Showing papers by "Pompeu Fabra University published in 1998"
TL;DR: This paper examined the business cycle properties of a small set of real US macroeconomic time series using a variety of detrending methods and found that both quantitatively and qualitatively "stylized facts" of US business cycles vary widely across detrended methods and that alternative detending filters extract different types of information from the data.
1,023 citations
TL;DR: It seems unlikely that altitude has exerted a major selective pressure on mitochondrial genes in central Asian populations, because lowland and highland Kirghiz mtDNA sequences are very similar, and the analysis of molecular variance has revealed that the fraction of mitochondrial genetic variance due to altitude is not significantly different from zero.
Abstract: Central Asia is a vast region at the crossroads of different habitats, cultures, and trade routes. Little is known about the genetics and the history of the population of this region. We present the analysis of mtDNA control-region sequences in samples of the Kazakh, the Uighurs, the lowland Kirghiz, and the highland Kirghiz, which we have used to address both the population history of the region and the possible selective pressures that high altitude has on mtDNA genes. Central Asian mtDNA sequences present features intermediate between European and eastern Asian sequences, in several parameters-such as the frequencies of certain nucleotides, the levels of nucleotide diversity, mean pairwise differences, and genetic distances. Several hypotheses could explain the intermediate position of central Asia between Europe and eastern Asia, but the most plausible would involve extensive levels of admixture between Europeans and eastern Asians in central Asia, possibly enhanced during the Silk Road trade and clearly after the eastern and western Eurasian human groups had diverged. Lowland and highland Kirghiz mtDNA sequences are very similar, and the analysis of molecular variance has revealed that the fraction of mitochondrial genetic variance due to altitude is not significantly different from zero. Thus, it seems unlikely that altitude has exerted a major selective pressure on mitochondrial genes in central Asian populations.
316 citations
TL;DR: This paper argued that it is hardly the case that the profession is fully aware that the application of different filters to the data leads to different outcomes and that we have enough evidence to claim that these differences are unimportant to evaluate the fit models to the dataset.
219 citations
TL;DR: In this paper, the authors studied the generation and transmission of international cycles in a multi-country model with production and consumption interdependencies, and two sources of disturbance were considered and three channels of propagation were compared.
177 citations
TL;DR: There is a significant difference in behavior from period to period whether a player has decided to split the pie before or after the opponent, and behavior is structure according to a simple cognitive process, called learning direction theory.
171 citations
TL;DR: This basic model best illustrates intuition and analysis techniques while still containing the essential features and serving as a prototype for many applications.
Abstract: Classical and recent results in statistical pattern recognition and learning theory are reviewed in a two-class pattern classification setting. This basic model best illustrates intuition and analysis techniques while still containing the essential features and serving as a prototype for many applications. Topics discussed include nearest neighbor, kernel, and histogram methods, Vapnik-Chervonenkis theory, and neural networks. The presentation and the large (though nonexhaustive) list of references is geared to provide a useful overview of this field for both specialists and nonspecialists.
167 citations
TL;DR: Several probabilistic maximal coveringlocation—allocation models with constrained waiting time for queue length are presented to consider service congestion.
Abstract: When dealing with the design of service networks, such as health andemergency medical services, banking or distributed ticket-selling services, the location of servicecenters has a strong influence on the congestion at each of them, and, consequently, on thequality of service. In this paper, several probabilistic maximal coveringlocation—allocation models with constrained waiting time for queue length are presentedto consider service congestion. The first model considers the location of a given number ofsingle-server centers such that the maximum population is served within a standard distance, andnobody stands in line for longer than a given time or with more than a predetermined number ofother users. Several maximal coverage models are then formulated with one or more servers perservice center. A new heuristic is developed to solve the models and tested in a 30-node network.
159 citations
TL;DR: The authors examined the role played by cyclically-moving factor shares in the US income distribution by analyzing four heterogeneous household extensions of the neoclassical growth model and concluded that partitioning the population into five types subject to type-specific employment processes seems to be enough to account for most aspects of income distribution business cycle dynamics.
148 citations
TL;DR: A discrete location model formulation is presented to address the issue of locating new facilities when there is uncertainty in demand, travel times or distance and is applied to the location of fire stations in Barcelona.
