Extreme-value distributions and renormalization group

In the classical theorems of extreme value theory the limits of suitably rescaled maxima of sequences of independent, identically distributed random variables are studied. The vast majority of the literature on the subject deals with affine normalization. We argue that more general normalizations are natural from a mathematical and physical point of view and work them out. The problem is approached using the language of renormalization-group transformations in the space of probability densities. The limit distributions are fixed points of the transformation and the study of its differential around them allows a local analysis of the domains of attraction and the computation of finite-size corrections.

Innovación y Aprendizaje: un nuevo modelo para la formación universitaria: ¿Por qué y para qué? = Innovation and Learning: a New Model for University Education: Why and for What?

The legislative reforms in university matters driven in recent years, beyond the provoked controversies, offer to universities the possibility to develop a new model in line with the European environment, focusing on quality aims and adapting to the socioeconomic current challenges. A new educational model centered on the student, on the formation of specific and transverse competitions, on the improvement of the employability and the access to the labor market, on the attraction and fixation of talent, is an indispensable condition for the effective social mobility and for the homogeneous development of a more responsible and sustainable socioeconomic and productive model

Real time GPS precise positioning of LEO satellites

Report for the scientific sojourn at the German Aerospace Center (DLR) , Germany, during June and July 2006. The main objective of the two months stay has been to apply the techniques of LEO (Low Earth Orbiters) satellites GPS navigation which DLR currently uses in real time navigation. These techniques comprise the use of a dynamical model which takes into account the precise earth gravity field and models to account for the effects which perturb the LEO’s motion (such as drag forces due to earth’s atmosphere, solar pressure, due to the solar radiation impacting on the spacecraft, luni-solar gravity, due to the perturbation of the gravity field for the sun and moon attraction, and tidal forces, due to the ocean and solid tides). A high parameterized software was produced in the first part of work, which has been used to asses which accuracy could be reached exploring different models and complexities. The objective was to study the accuracy vs complexity, taking into account that LEOs at different heights have different behaviors. In this frame, several LEOs have been selected in a wide range of altitudes, and several approaches with different complexity have been chosen. Complexity is a very important issue, because processors onboard spacecrafts have very limited computing and memory resources, so it is mandatory to keep the algorithms simple enough to let the satellite process it by itself.

La crisi Japonesa dels anys 90 : Formació, causes, evolució i recuperació econòmica

Treball que analitza la crisi japonesa dels anys noranta. Es descriu la formació de l'economia bombolla i el seu esclat, les causes de la crisi, el sistema econòmic i polític japonès i la recuperació econòmica començada l'any 2003.

Testing for convergence clubs in income per-capita: A predictive density approach

The paper proposes a technique to jointly test for groupings of unknown size in the cross sectional dimension of a panel and estimates the parameters of each group, and applies it to identifying convergence clubs in income per-capita. The approach uses the predictive density of the data, conditional on the parameters of the model. The steady state distribution of European regional data clusters around four poles of attraction with different economic features. The distribution of incomeper-capita of OECD countries has two poles of attraction and each grouphas clearly identifiable economic characteristics.

Photonic characteristics of Langmuir-Blodgett self-assembled monolayers of colloidal silica particles

Monodispersed colloidal crystals based on silica sub-micrometric particles were synthesized using the Stöber-Fink-Bohn process. The control of nucleation and coalescence result in improved characteristics such as high sphericity and very low size dispersion. The resulting silica particles show characteristics suitable for self-assembling across large areas of closely-packed 2D crystal monolayers by an accurate Langmuir-Blodgett deposition process on glass, fused silica and silicon substrates. Due to their special optical properties, colloidal films have potential applications in fields including photonics, electronics, electro-optics, medicine (detectors and sensors), membrane filters and surface devices. The deposited monolayers of silica particles were characterized by means of FESEM, AFM and optical transmittance measurements in order to analyze their specific properties and characteristics. We propose a theoretical calculation for the photonic band gaps in 2D systems using an extrapolation of the photonic behavior of the crystal from 3D to 2D. In this work we show that the methodology used and the conditions in self-assembly processes are decisive for producing high-quality two-dimensional colloidal crystals by the Langmuir-Blodgett technique.

