Modelling of bird distribution under complex mediterranean landscape dynamics: open habitat birds and fire (MEDFIRE)

Report for the scientific sojourn at the Simon Fraser University, Canada, from July to September 2007. General context: landscape change during the last years is having significant impacts on biodiversity in many Mediterranean areas. Land abandonment, urbanisation and specially fire are profoundly transforming large areas in the Western Mediterranean basin and we know little on how these changes influence species distribution and in particular how these species will respond to further change in a context of global change including climate. General objectives: integrate landscape and population dynamics models in a platform allowing capturing species distribution responses to landscape changes and assessing impact on species distribution of different scenarios of further change. Specific objective 1: develop a landscape dynamic model capturing fire and forest succession dynamics in Catalonia and linked to a stochastic landscape occupancy (SLOM) (or spatially explicit population, SEPM) model for the Ortolan bunting, a species strongly linked to fire related habitat in the region. Predictions from the occupancy or spatially explicit population Ortolan bunting model (SEPM) should be evaluated using data from the DINDIS database. This database tracks bird colonisation of recently burnt big areas (&50 ha). Through a number of different SEPM scenarios with different values for a number of parameter, we should be able to assess different hypothesis in factors driving bird colonisation in new burnt patches. These factors to be mainly, landscape context (i.e. difficulty to reach the patch, and potential presence of coloniser sources), dispersal constraints, type of regenerating vegetation after fire, and species characteristics (niche breadth, etc).

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.

Bargaining one-dimensional policies and the efficiency of super majority rules

We consider negotiations selecting one-dimensional policies. Individuals have single-peaked preferences, and they are impatient. Decisions arise from a bargaining game with random proposers and (super) majority approval, ranging from the simple majority up to unanimity. The existence and uniqueness of stationary subgame perfect equilibrium is established, and its explicit characterization provided. We supply an explicit formula to determine the unique alternative that prevails, as impatience vanishes, for each majority. As an application, we examine the efficiency of majority rules. For symmetric distributions of peaks unanimity is the unanimously preferred majority rule. For asymmetric populations rules maximizing social surplus are characterized.

Polynomial functors and trees

We explore the relationship between polynomial functors and trees. In the first part we characterise trees as certain polynomial functors and obtain a completely formal but at the same time conceptual and explicit construction of two categories of rooted trees, whose main properties we describe in terms of some factorisation systems. The second category is the category Ω of Moerdijk and Weiss. Although the constructions are motivated and explained in terms of polynomial functors, they all amount to elementary manipulations with finite sets. Included in Part 1 is also an explicit construction of the free monad on a polynomial endofunctor, given in terms of trees. In the second part we describe polynomial endofunctors and monads as structures built from trees, characterising the images of several nerve functors from polynomial endofunctors and monads into presheaves on categories of trees. Polynomial endofunctors and monads over a base are characterised by a sheaf condition on categories of decorated trees. In the absolute case, one further condition is needed, a projectivity condition, which serves also to characterise polynomial endofunctors and monads among (coloured) collections and operads.

Dynamics in Thompson's group F

We describe an explicit relationship between strand diagrams and piecewise-linear functions for elements of Thompson’s group F. Using this correspondence, we investigate the dynamics of elements of F, and we show that conjugacy of one-bump functions can be described by a Mather-type invariant.

Adopcions internacionals: anàlisi de les motivacions inicials per esdevenir pares adoptius a Catalunya

En els darrers anys Espanya, i concretament Catalunya, s'ha convertit en el país amb major nombre d'adopcions per habitant del món. Aquest fet ens duu a plantejar-nos quines són les motivacions que impulsen als sol•licitants a voler adoptar. En aquest estudi fem una categorització de les principals motivacions inicials de l'adopció internacional manifestades en els processos de valoració per a l'obtenció del Certificat d'Idoneïtat en una mostra catalana de 331 persones. Els resultats obtinguts ens indiquen que la majoria de sol•licitants adopta pensant en les seves necessitats i en les seves dificultats per a procrear i no tant en el menor que volen adoptar.