142 citations
TL;DR: In this paper, the authors compare the two main types of payment systems, gross and net, in a framework where uncertainty arises from several sources: the time of consumption, the location of consumption and the return on investment.
140 citations
TL;DR: In this paper, it was shown that while presupposition may play a role in accounting for the so-called definiteness restriction associated with the construction, presupposition cannot account for all of the facts that cannot be explained by a single generalization.
Abstract: The analysis to be proposed has two notable consequences. First, it indicates that while presupposition may play a role in accounting for the so-called definiteness restriction associated with the construction, presupposition cannot account for all of the definiteness restriction facts-in fact, on the view defended here, the definiteness restriction facts cannot be explained by a single generalization. Second, it supports the view that the notions weak and strong should be redefined as suggested in Ladusaw 1994, where “weak” is essentially equated with “nonparticular-denoting”.
01 Sep 1998
TL;DR: The problem of generating expressive musical performances in the context of tenor saxophone interpretations was studied and SaxEx applies the inferred expressive transformations to the new phrase using the synthesis capabilities of Sms.
Abstract: The problem of generating expressive musical performances in the context of tenor saxophone interpretations was studied. Several recordings of a tenor sax playing different Jazz ballads with different degrees of expressiveness including an inexpressive interpretation of each ballad were made. These recordings were analyzed, using Sms spectral modeling techniques, to extract information related to several expressive parameters. This set of parameters and the scores constitute the set of cases (examples) of a case‐based system. From this set of cases, the system infers a set of possible expressive transformations for a given new phrase applying similarity criteria, based on background musical knowledge, between this new phrase and the set of cases. Finally, SaxEx applies the inferred expressive transformations to the new phrase using the synthesis capabilities of Sms.
TL;DR: In this paper, the authors study the evolution of sectoral employment and labor cost in eleven European countries in the last two decades and find that sectoral effects account for more than 80% of the long-run differentials across countries and industries in employment growth, whereas countryspecific effects are more important in the analysis of labor cost dynamics.
TL;DR: Journal articles described in press releases, in particular those described first or second in the press release, are associated with the subsequent publication of newspaper stories on the same topic.
Abstract: Context.—Scientific journals issue press releases to disseminate scientific news
about articles they publish.Objective.—To assess whether press releases about journal articles were associated
with publication of subsequent newspaper stories.Design.—Retrospective content analysis of newspaper stories, journal press releases,
and journal tables of contents. From December 1, 1996, to February 28, 1997,
press releases and tables of contents were collected from BMJ, Nature, Science,
and The Lancet, along with newspaper stories on scientific
research published in The New York Times (United
States), Le Figaro and Le Monde (France), El Pais and La Vanguardia (Spain), La Repubblica (Italy),
and the International Herald Tribune.Main Outcome Measurements.—Number of newspaper stories that contained reference to articles appearing
in the 4 scientific journals, number of newspaper stories that referred to
journal articles described in press releases, and the order in which journal
articles were mentioned in press releases.Results.—Of the 1060 newspaper stories analyzed, 142 referred to journal articles;
of these, 119 (84%) referred to articles mentioned in press releases and 23
(16%) referred to journal articles not mentioned in press releases (comparison
of proportions, P =.03). Articles described first
or second were referenced in more newspapers than articles described later
in the press release (P=.01 by χ2
analysis).Conclusions.—Journal articles described in press releases, in particular those described
first or second in the press release, are associated with the subsequent publication
of newspaper stories on the same topic.
TL;DR: In this article, the authors discuss theoretical and empirical work on the interactions between growth and business cycles and distinguish two very different types of approaches to the problem of the influence of macroeconomic fluctuations on long-run growth.
Abstract: This paper discusses recent theoretical and empirical work on the interactions between growth and business cycles. One may distinguish two very different types of approaches to the problem of the influence of macroeconomic fluctuations on long-run growth. In the first type of approach, which relies on learning by doing mechanisms or aggregate demand externalities, productivity growth and direct production activities are complements. An expansion therefore has a positive long-run effect on total factor productivity. In the second type of approach, hereafter labeled 'opportunity cost or 'learning-by-doing', productivity growth and production activities are substitutes. The opportunity cost of some productivity improving activities falls in a recession, which has a long-run positive impact on output. This does not mean, however, that recessions should on average last longer or be more frequent, since the expectation of future recessions reduces today's incentives for productivity growth. We also briefly discuss some empirical work which is mildly supportive of the opportunity cost approach, while showing that it can be reconciled with the observed pro-cyclical behavior of measured total factor productivity. We also describe some theoretical work on the effects of growth on business cycles.
