The role of central bank operating procedures in an economy with productive government spending

The choice of either the rate of monetary growth or the nominal interest rate as the instrument controlled by monetary authorities has both positive and normative implications for economic performance. We reexamine some of the issues related to the choice of the monetary policy instrument in a dynamic general equilibrium model exhibiting endogenous growth in which a fraction of productive government spending is financed by means of issuing currency. When we evaluate the performance of the two monetary instruments attending to the fluctuations of endogenous variables, we find that the inflation rate is less volatile under nominal interest rate targeting. Concerning the fluctuations of consumption and of the growth rate, both monetary policy instruments lead to statistically equivalent volatilities. Finally, we show that none of these two targeting procedures displays unambiguously higher welfare levels.

Optimal regulation of specialized medical care in a mixed system

We study the optimal public intervention in setting minimum standards of formation for specialized medical care. The abilities the physicians obtain by means of their training allow them to improve their performance as providers of cure and earn some monopoly rents.. Our aim is to characterize the most efficient regulation in this field taking into account different regulatory frameworks. We find that the existing situation in some countries, in which the amount of specialization is controlled, and the costs of this process of specialization are publicly financed, can be supported as the best possible intervention.

Subjective income expectations, canonical models and income risk

Expectations are central to behaviour. Despite the existence of subjective expectations data, the standard approach is to ignore these, to hypothecate a model of behaviour and to infer expectations from realisations. In the context of income models, we reveal the informational gain obtained from using both a canonical model and subjective expectations data. We propose a test for this informational gain, and illustrate our approach with an application to the problem of measuring income risk.

La transmissió dels models bizantins d’Itàlia a Hispània

Estudi realitzat a partir d’una estada a Roma entre el 7 de gener i el 28 de febrer de 2006. S’ estudia la influència de les produccions bizantines i orientals a la península Ibèrica, a l’època visigoda i més enllà, fins i tot justificant una cronologia dels segles VIII-X dC per a molts dels capitells tradicionalment denominats mossàrabs del nord-oest peninsular. A més, s’enuncia una via per la investigació de les possibles influències llombardes a la península Ibèrica. També es comenten les relacions entre els capitells del nord-est peninsular i els de la Gàl.lia.

Els models d'organització metropolitana: el cas de Montreal

Estudi realitzat a partir d’una estada a l’Institut National de Recherche Scientifique, de Montreal, entre l’1 de setembre i el 30 de desembre de 2005. S’analitza el model d’organització de l’àrea metropolitana de Montreal (Canadà) després de la reforma realitzada entre 2000 i 2002, així com les causes que van conduïr a adoptar-lo.

Estudi comparatiu dels models d’organització de les últimes sis seus olímpiques

Transcripció de la intervenció del Sr. Gabriel Colomé en el Curs Universitari sobre Olimpisme que va organitzar el Centre d'Estudis Olí­mpics (CEO-UAB) el febrer de 1992. L'autor amb aquest text es proposa dos objectius principals: d'una banda, analitzar la influència de l'entorn sociopolí­tic sobre l'estructura organitzativa del Comitè Organitzador dels Jocs; de l'altra, veure com afecta el tipus de finançament en l'estructura i la infrastructura dels mateixos Jocs, i quines diferències hi ha entre els Jocs de 1972 i els següents fins a arribar a Barcelona.

Inhibitory effect of cyclophosphamide on the biosynthesis of a perchloro-soluble protein fraction of ehrlich ascites carcinoma cells

The perchloro-soluble mucroptotein fraction was determined in the cells of Ehrlich ascites carcinoma on the 10th and 12th days post-inoculation of the tumor. After 3 days of a single subcutaneous dose of cyclophosphamide (200 mg/kg) the mucoprotein levels were found considerable lower. This difference was highly significant statistically.

Isolation of an enriched plasma membrame subpellicular microtubule fraction of Leishmania mexicana amazonensis

A cell fractionation procedure previously developed for Trypanosoma cruzi was applied to isolated the plasma membrane of promastigotes of Leishania mexicana amazonensis. The cell, swollen in an hypotonic mediun, were disrupted in the presence of a nonionic detergent and the membrane fraction isolated by differencial centrifugation. Electron microscopy showed that the fraction consisted of pieces of the plasma membrane associated with subpellicular microtubules. It was also shown that this fraction is able to induce cell-mediated immune response in mice.