Still in the Era of Area Studies? Political-Scientific Perspectives on European Competition Policy in the 2000s

This note reviews the political-scientific literature on European competition policy (ECP) in the 2000s. Based on a data set extracted from four well-known journals, and using an upfront methodology and explicit criteria, it analyzes the literature both quantitatively and qualitatively. On the quantitative side, it shows that, although a few sub-policy areas are still neglected, ECP is not the under-researched policy it used to be. On the qualitative side, the literature has greatly improved since the 1990s: Almost all articles now present a clear research question, and most advance specific theoretical claims/hypotheses. Yet, improvements can be made on research design, statistical testing, and, above all, state-of-the-art theorizing (e.g. in the game-theoretical treatment of delegation problems). Indeed, it is paradoxical that ECP specialists do not pay more attention to theoretical questions which are so central to the actual policy area they study.

The role of fixed delays in neuronal rate models

Fixed delays in neuronal interactions arise through synaptic and dendritic processing. Previous work has shown that such delays, which play an important role in shaping the dynamics of networks of large numbers of spiking neurons with continuous synaptic kinetics, can be taken into account with a rate model through the addition of an explicit, fixed delay. Here we extend this work to account for arbitrary symmetric patterns of synaptic connectivity and generic nonlinear transfer functions. Specifically, we conduct a weakly nonlinear analysis of the dynamical states arising via primary instabilities of the stationary uniform state. In this way we determine analytically how the nature and stability of these states depend on the choice of transfer function and connectivity. While this dependence is, in general, nontrivial, we make use of the smallness of the ratio in the delay in neuronal interactions to the effective time constant of integration to arrive at two general observations of physiological relevance. These are: 1 - fast oscillations are always supercritical for realistic transfer functions. 2 - Traveling waves are preferred over standing waves given plausible patterns of local connectivity.

Homotopy Batalin-Vilkovisky algebras

This paper provides an explicit cofibrant resolution of the operad encoding Batalin-Vilkovisky algebras. Thus it defines the notion of homotopy Batalin-Vilkovisky algebras with the required homotopy properties. To define this resolution we extend the theory of Koszul duality to operads and properads that are defined by quadratic and linear relations. The operad encoding Batalin-Vilkovisky algebras is shown to be Koszul in this sense. This allows us to prove a Poincaré-Birkhoff-Witt Theorem for such an operad and to give an explicit small quasi-free resolution for it. This particular resolution enables us to describe the deformation theory and homotopy theory of BV-algebras and of homotopy BV-algebras. We show that any topological conformal field theory carries a homotopy BV-algebra structure which lifts the BV-algebra structure on homology. The same result is proved for the singular chain complex of the double loop space of a topological space endowed with an action of the circle. We also prove the cyclic Deligne conjecture with this cofibrant resolution of the operad BV. We develop the general obstruction theory for algebras over the Koszul resolution of a properad and apply it to extend a conjecture of Lian-Zuckerman, showing that certain vertex algebras have an explicit homotopy BV-algebra structure.

On rigid analytic uniformizations of Jacobians of Shimura curves

The main goal of this article is to give an explicit rigid analytic uniformization of the maximal toric quotient of the Jacobian of a Shimura curve over Q at a prime dividing exactly the level. This result can be viewed as complementary to the classical theorem of Cerednik and Drinfeld which provides rigid analytic uniformizations at primes dividing the discriminant. As a corollary, we offer a proof of a conjecture formulated by M. Greenberg in hispaper on Stark-Heegner points and quaternionic Shimura curves, thus making Greenberg's construction of local points on elliptic curves over Q unconditional.

Equations of hyperelliptic Shimura curves

We describe an algorithm that computes explicit models of hyperelliptic Shimura curves attached to an indefinite quaternion algebra over Q and Atkin-Lehner quotients of them. It exploits Cerednik-Drinfeld’s nonarchimedean uniformisation of Shimura curves, a formula of Gross and Zagier for the endomorphism ring of Heegner points over Artinian rings and the connection between Ribet’s bimodules and the specialization of Heegner points, as introduced in [21]. As an application, we provide a list of equations of Shimura curves and quotients of them obtained by our algorithm that had been conjectured by Kurihara.

Civil war and foreign influence

We study a symmetric information bargaining model of civil war where a third (foreign) party can affect the probabilities of winning the conflict and the size of the post conflict spoils. We show that the possible alliance with a third party makes peaceful agreements difficult to reach and might lead to new commitment problems that trigger war. Also, we argue that the foreign party is likely to induce persistent informational asymmetries which might explain long lasting civil wars. We explore both political and economic incentives for a third party to intervene. The explicit consideration of political incentives leads to two predictions that allow for identifying the influence of foreign intervention on civil war incidence. Both predictions are confirmed for the case of the U.S. as a potential intervening nation: (i) civil wars around the world are more likely under Republican governments and (ii) the probability of civil wars decreases with U.S. presidential approval rates.