TL;DR: In this paper, the authors investigated the characteristics of the optimal premium schedule and showed that it is not fairly priced: instead it entails subsidization of the less efficient banks by the most efficient ones.
TL;DR: In this paper, the singularity of Minkowski's function is proved in two ways: by exhibiting a set of measure one in which?′(x)=0; and again by actually finding a measure one which is mapped onto a setof measure zero and vice versa.
TL;DR: In this article, the authors study equilibria for economies characterized by moral hazard (hidden action), in which the set of contracts marketed in equilibrium is determined by the interaction of financial intermediaries, and prove that whenever equilibrium contracts do not implement the optimal action, intermediaries make positive profits and equilibrium allocations are third best inefficient.
Abstract: This paper studies equilibria for economies characterized by moral hazard (hidden action), in which the set of contracts marketed in equilibrium is determined by the interaction of financial intermediaries. The crucial aspect of the environment that we study is that intermediaries are restricted to trade non-exclusive contracts: the agents' contractual relationships with competing intermediaries cannot be monitored (or are not contractible upon). We fully characterize equilibrium allocations and contracts. In this set-up equilibrium allocations are clearly incentive constrained inefficient. A robust property of equilibria with non-exclusivity is that the contracts issued in equilibrium do not implement the optimal action. Moreover we prove that, whenever equilibrium contracts do implement the optimal action, intermediaries make positive profits and equilibrium allocations are third best inefficient (where the definition of third best efficiency accounts for constraints which capture the non-exclusivity of contracts).
TL;DR: An extended version of Data Envelopment Analysis is used to obtain measures of technical efficiency in the treatment of critical care patients in intensive care units in Catalonia in 1991-92 and a loglinear regression model is applied to test a number of hypothesis about the role of different environmental factors to explain differences in the efficiency scores.
Abstract: SUMMARY The purpose of this paper is to obtain empirical measures of performance in the management of critical patients treated in intensive care units (ICUs) and to evaluate the factors associated with performance, in a two stage approach. In the first stage, this paper uses an extended version of Data Envelopment Analysis (non-discretionary and categorical variables, and weight constraints under consideration) to obtain measures of technical efficiency in the treatment of 993 critical care patients in intensive care units in Catalonia (Spain) in 1991‐92. The model incorporates accurate individual measures of illness severity from Mortality Probability Models (MPM II0) and quality outcome measures in the input‐output set to obtain non-biased efficiency measures. In the second stage, a loglinear regression model is applied to test a number of hypothesis about the role of different environmental factors—such as ownership, market structure, dimension, internal organization, diagnostic, mortality risk, etc.—to explain differences in the efficiency scores. © 1998 John Wiley & Sons, Ltd.
TL;DR: It is demonstrated that DACIII is able to fully bootstrap itself from a mode of control which solely relies on proximal sensors and predefined reflexes, to a level of controlWhich is dominated by acquired representations of events transduced by distal sensors.
01 Jan 1998
TL;DR: This article used the notion of categorical and thetic utterances to classify utterances as categorical or thetic, i.e., sentences used to represent a thetic judgment.
Abstract: One popular way1 of classifying utterances involves intuitions about their “topichood,” or basic predicational structure. One often hears the suggestion that some utterances are “about an individual,” or have a clear predicational structure; while others are neutral descriptions of eventualities, or lack a clear predicational structure. I will assume that this basic classification has some reality, and following one line of literature, I will refer to the former type of utterance as categorical, and the latter as thetic (notions originally due to Brentano and Marty; see e.g. Kuroda 1972, 1992; Sasse 1987; Ladusaw 1994). Although these terms originally referred to types of judgments, i.e. cognitive acts, I will also use them to describe the sentence forms and utterances (or statements) that represent these judgment types. Thus, e.g. “thetic sentence” should be understood as shorthand for “sentence used to represent a thetic judgment.”
