential of deliberation for improving environmental governance. We locate the emergence of this literature in the long concern in ecological economics over the policy implications of limited views of human action and its encounter with deliberative democracy scholarship and the model of communicative rationality as an alternative to utilitarianism. Considering criticisms over methods used and the focus of research in deliberative decision-making, we put forward a research agenda for deliberative ecological economics. Given the promising potential of deliberative processes for improving the effectiveness and legitimacy of environmental decision-making, work in this area could help advance both theory and practice in environmental governance.

Fréedericksz transition in a periodic magnetic field

We study the Fréedericksz transition in a twist geometry under the effect of a periodic modulation of the magnitude of the applied magnetic field. We find a shift of the effective instability point and a time-periodic state with anomalously large orientational fluctuations. This time-periodic state occurs below threshold and it is accompanied by a dynamically stabilized spatial pattern. Beyond the instability the emergence of a transient pattern can be significantly delayed by a fast modulation, allowing the observation of pattern selection by slowing down the reorientational dynamics.

Empiricism in ecological economics: a perspective from complex systems theory

Economies are open complex adaptive systems far from thermodynamic equilibrium, and neo-classical environmental economics seems not to be the best way to describe the behaviour of such systems. Standard econometric analysis (i.e. time series) takes a deterministic and predictive approach, which encourages the search for predictive policy to ‘correct’ environmental problems. Rather, it seems that, because of the characteristics of economic systems, an ex-post analysis is more appropriate, which describes the emergence of such systems’ properties, and which sees policy as a social steering mechanism. With this background, some of the recent empirical work published in the field of ecological economics that follows the approach defended here is presented. Finally, the conclusion is reached that a predictive use of econometrics (i.e. time series analysis) in ecological economics should be limited to cases in which uncertainty decreases, which is not the normal situation when analysing the evolution of economic systems. However, that does not mean we should not use empirical analysis. On the contrary, this is to be encouraged, but from a structural and ex-post point of view.

Europeanization and the Emergence of a European Society

This article examines the European integration process from a sociological perspective, where the main focus is the examination of the social consequences of the integration process. The European Union has advanced significantly in the economic, social, and political integration processes. This has resulted in a rapid Europeanization of behavior. There has hardly been any progress, however, toward the development of European social groups. This article examines the causes of this lag and concludes that it is highly unlikely that in the middle run there be significant progress toward the Europeanization of society.

Simulations of parasitic and intrinsic capacitances related to Multiple-Gate-Field-Effect Transistor architectures

Report for the scientific sojourn carried out at the Université Catholique de Louvain, Belgium, from March until June 2007. In the first part, the impact of important geometrical parameters such as source and drain thickness, fin spacing, spacer width, etc. on the parasitic fringing capacitance component of multiple-gate field-effect transistors (MuGFET) is deeply analyzed using finite element simulations. Several architectures such as single gate, FinFETs (double gate), triple-gate represented by Pi-gate MOSFETs are simulated and compared in terms of channel and fringing capacitances for the same occupied die area. Simulations highlight the great impact of diminishing the spacing between fins for MuGFETs and the trade-off between the reduction of parasitic source and drain resistances and the increase of fringing capacitances when Selective Epitaxial Growth (SEG) technology is introduced. The impact of these technological solutions on the transistor cut-off frequencies is also discussed. The second part deals with the study of the effect of the volume inversion (VI) on the capacitances of undoped Double-Gate (DG) MOSFETs. For that purpose, we present simulation results for the capacitances of undoped DG MOSFETs using an explicit and analytical compact model. It monstrates that the transition from volume inversion regime to dual gate behaviour is well simulated. The model shows an accurate dependence on the silicon layer thickness,consistent withtwo dimensional numerical simulations, for both thin and thick silicon films. Whereas the current drive and transconductance are enhanced in volume inversion regime, our results show thatintrinsic capacitances present higher values as well, which may limit the high speed (delay time) behaviour of DG MOSFETs under volume inversion regime.