Mecanismes neuronals de la facilitació de l'aprenentatge i la memoria per autoestimulació eléctrica intracranial en rates: espines dendrítiques

La potenciación de procesos de aprendizaje y memoria por autoestimación eléctrica intracraneal (AEIC) se ha observado principalmente en tareas de aprendizaje de tipo implícito, caracterizado por necesitar de múltiples ensayos y por dar lugar a una respuesta conductual rígida. Los efectos de la AEIC sobre formas de aprendizaje consideradas más complejas, como la memoria de navegación espacial, son menos conocidos. En nuestro laboratorio hemos observado recientemente que el tratamiento de AEIC es también capaz de facilitar tanto la adquisición como la retención de una tarea relacional, en el laberinto acuático de Morris (MWM) (Ruiz-Medina et al., 2008). El proyecto de investigación objeto de esta memoria continúa el estudio de este efecto potenciador yendo un paso más allá al profundizar en los mecanismos neurales de este efecto. Lo relativo a las espinas dendríticas, su tamaño, forma y aparición es uno de los campos más actuales en el estudio de las bases neurales de la memoria. Trabajos previos apuntan a un incremento en la densidad de espinas inmaduras -las consideradas de aprendizaje- como efecto tanto del entrenamiento en el MWM como de la AEIC. Relacionar la potenciación de memoria en el MWM resultado de la AEIC con cambios significativos en la población de espinas dendríticas hipocampales sería uno de los principales objetivos del presente trabajo, que se realizará en colaboración con el Instituto Ramón y Cajal de Madrid.

Regulación de la movilidad celular por Profilina 1

Mi proyecto de tesis se basaba en el estudio del papel de profilina 1 en la formación de lamelas, para ello generamos una proteína recombinante y transducible, con el objetivo de poder modificar los niveles endógenos de profilina. Objetivos: i-caracterización bioquímica los tres sitios de union conocidos de la proteína de transducción, el sitio de unión a fosfo-inocitoles (PIP), el de unión a actina (Ac) y el de unión a poli-prolinas (PLP). ii-estudio de la polimerización in-vitro de actina - PTD4-Profilina1 iii-estudio de las proteínas componentes de lamelas inducidas por PTD4-Profilina1. Plan de trabajo: i-Para comprobar la funcionalidad los 3 sitios de unión fueron necesarias las primeras 6 semanas, ya que en primer lugar había que expresar y purificar el peptido Srv2, necesario para el ensayo de PLP. En segundo lugar, se obtuvieron los datos de las concentraciones adecuadas de lípidos para el ensayo de fosfo-inocitoles y por ultimo, se purifico la actina necesaria para el ensayo de unión a actina. Una vez establecida la funcionalidad de la proteína, se procedió a: ii-el estudio de polimerización in-vitro, que llevo 2 semanas. Demostrando que in-vitro era capaz de inhibir la polimerización de una manera similar a la endógena. Una vez terminados estos ensayos, se procedio a: iii-la caracterización inmunohistoquímica de las proteínas componentes de la lamela que fue llevado a cabo en 4 semanas. Para ello se usaron anticuerpos contra: alfa-actinina, talina, vinculina, ENA/Vasp y paxillina. Conclusiones: i-las propiedades bioquímicas de la PTD4-Profilina1 son similares a las de la profilina endógena. ii-los estudios de polimerización indican que la polimerización se produce de manera similar a la endogena. iii-los ensayos de inmunohistoquímica sugieren que, talina esta ausente y que las demás están presentes aunque en menor concentración y con otra distribución comparadas con los controles.

A geometric mechanism of diffusion: Rigorous verification in a priori unstable Hamiltonian systems

In this paper we consider a representative a priori unstable Hamiltonian system with 2+1/2 degrees of freedom, to which we apply the geometric mechanism for diffusion introduced in the paper Delshams et al., Mem.Amer.Math. Soc. 2006, and generalized in Delshams and Huguet, Nonlinearity 2009, and provide explicit, concrete and easily verifiable conditions for the existence of diffusing orbits. The simplification of the hypotheses allows us to perform explicitly the computations along the proof, which contribute to present in an easily understandable way the geometric mechanism of diffusion. In particular, we fully describe the construction of the scattering map and the combination of two types of dynamics on a normally hyperbolic invariant manifold.