TL;DR: In this paper, the potential effect of market structure on hospital technical efficiency as a measure of performance controlled by ownership and regulation is examined, which is relevant to provide an evaluation of the potential effects of recommended and initiated deregulation policies in order to promote market reforms in the context of a European National Health Service.
Abstract: In this article we examine the potential effect of market structure on hospital technical efficiency as a measure of performance controlled by ownership and regulation. This study is relevant to provide an evaluation of the potential effects of recommended and initiated deregulation policies in order to promote market reforms in the context of a European National Health Service. Our goal was reached through three main empirical stages. Firstly, using patient origin data from hospitals in the region of Catalonia in 1990, we estimated geographic hospital markets through the Elzinga-Hogarty approach, based on patient flows. Then we measured the market level of concentration using the Herfindahl-Hirschman index. Secondly, technical and scale efficiency scores for each hospital was obtained specifying a Data Envelopment Analysis. According to the data nearly two-thirds of the hospitals operate under the production frontier with an average efficiency score of 0.841. Finally, the determinants of the efficiency scores were investigated using a censored regression model. Special attention was paid to test the hypothesis that there is an efficiency improvement in more competitive markets. The results suggest that the number of competitors in the market contributes positively to technical efficiency and there is some evidence that the differences in efficiency scores are attributed to several environmental factors such as ownership, market structure and regulation effects.
TL;DR: In this article, the authors developed a simple monetary model to study the effects of tax evasion on the optimal inflation tax and showed that while there are theoretical reasons for positive optimal inflation rates, the effects are quantitatively small, even in countries with large underground sectors.
TL;DR: In this paper, a location and pricing model for a retail firm that wants to enter a spatial market where a competitor firm is already operating as a monopoly with several outlets is considered.
Abstract: In this paper we consider a location and pricing model for a retail firm that wants to enter a spatial market where a competitor firm is already operating as a monopoly with several outlets The entering firm seeks to determine the optimal uniform mill price and its servers' locations that maximize profits given the reaction in price of the competitor firm to its entrance A tabu search procedure is presented to solve the model together with computational experience
TL;DR: The authors examined the effects of Germany's inter-war reparation agreements in the framework of the Keynesian transfer problem and showed that the Young Plan for German reparations after 1929 created an external credit constraint such that no counteracting capital flows could come forth and reparations were fully (or over-) effected.
Abstract: This paper examines the effects of Germany's inter-war reparation agreements in the framework of the Keynesian transfer problem. According to conventional wisdom, with free capital mobility reparation transfers are necessarily under-effected. I argue that while this is true for the Dawes Plan period between 1924 and 1929, the Young Plan for German reparations after 1929 created an external credit constraint such that during the depression, no counteracting capital flows could come forth and reparations were fully (or over-) effected. This is consistent with the socalled Borchardt hypothesis, which claims that stabilisation policy in Germany during the Great Depression was credit constrained and that lack of budgetary discipline during the preceding years was instrumental in creating this constraint. Accounting for the foreign credit restriction created by the Young Plan, Germany's deflationary policies during the slump can be interpreted as the austerity reaction to an imminent foreign debt crisis. The balance of payment stabilisation required by the Young Plan explains most of the decline in German national product during the depression if Keynesian import functions are assumed and suitably parameterised. Simulation of various different transfer profiles suggests that with tighter macroeconomic policies during the Dawes Plan period after 1924, a large part of the income contraction after 1929 could have been avoided. The results imply that both parts of Borchardt's hypothesis hold up even under plainly Keynesian assumptions.
TL;DR: Analysis of the nature of health care provider choice in the case of patient‐initiated contacts in a National Health Service setting where monetary prices are zero and general practitioners act as gatekeepers to publicly financed specialized care indicates that compensating variation per visit is higher than the direct marginal cost of emergency visits.
Abstract: This paper analyzes the nature of health care provider choice in the case of patient-initiated contacts, with special reference to a National Health Service setting, where monetary prices are zero and general practitioners act as gatekeepers to publicly financed specialized care. We focus our attention on the factors that may explain the continuously increasing use of hospital emergency visits as opposed to other provider alternatives. An extended version of a discrete choice model of demand for patient-initiated contacts is presented, allowing for individual and town residence size differences in perceived quality (preferences) between alternative providers and including travel and waiting time as non-monetary costs. Results of a nested multinomial logit model of provider choice are presented. Individual choice between alternatives considers, in a repeated nested structure, self-care, primary care, hospital and clinic emergency services. Welfare implications and income effects are analyzed by computing compensating variations, and by simulating the effects of user fees by levels of income. Results indicate that compensating variation per visit is higher than the direct marginal cost of emergency visits, and consequently, emergency visits do not appear as an inefficient alternative even for non-urgent conditions.