Computation of an integral basis of a quartic number field

"Vegeu el resum a l'inici del document del fitxer adjunt."

Computation of an integral basis of quartic number field

"Vegeu el resum a l'inici del document del fitxer ajunt."

A functional equation related to the product in a quadratic number field

"Vegeu el resum a l'inici del document del fitxer adjunt."

Extensional flow of nematic liquid crystal under electric field gradient

Systematic asymptotic methods are used to formulate a model for the extensional flow of a thin sheet of nematic liquid crystal. With no external body forces applied, the model is found to be equivalent to the so-called Trouton model for Newtonian sheets (and fi bers), albeit with a modi fied "Trouton ratio". However, with a symmetry-breaking electric field gradient applied, behavior deviates from the Newtonian case, and the sheet can undergo fi nite-time breakup if a suitable destabilizing field is applied. Some simple exact solutions are presented to illustrate the results in certain idealized limits, as well as sample numerical results to the full model equations.

Estudi amb georadar del jaciment arqueològic de Lady Field (Woolston Manor Farm, Somerset, Gran Bretanya)

Projecte de recerca elaborat a partir d’una estada al University of Bristol, Gran Bretanya, durant agost i setembre del 2007. Els objectius del projecte d’estudi del jaciment de Lady Field (Woolston Manor Farm, Somerset, Gran Bretanya) eren, bàsicament, tres: en primer lloc, posar en pràctica els coneixements teòrics assolits durant la formació en prospecció geofísica; en segon lloc, aportar informació complementària a la aportada per la prospecció tradicional i el sondeig amb gradiòmetre magnètic efectuades prèviament per l’equip investigador del centre, arribant a definir millor les estructures poc definides per l’altre sistema i, finalment, obtenir un cas d’estudi sobre un jaciment medieval a Gran Bretanya, on les condicions geològiques i climàtiques, que afecten els resultats de la prospecció, són diferents a les del nostre país. Aquests objectius s’han assolit, ja que s’ha pogut portar a terme una prospecció de camp amb el sistema de georadar, processar les dades i obtenir-ne dades de qualitat i obtenir informació útil i rellevant de cara a la definició de les restes detectades, una vegada feta la interpretació. Els resultats mostren l’aparició en el subsòl del jaciment de quatre possibles fases d’ocupació, entre les que destaquen un moment amb possibles restes d’una antiga xarxa urbana, treballs agrícoles o un sistema de drenatge del terreny. Finalment l’estudi ha pogut constatar que la prospecció amb GPR en aquestes condicions geològiques és possible, tot i que les climàtiques –essencialment la pluja i la humitat del sòl- suposen complicacions a l’hora d’adquirir dades de forma segura per la maquinària i per la qualitat de les dades.

Ontologías Turísticas Geográficas : creación de una ontología sobre rutas turísticas (a Pie o en Bicicleta) por espacios naturales

El turismo es un área en constante crecimiento en la cual, la aparición de las nuevas tecnologías y, fundamentalmente, de Internet, ha tenido un gran impacto en los procedimientos internos de los agentes turísticos y en los métodos de contratación y de búsqueda de información por parte de los usuarios. Por otro lado, la cantidad ingente de información disponible en Internet y el gran desorden existente, provoca la aparición del concepto de Web semántica, una tecnología que dota a las máquinas de un nivel de compresión de la Web suficiente como para hacer de la búsqueda y el acceso a la información una tarea sencilla y natural. Este artículo trata, en primer lugar, de analizar el estado del arte de la Web semántica relacionada con el ámbito del turismo, presentando las ontologías turísticas disponibles en la actualidad para, a continuación, describir el desarrollo de una ontología específica dentro del dominio de las rutas turísticas. Con esta ontología, a través de un ejemplo, se trata de demostrar la utilidad de esta tecnología a la hora de catalogar información relacionada, disponible y dispersa por páginas Web en Internet.