Brittle to ductile transition in a fiber bundle with strong heterogeneity

We analyze the failure process of a two-component system with widely different fracture strength in the framework of a fiber bundle model with localized load sharing. A fraction 0≤α≤1 of the bundle is strong and it is represented by unbreakable fibers, while fibers of the weak component have randomly distributed failure strength. Computer simulations revealed that there exists a critical composition αc which separates two qualitatively different behaviors: Below the critical point, the failure of the bundle is brittle, characterized by an abrupt damage growth within the breakable part of the system. Above αc, however, the macroscopic response becomes ductile, providing stability during the entire breaking process. The transition occurs at an astonishingly low fraction of strong fibers which can have importance for applications. We show that in the ductile phase, the size distribution of breaking bursts has a power law functional form with an exponent μ=2 followed by an exponential cutoff. In the brittle phase, the power law also prevails but with a higher exponent μ=92. The transition between the two phases shows analogies to continuous phase transitions. Analyzing the microstructure of the damage, it was found that at the beginning of the fracture process cracks nucleate randomly, while later on growth and coalescence of cracks dominate, which give rise to power law distributed crack sizes.

Ancient dispersal of the human fungal pathogen Cryptococcus gattii from the Amazon rainforest

Over the past two decades, several fungal outbreaks have occurred, including the high-profile 'Vancouver Island' and 'Pacific Northwest' outbreaks, caused by Cryptococcus gattii, which has affected hundreds of otherwise healthy humans and animals. Over the same time period, C. gattii was the cause of several additional case clusters at localities outside of the tropical and subtropical climate zones where the species normally occurs. In every case, the causative agent belongs to a previously rare genotype of C. gattii called AFLP6/VGII, but the origin of the outbreak clades remains enigmatic. Here we used phylogenetic and recombination analyses, based on AFLP and multiple MLST datasets, and coalescence gene genealogy to demonstrate that these outbreaks have arisen from a highly-recombining C. gattii population in the native rainforest of Northern Brazil. Thus the modern virulent C. gattii AFLP6/VGII outbreak lineages derived from mating events in South America and then dispersed to temperate regions where they cause serious infections in humans and animals.

Synchronization of symmetric chaotic systems

This paper contains a study of the synchronization by homogeneous nonlinear driving of systems that are symmetric in phase space. The main consequence of this symmetry is the ability of the response to synchronize in more than just one way to the driving systems. These different forms of synchronization are to be understood as generalized synchronization states in which the motions of drive and response are in complete correlation, but the phase space distance between them does not converge to zero. In this case the synchronization phenomenon becomes enriched because there is multistability. As a consequence, there appear multiple basins of attraction and special responses to external noise. It is shown, by means of a computer simulation of various nonlinear systems, that: (i) the decay to the generalized synchronization states is exponential, (ii) the basins of attraction are symmetric, usually complicated, frequently fractal, and robust under the changes in the parameters, and (iii) the effect of external noise is to weaken the synchronization, and in some cases to produce jumps between the various synchronization states available

The love marriage : challenging Victorian myths in Anne Brontë’s 'The Tenant of Wildfell Hall'

La tesina analitza com Anne Brontë desafia el mite del casament romàntic a la novel·la The Tenant of Wildfell Hall. Argumento que aquesta crítica es fa mostrant les conseqüències nefastes d’un matrimoni (entre l’Arthur i l’Helen) basat en l’atracció i en la idea que una dona pot salvar un home de mala vida. Malgrat que la novel·la acaba amb un altre casament (entre l’Helen i en Gilbert), si s’analitza en detall es pot veure que presenta elements subversius. Per exemple, la seva unió està basada en igualtat intel·lectual i compatibilitat de caràcters, enlloc d’igualtat econòmica i social

