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.

Moral hazard and non-exclusive contracts

This paper studies equilibria for economies characterized by moral hazard(hidden action), in which the set of contracts marketed in equilibrium isdetermined by the interaction of financial intermediaries.The crucial aspect of the environment that we study is thatintermediaries are restricted to trade non-exclusive contracts: theagents' contractual relationships with competing intermediaries cannot bemonitored (or are not contractible upon). We fully characterize equilibrium allocations and contracts. In thisset-up equilibrium allocations are clearly incentive constrainedinefficient. A robust property of equilibria with non-exclusivity isthat the contracts issued in equilibrium do not implement the optimalaction. Moreover we prove that, whenever equilibrium contracts doimplement the optimal action, intermediaries make positive profits andequilibrium allocations are third best inefficient (where the definitionof third best efficiency accounts for constraints which capture thenon-exclusivity of contracts).

Public and private saving and investment

We decompose aggregate saving and investment into its publicand private components and then document a variety of ``stylized facts''associated with saving and investment rates for a sample of15 countries over the period 1975--1989. In order to seewhether these empirical relationships are consistent with aworld of perfect capital mobility we develop a multi--countrymodel with free trade in a riskfree bond and calibrate it tothe fifteen OECD countries. We pay special attential tomodeling the fiscal policy rules. The model performsremarkably well in accounting for a wide variety of timeseries relationships. Nonetheless the model is not able to capture the crosssectional aspect of the data. In particular, the model cannot accountfor both the large cross country correlation between aggregate saving and investmentrates and the very negative cross country relationship between the public andprivate saving minus investment gaps.

Bifurcations and chaos in single-roll natural convection with low Prandtl number

Convective flows of a small Prandtl number fluid contained in a two-dimensional cavity subject to a lateral thermal gradient are numerically studied by using different techniques. The aspect ratio (length to height) is kept at around 2. This value is found optimal to make the flow most unstable while keeping the basic single-roll structure. Two cases of thermal boundary conditions on the horizontal plates are considered: perfectly conducting and adiabatic. For increasing Rayleigh numbers we find a transition from steady flow to periodic oscillations through a supercritical Hopf bifurcation that maintains the centrosymmetry of the basic circulation. For a Rayleigh number of about ten times that of the Hopf bifurcation the system initiates a complex scenario of bifurcations. In the conductive case these include a quasiperiodic route to chaos. In the adiabatic one the dynamics is dominated by the interaction of two Neimark-Sacker bifurcations of the basic periodic solutions, leading to the stable coexistence of three incommensurate frequencies, and finally to chaos. In all cases, the complex time-dependent behavior does not break the basic, single-roll structure.

Three-dimensional aspects of fluid flows in channels. II. Effects of meniscus and thin film regimes on viscous fingers

We perform a three-dimensional study of steady state viscous fingers that develop in linear channels. By means of a three-dimensional lattice-Boltzmann scheme that mimics the full macroscopic equations of motion of the fluid momentum and order parameter, we study the effect of the thickness of the channel in two cases. First, for total displacement of the fluids in the channel thickness direction, we find that the steady state finger is effectively two-dimensional and that previous two-dimensional results can be recovered by taking into account the effect of a curved meniscus across the channel thickness as a contribution to surface stresses. Second, when a thin film develops in the channel thickness direction, the finger narrows with increasing channel aspect ratio in agreement with experimental results. The effect of the thin film renders the problem three-dimensional and results deviate from the two-dimensional prediction.

Three-dimensional aspects of fluid flows in channels. II. Effects of meniscus and thin film regimes on viscous fingers

We perform a three-dimensional study of steady state viscous fingers that develop in linear channels. By means of a three-dimensional lattice-Boltzmann scheme that mimics the full macroscopic equations of motion of the fluid momentum and order parameter, we study the effect of the thickness of the channel in two cases. First, for total displacement of the fluids in the channel thickness direction, we find that the steady state finger is effectively two-dimensional and that previous two-dimensional results can be recovered by taking into account the effect of a curved meniscus across the channel thickness as a contribution to surface stresses. Second, when a thin film develops in the channel thickness direction, the finger narrows with increasing channel aspect ratio in agreement with experimental results. The effect of the thin film renders the problem three-dimensional and results deviate from the two-dimensional prediction.

