N-dimensional dynamical systems exploiting instabilities in full

We report experimental and numerical results showing how certain N-dimensional dynamical systems are able to exhibit complex time evolutions based on the nonlinear combination of N-1 oscillation modes. The experiments have been done with a family of thermo-optical systems of effective dynamical dimension varying from 1 to 6. The corresponding mathematical model is an N-dimensional vector field based on a scalar-valued nonlinear function of a single variable that is a linear combination of all the dynamic variables. We show how the complex evolutions appear associated with the occurrence of successive Hopf bifurcations in a saddle-node pair of fixed points up to exhaust their instability capabilities in N dimensions. For this reason the observed phenomenon is denoted as the full instability behavior of the dynamical system. The process through which the attractor responsible for the observed time evolution is formed may be rather complex and difficult to characterize. Nevertheless, the well-organized structure of the time signals suggests some generic mechanism of nonlinear mode mixing that we associate with the cluster of invariant sets emerging from the pair of fixed points and with the influence of the neighboring saddle sets on the flow nearby the attractor. The generation of invariant tori is likely during the full instability development and the global process may be considered as a generalized Landau scenario for the emergence of irregular and complex behavior through the nonlinear superposition of oscillatory motions

Full instability behavior of N-dimensional dynamical systems with a one-directional nonlinear vector field

We show how certain N-dimensional dynamical systems are able to exploit the full instability capabilities of their fixed points to do Hopf bifurcations and how such a behavior produces complex time evolutions based on the nonlinear combination of the oscillation modes that emerged from these bifurcations. For really different oscillation frequencies, the evolutions describe robust wave form structures, usually periodic, in which selfsimilarity with respect to both the time scale and system dimension is clearly appreciated. For closer frequencies, the evolution signals usually appear irregular but are still based on the repetition of complex wave form structures. The study is developed by considering vector fields with a scalar-valued nonlinear function of a single variable that is a linear combination of the N dynamical variables. In this case, the linear stability analysis can be used to design N-dimensional systems in which the fixed points of a saddle-node pair experience up to N21 Hopf bifurcations with preselected oscillation frequencies. The secondary processes occurring in the phase region where the variety of limit cycles appear may be rather complex and difficult to characterize, but they produce the nonlinear mixing of oscillation modes with relatively generic features

1st National Accessiblity Plan 2004-2012: achieving equal opportunities and full participation through design for all

According to official statistics, disabled people in Spain number 3.5 million and make up 8.8% of the Spanish population. This group of people are increasingly being recognised as members of society with equal rights, and many of their demands are gradually being transformed into solutions that benefit society as a whole. One example is improved accessibility. Accessible built environments are more human and inclusive places, as well as being easier to get around. Improved accessibility is now recognised as a requirement shared by all members of society, although it is achieved thanks to the demands of disabled people and their representatives. The 1st National Accessibility Plan is a strategic framework for action aimed at ensuring that new products, services and built environments are designed to be accessible for as many people as possible (Design for All) and that existing ones are gradually duly adapted.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 1 (2006)

- Resultats de les noves varietats de blat tou. - Recomanació de varietats de blat tou. - Característiques agronòmiques de les varietats recomanades.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 2 (2006)

- Resultats de les noves varietats d’ordi. - Recomanació de varietats d’ordi. - Característiques agronòmiques de les varietats recomanades.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 3 (2006)

- Resultats de les noves varietats de triticale per a gra. - Recomanació de varietats de triticale per a gra. - Característiques agronòmiques de les varietats de triticale. - Aspectes a considerar en l’elecció de les varietats de triticale per a gra.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 4 (2006)

- Resultats de les noves varietats de pèsol proteaginós de primavera per a gra. - Característiques agronòmiques de les varietats de pèsol proteaginós de primavera. - Aspectes a considerar en l’elecció de les varietats de pèsol proteaginós.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 7 (2007)

- Rovell groc del blat. - Rovell bru del blat. - Fungicides pel control dels rovells del blat.

Full informatiu. Cultius extensius - Març 2007

- Recomanacions de fertilització per a la sembra del blat de moro. - Dosis agronòmiques d’aplicació de fems i purins. - Jornada intercomarcal sobre cereal d’hivern a Manresa. - Recomanacions per a la cobertora del cereal d’hivern.