With a bang, not a whimper: Pricking Germany's "stock market bubble" in 1927 and the slide into depression

In May 1927, the German central bank intervenedindirectly to reduce lending to equity investors.The crash that followed ended the only stockmarket boom during Germany s relative stabilization 1924-28. This paper examines thefactors that lead to the intervention as well asits consequences. We argue that genuine concernabout the exuberant level of the stock market,in addition to worries about an inflow offoreign funds, tipped the scales in favour ofintervention. The evidence strongly suggeststhat the German central bank under HjalmarSchacht was wrong to be concerned aboutstockprices-there was no bubble. Also, theReichsbank was mistaken in its belief thata fall in the market would reduce theimportance of short-term foreign borrowing,and help to ease conditions in the money market.The misguided intervention had important realeffects. Investment suffered, helping to tipGermany into depression.

The dot-com bubble, the Bush deficits and the US current account

Over the past decade the US has experienced widening current account deficits and a steady deterioration of its net foreign asset position. During the second half of the 1990s, this deterioration was fueled by foreign investment in a booming US stock market. During the first half of the 2000s, this deterioration has been fuelled by foreign purchases of rapidly increasing US government debt. A somewhat surprising aspect of the current debate is thatstock market movements and fiscal policy choices have been largely treated as unrelated events. Stock market movements are usually interpreted as reflecting exogenous changes in perceived or real productivity, while budget deficits are usually understood as a mainly political decision. We challenge this view here and develop two alternative interpretations. Both are based on the notion that a bubble (the dot-com bubble) has been driving the stock market, but differ in their assumptions about the interactions between this bubble and fiscal policy (the Bush deficits). The benevolent view holds that a change in investorsentiment led to the collapse of the dot-com bubble and the Bush deficits were a welfare-improving policy response to this event. The cynical view holds instead that the Bush deficits led to the collapse of the dot-com bubble as the new administration tried to appropriate rents from foreign investors. We discuss the implications of each of these views for the future evolution of the US economy and, in particular, its net foreign asset position.

Viscous fingering as a paradigm of interfacial pattern formation: Recent results and new challenges

We review recent results on dynamical aspects of viscous fingering. The Saffman¿Taylor instability is studied beyond linear stability analysis by means of a weakly nonlinear analysis and the exact determination of the subcritical branch. A series of contributions pursuing the idea of a dynamical solvability scenario associated to surface tension in analogy with the traditional selection theory is put in perspective and discussed in the light of the asymptotic theory of Tanveer and co-workers. The inherently dynamical singular effects of surface tension are clarified. The dynamical role of viscosity contrast is explored numerically. We find that the basin of attraction of the Saffman¿Taylor finger depends on viscosity contrast, and that the sensitivity to this parameter is maximal in the usual limit of high viscosity contrast. The competing attractors are identified as closed bubble solutions. We briefly report on recent results and work in progress concerning rotating Hele-Shaw flows, topological singularities and wetting effects, and also discuss future directions in the context of viscous fingering

Three-step pathway engineering results in more incidence rate and higher emission of nerolidol and improved attraction of Diadegma semiclausum

The concentration and ratio of terpenoids in the headspace volatile blend of plants have a fundamental role in the communication of plants and insects. The sesquiterpene (E)-nerolidol is one of the important volatiles with effect on beneficial carnivores for biologic pest management in the field. To optimize de novo biosynthesis and reliable and uniform emission of (E)-nerolidol, we engineered different steps of the (E)-nerolidol biosynthesis pathway in Arabidopsis thaliana. Introduction of a mitochondrial nerolidol synthase gene mediates de novo emission of (E)-nerolidol and linalool. Co-expression of the mitochondrial FPS1 and cytosolic HMGR1 increased the number of emitting transgenic plants (incidence rate) and the emission rate of both volatiles. No association between the emission rate of transgenic volatiles and their growth inhibitory effect could be established. (E)-Nerolidol was to a large extent metabolized to non-volatile conjugates.