Surface-dependent strategies and energy flux in benthic marine communities or, why corals do not exist in the Mediterranean

Most structure-building organisms in rocky benthic communities are surface-dependent because their energy inputs depend mainly on the surface they expose to water. Two photosynthetic strategies, divided into calcareous and non calcareous algae, strict suspension-feeders and photosynthetic suspension feeders (e.g. hermatypic corals) are the four main strategies evolutively acquired by benthic organisms. Competition between those strategies occur in relation to productivity of the different species, in such a way that, for given environmental conditions, species with a higher growth (P/B ratio) would dominate. At a worldwide scale, littoral marine benthos can he considered to fit into the four fields defined by two main axes: the first, relates to productivity and relies atrophic and oligotrophic waters and the second is defined by the degree of environmental variability or seasonality (from high to low). Coral reefs (marine ecosystems dominated by photosynthetic suspension feeders) develop in the space of oligotrophic areas with low variability, while kelp beds (marine ecosystem dominated by large, non calcareous algae) are to be found only in eutrophic places with a high variability. The space of eutrophic waters with a low variability do not has specially adapted, high structured, benthic marine ecosystems, and in these conditions opportunistic algae and animals predominate. Finally, photophilic mediterranean benthos -devoid of kelps and without hermatypic corals- typifies the field of oligotrophic areas with high variability; in its more genuine aspect, Mediterranean benthos is represented by small algae with a high percentage of calcareous thallii. In all cases strict suspension-feeders compete successfully with photosynthetic organisms only in situations of low irradiances or very high inputs of POM. In its turn, Mediterranean rocky benthos, in spite of its relative uniformity, is geographically organized along the same axes. The Gulf of Lions and the insular bottoms (Balearic Islands, for example) would correspond to the extremes of eutrophic-high variability areas and oligotrophic-low variability areas, respectively. Irradiance, nutrient and POM concentration, and hydrodynamism are the three variables which mainly affect the distribution of the different surface-dependent strategies, and thus, these parameters are of paramount interest for understanding the trophic structure of Mediterranean benthic communities. In environments non limited by light, nutrient availability, defined as the product between nutrient -POM concentration and hydrodynamism, states the dominance of calcareous versus non calcareous algae. Calcareous algae dominate in oligotrophic waters while non-calcareous algae dominate in moderately eutrophic waters. In light-limited environments, passive suspension feeders (octocorallaria, gorgonians) become dominant species if POM availability is enhanced by a high hydrodynamism (strong currents); in waters with a low charge of POM organisms of other groups, mainly active suspension feeders, predominate (sponges, bryozoans, scleractiniarians). In any case, there always exists a very variable bathymetric zone, depending on light attenuation and nutrient-POM availability, where encrusting calcareous algae strongly compete with suspension feeders (coralligenous).

Calidad de vida y percepción de la desigualdad de la mujer en la ciudad de Girona = Quality of life and inequality perception’s of women in the city of Girona

La igualdad de oportunidades para las mujeres, como factor clave para avanzar en la consecución de calidad de vida preocupa hoy en día a la sociedad en general y alas instituciones en particular. Antes de la elaboración de programas de intervención social es necesario conocer las percepciones de las propias mujeres acerca de sus problemas y de sus necesidades. Siguiendo esta línea de pensamiento presentamos un trabajo empírico en el que analizamos las percepciones de las mujeres de la ciudad de Girona, centrándonos en dos aspectos de manera particular: la percepción de calidad de vida proporcionada por su ciudad y la percepción de desigualdad de oportunidades y/o de discriminación. Los principales resultados, obtenidos a partir de las respuestas a un cuestionario auto-administrado, y proporcionados por una muestra de mujeres seleccionadas aleatoriamente a partir de un muestreo estratificado geográficamente, indican que en general están satisfechas con su ciudad aunque detectamos las principales causas de insatisfacción. Por otra parte, tas principales fuentes de desigualdad se refieren al mundo laboral (menos salario por el mismo trabajo, dificultades de encontrar trabajo si tienen hijos o si son ya mayores), y en la actitud general de la sociedad en el sentido de tener que cumplir el papel que tradicionalmente se les ha asignado

The origins and impact of primate segmental duplications

Duplicated sequences are substrates for the emergence of new genes and are an important source of genetic instability associated with rare and common diseases. Analyses of primate genomes have shown an increase in the proportion of interspersed segmental duplications (SDs) within the genomes of humans and great apes. This contrasts with other mammalian genomes that seem to have their recently duplicated sequences organized in a tandem configuration. In this review, we focus on the mechanistic origin and impact of this difference with respect to evolution, genetic diversity and primate phenotype. Although many genomes will be sequenced in the future, resolution of this aspect of genomic architecture still requires high quality sequences and detailed analyses.