TL;DR: Treatment with vitamin D3 metabolites could induce a long‐standing response of the haematological disturbance in some low‐intermediate risk MDS patients without inducing hypercalcaemia.
Abstract: Myelodysplastic syndromes (MDS) are a group of clonal disturbances with defective cellular differentiation. Vitamin D3 (VD) analogues can act on the differentiation and maturity of different cell lines. We studied the effects of VD on a series of patients with MDS in an open-design trial. Nineteen patients, 12 men and seven women, with MDS were included. Patients were 74.8 +/- 5.6 years (mean +/- SD), seven had refractory anaemia with ringed sideroblasts, five had refractory anaemia, one had refractory anaemia with excess of blasts and six had chronic myelomonocytic leukaemia. All the patients were in a low to intermediate risk group. Mean follow-up period was 26.21 months, range 9-75. Responders were defined as follows: granulocyte or platelet count increase by 50%, or haemoglobin increase of 1.5 g/dl or transfusion needs decrease by 50%. The first five patients received 266 microg of calcifediol three times a week and the other 14 received calcitriol (0.25-0.75 microg/d). Response was observed in 11 patients. In the calcifediol-treated group, one case responded, three were nonresponders, and one showed progression. In the calcitriol group, 10 were responders (two with major response), and four were non-responders. No correlation was observed between baseline levels of vitamin D metabolites and the presence of response. No hypercalcaemia was observed. Treatment with vitamin D3 metabolites could induce a long-standing response of the haematological disturbance in some low-intermediate risk MDS patients without inducing hypercalcaemia.
01 Jan 1998
TL;DR: Comunicacio presentada a la International Conference on Digital Audio Effects (DAFx), celebrada els dies 19 a 21 de novembre de 1998 a Barcelona, Espanya.
Abstract: Comunicacio presentada a la International Conference on Digital Audio Effects (DAFx), celebrada els dies 19 a 21 de novembre de 1998 a Barcelona, Espanya.
TL;DR: The findings of flunitrazepam-induced euphoria in methadone-maintained subjects together with epidemiological evidence of flunitsodiazepine abuse by opioid dependents, suggest that it may be included in the group of benzodiazepines with a relatively high abuse potential.
Abstract: Abuse liability and acute subjective and psychomotor effects of flunitrazepam were assessed in ten methadone-maintained males with history of benzodiazepine and alcohol use, who voluntarily participated in a double-blind, controlled, cross-over, randomized clinical trial. There were six experimental sessions in which a single oral dose of flunitrazepam 1, 2, and 4 mg; triazolam 0.5 and 0.75 mg; and placebo was given. Evaluations included physiological measures; psychomotor performance tasks (simple reaction time, Digit Symbol Substitution Test, balance task, Maddox-wing device); and self-administered subjective effects questionnaires [Addiction Research Center Inventory (ARCI), Profile of Mood States (POMS), a series of visual analog scales (VAS)]. All drugs but flunitrazepam 1 mg caused an impairment of psychomotor tasks. Effects were more evident with the highest doses of both drugs. Only flunitrazepam 4 mg produced a significant decrease in balance time. Triazolam 0.75 mg induced increases in sedation measured by ARCI-PCAG, depression in POMS, and VAS-drowsiness scores. Flunitrazepam 4 mg caused euphoria-related effects as measured by increases in ARCI-MBG and “high” scores in the VAS. Our findings of flunitrazepam-induced euphoria in methadone-maintained subjects together with epidemiological evidence of flunitrazepam abuse by opioid dependents, suggest that it may be included in the group of benzodiazepines with a relatively high abuse potential.
TL;DR: In this article, the authors investigate the properties of an international real business cycle model with household production and show that a model with disturbances to both market and household technologies reproduces the main regularities of the data and improves existing models in matching international consumption, investment and output correlations without irrealistic assumptions on the structure of international financial markets.