Effects of a nursery CO2 enriched atmosphere on the germination and seedling morphology of two Mediterranean oaks with contrasting leaf habit

Abstract: The use of an enriched CO2 atmosphere in tree nurseries has been envisaged as a promising technique to increase productivity and to obtain seedlings with a higher root/shoot ratio, an essential trait to respond to water stress in Mediterranean-type ecosystems. In that framework, we have analyzed the effects of three levels of atmospheric CO2 concentration (350, 500 and 700 ppm) on the germination rate, growth and morphology of seedlings of two Mediterranean oaks used in reforestation programs: the evergreen Quercus ilex L. and the deciduous Quercus cerrioides Wilk. et Costa. CO2 enrichment increased the germination rate of Q. cerrioides (from 70±7 to 81±3 %) while it decreased that of Q. ilex (from 71±10 to 41±12 %). Seedlings of both species increased approximately 60% their total biomass in response to CO2 enrichment but at two different CO2 concentrations: 500 ppm for Q. cerrioides and 700 ppm for Q. ilex. This increase in seedlings biomass was entirely due to an augmentation of root biomass. Considering germination and biomass partitioning, an enriched CO2 atmosphere might not be appropriate for growing Mediterranean evergreen oaks, such as Q. ilex, since it reduces acorn germination and the only gains in root biomass occur at a high concentration (700 ppm). On the other hand, a moderate CO2 enrichment (500 ppm) appears as a promising nursery technique to stimulate the germination, growth and root/shoot ratio of deciduous oaks, such as Q. cerrioides. Resumen: El uso de una atmósfera enriquecida en CO2 durante la fase de vivero puede contribuir a aumentar la producción viverística, a la vez que ayudar a conseguir plántulas con una mayor relación biomasa subterránea/biomasa aérea, más adecuadas para hacer frente al severo estrés hídrico que generalmente limita el éxito de las repoblaciones en el clima Mediterráneo. En este estudio hemos analizado el efecto de tres niveles de abonado carbónico atmosférico (350, 500 y 750 ppm) en la germinación y morfología de plántulas de encina (Quercus ilex) y roble cerrioide (Quercus cerrioides). Una atmósfera enriquecida en CO2 incrementó la germinación de Q. cerrioides (de 70±7 a 81±3 %) mientras que disminuyó la de Q. ilex (de 71±10 a 41±12 %). Las plántulas de ambas especies incrementaron aproximadamente un 60% su biomasa en respuesta a una mayor concentración de CO2, aunque esta respuesta se produjo a diferentes dosis: 500 ppm en Q. cerrioides y 700 ppm en Q. ilex. El aumento en la biomasa total de las plántulas se debió enteramente a un mayor desarrollo de su sistema radical, Considerando tanto la germinación como los efectos sobre la relación biomasa subterránea/biomasa aérea, una atmósfera enriquecida en CO2 no parece ser un tratamiento adecuado para la producción en vivero de plántulas de Q.ilex, puesto que diminuye su germinación y solo aumenta su sistema radicular a dosis muy elevadas (700 ppm). Por el contrario, un aumento moderado en la concentración de CO2 (500 ppm) aparece como una técnica interesante para estimular el crecimiento y obtener plántulas de Q. cerrioides con un sistema radical más desarrollado.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 6 (2007)

Es presenta un resum dels resultats dels assaigs d’avaluació de varietats de blat de moro de cicle 700 i 600, obtinguts en la zona litoral de Girona, en el marc de la Xarxa d’Experimentació de Varietats de l’IRTA. S’han assajat híbrids convencionals i transgènics derivats del MON810, que incorporen resistència als barrinadors. Amb els resultats de quatre anys d’assaig han destacat principalment les varietats HELEN, ELEONORA, TIETAR, PR32R42, ASTURIAL i PR33P66, sense diferències significatives entre elles. Les varietats transgèniques s’han assajat un màxim de tres anys havent mostrat algunes d’elles una alta productivitat. Entre aquestes han destacat PR32P76, DKC6575, PR33P67 i HELEN Bt, si bé sense diferències significatives amb el testimoni ELEONORA. També amb els resultats de tres anys d’assaig cal remarcar la varietat de blat de moro convencional PR32W86, que ha mostrat un nivell productiu similar a les millors transgèniques. Amb només dos anys d’assaig ha destacat principalment la varietat transgènica BELES SUR.

Full Tècnic. Conreus Extensius. Comarques de Girona, núm. 9 (2007)

Es presenta un resum dels resultats dels assaigs d’avaluació de varietats de blat tou obtinguts en el marc de la Xarxa d’Experimentació de Varietats de l’IRTA.