Reporting a program evaluation: Needs, program plan, intervention, and decisions

The approach to intervention programs varies depending on the methodological perspective adopted. This means that health professionals lack clear guidelines regarding how best to proceed, and it hinders the accumulation of knowledge. The aim of this paper is to set out the essential and common aspects that should be included in any program evaluation report, thereby providing a useful guide for the professional regardless of the procedural approach used. Furthermore, the paper seeks to integrate the different methodologies and illustrate their complementarity, this being a key aspect in terms of real intervention contexts, which are constantly changing. The aspects to be included are presented in relation to the main stages of the evaluation process: needs, objectives and design (prior to the intervention), implementation (during the intervention), and outcomes (after the intervention). For each of these stages the paper describes the elements on which decisions should be based, highlighting the role of empirical evidence gathered through the application of instruments to defined samples and according to a given procedure.

Shrouded costs of government: The political economy of state and local public pensions

Why do public-sector workers receive so much of their compensation in the formof pensions and other benefits? This paper presents a political economy model inwhich politicians compete for taxpayers' and government employees' votes by promising compensation packages, but some voters cannot evaluate every aspect of promisedcompensation. If pension packages are "shrouded", so that public-sector workers better understand their value than ordinary taxpayers, then compensation will be highlyback-loaded. In equilibrium, the welfare of public-sector workers could be improved,holding total public-sector costs constant, if they received higher wages and lowerpensions. Centralizing pension determination has two offsetting effects on generosity:more state-level media attention helps taxpayers better understand pension costs, andthat reduces pension generosity; but a larger share of public-sector workers will votewithin the jurisdiction, which increases pension generosity. A short discussion of pensions in two decentralized states (California and Pennsylvania) and two centralizedstates (Massachusetts and Ohio) suggests that centralization appears to have modestlyreduced pensions, but, as the model suggests, this is unlikely to be universal.

Job accessibility, employment and job-education mismatch in the metropolitan area of Barcelona

This paper analyses the effect of job accessibility by public and private transport on labour market outcomes in the metropolitan area of Barcelona. Beyond employment, we consider the effect of job accessibility on job-education mismatch, which represents a relevant aspect of job quality. We adopt a recursive system of equations that models car availability, employment and mismatch. Public transport accessibility appears as an exogenous variable in the three equations. Even though it may reflect endogenous residential sorting, falsification proofs suggest that the estimated effect of public transport accessibility is not entirely driven by the endogenous nature of residential decisions.

Identifying the preferred subset of enzymatic profiles in nonlinear kinetic metabolic models via multiobjective global optimization and pareto filters

Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA) representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study that optimizes the ethanol production in the fermentation of Saccharomyces cerevisiae.

More evidence concerning the aspect hypothesis: The acquisition of English progressive aspect by Catalan-Spanish instructed learners

A robust finding of studies investigating the Aspect Hypothesis is that learners at early stages of acquisition show a strong preference for using the progressive aspect as associated with activity verbs. As they advance in their acquisition of the second or foreign language, learners move from this prototypical association to associations traditionally considered to be more peripheral (e.g.-ing with accomplishments or achievements). Within this framework, the goal of this paper is to provide further evidence from groups of learners with different proficiency levels with regard to the acquisition of progressive aspect by tutored learners of English who are bilingual Catalan-Spanish. This is done by eliciting data by means of two different task types and by looking at both tokens and types. Our results are consistent with previous research according to which-ing morphology is closely associated with durative lexical aspect, although not necessarily with activity predicates. The study also shows that the type of task has an influence on the frequency and the distribution of learners" progressive forms.

Spontaneous Speech and Emotional Response modeling based on One-class classifier oriented to Alzheimer Disease diagnosis

The purpose of our project is to contribute to earlier diagnosis of AD and better estimates of its severity by using automatic analysis performed through new biomarkers extracted from non-invasive intelligent methods. The methods selected in this case are speech biomarkers oriented to Sponta-neous Speech and Emotional Response Analysis. Thus the main goal of the present work is feature search in Spontaneous Speech oriented to pre-clinical evaluation for the definition of test for AD diagnosis by One-class classifier. One-class classifi-cation problem differs from multi-class classifier in one essen-tial aspect. In one-class classification it is assumed that only information of one of the classes, the target class, is available. In this work we explore the problem of imbalanced datasets that is particularly crucial in applications where the goal is to maximize recognition of the minority class as in medical diag-nosis. The use of information about outlier and Fractal Dimen-sion features improves the system performance.