Data size sufficiency analyses of haplotype inference algortihms

We present experimental and theoretical analyses of data requirements for haplotype inference algorithms. Our experiments include a broad range of problem sizes under two standard models of tree distribution and were designed to yield statistically robust results despite the size of the sample space. Our results validate Gusfield's conjecture that a population size of n log n is required to give (with high probability) sufficient information to deduce the n haplotypes and their complete evolutionary history. The experimental results inspired our experimental finding with theoretical bounds on the population size. We also analyze the population size required to deduce some fixed fraction of the evolutionary history of a set of n haplotypes and establish linear bounds on the required sample size. These linear bounds are also shown theoretically.

Well-posedness and invariant measures for HJM models with deterministic volatility and Lévy noise

We give sufficient conditions for existence, uniqueness and ergodicity of invariant measures for Musiela's stochastic partial differential equation with deterministic volatility and a Hilbert space valued driving Lévy noise. Conditions for the absence of arbitrage and for the existence of mild solutions are also discussed.

Estimation of dynamic latent variable models using simulated nonparametric moments

Given a model that can be simulated, conditional moments at a trial parameter value can be calculated with high accuracy by applying kernel smoothing methods to a long simulation. With such conditional moments in hand, standard method of moments techniques can be used to estimate the parameter. Since conditional moments are calculated using kernel smoothing rather than simple averaging, it is not necessary that the model be simulable subject to the conditioning information that is used to define the moment conditions. For this reason, the proposed estimator is applicable to general dynamic latent variable models. Monte Carlo results show that the estimator performs well in comparison to other estimators that have been proposed for estimation of general DLV models.

Generalized factor models: a bayesian approach

There is recent interest in the generalization of classical factor models in which the idiosyncratic factors are assumed to be orthogonal and there are identification restrictions on cross-sectional and time dimensions. In this study, we describe and implement a Bayesian approach to generalized factor models. A flexible framework is developed to determine the variations attributed to common and idiosyncratic factors. We also propose a unique methodology to select the (generalized) factor model that best fits a given set of data. Applying the proposed methodology to the simulated data and the foreign exchange rate data, we provide a comparative analysis between the classical and generalized factor models. We find that when there is a shift from classical to generalized, there are significant changes in the estimates of the structures of the covariance and correlation matrices while there are less dramatic changes in the estimates of the factor loadings and the variation attributed to common factors.

Species distribution models reveal apparent competitive and facilitative effects of a dominant species on the distribution of tundra plants

Abiotic factors are considered strong drivers of species distribution and assemblages. Yet these spatial patterns are also influenced by biotic interactions. Accounting for competitors or facilitators may improve both the fit and the predictive power of species distribution models (SDMs). We investigated the influence of a dominant species, Empetrum nigrum ssp. hermaphroditum, on the distribution of 34 subordinate species in the tundra of northern Norway. We related SDM parameters of those subordinate species to their functional traits and their co-occurrence patterns with E. hermaphroditum across three spatial scales. By combining both approaches, we sought to understand whether these species may be limited by competitive interactions and/or benefit from habitat conditions created by the dominant species. The model fit and predictive power increased for most species when the frequency of occurrence of E. hermaphroditum was included in the SDMs as a predictor. The largest increase was found for species that 1) co-occur most of the time with E. hermaphroditum, both at large (i.e. 750 m) and small spatial scale (i.e. 2 m) or co-occur with E. hermaphroditum at large scale but not at small scale and 2) have particularly low or high leaf dry matter content (LDMC). Species that do not co-occur with E. hermaphroditum at the smallest scale are generally palatable herbaceous species with low LDMC, thus showing a weak ability to tolerate resource depletion that is directly or indirectly induced by E. hermaphroditum. Species with high LDMC, showing a better aptitude to face resource depletion and grazing, are often found in the proximity of E. hermaphroditum. Our results are consistent with previous findings that both competition and facilitation structure plant distribution and assemblages in the Arctic tundra. The functional and co-occurrence approaches used were complementary and provided a deeper understanding of the observed patterns by refinement of the pool of potential direct and indirect ecological effects of E. hermaphroditum on the distribution of subordinate species. Our correlative study would benefit being complemented by experimental approaches.