The pareto-stability concept is a natural solution concept for discrete matching markets with indifferences

In a decentralized setting the game-theoretical predictions are that only strong blockings are allowed to rupture the structure of a matching. This paper argues that, under indifferences, also weak blockings should be considered when these blockings come from the grand coalition. This solution concept requires stability plus Pareto optimality. A characterization of the set of Pareto-stable matchings for the roommate and the marriage models is provided in terms of individually rational matchings whose blocking pairs, if any, are formed with unmatched agents. These matchings always exist and give an economic intuition on how blocking can be done by non-trading agents, so that the transactions need not be undone as agents reach the set of stable matchings. Some properties of the Pareto-stable matchings shared by the Marriage and Roommate models are obtained.

Adjusting prices in the multiple-partners assignment game

Starting with an initial price vector, prices are adjusted in order to eliminate the excess demand and at the same time to keep the transfers to the sellers as low as possible. In each step of the auction, to which set of sellers should those transfers be made is the key issue in the description of the algorithm. We assume additively separable utilities and introduce a novel distinction by considering multiple sellers owing multiple identical objects and multiple buyers with an exogenously defined quota, consuming more than one object but at most one unit of a seller`s good and having multi-dimensional payoffs. This distinction induces a necessarily more complicated construction of the over-demanded sets than the constructions of these sets for the other assignment games. For this approach, our mechanism yields the buyer-optimal competitive equilibrium payoff, which equals the buyer-optimal stable payoff. The symmetry of the model allows to getting the seller-optimal stable payoff and the seller-optimal competitive equilibrium payoff can then be also derived.

Fiscal policy and reelection in Brazilian municipalities

This paper uses a new panel of more than 2,000 Brazilian municipalities over 13 years to analyze the influence of public expenditures on the probability of mayors` reelection. We examine Brazilian municipal elections from 1988 to 2000 using a logit fixed-effects model. The results suggest that mayors who spend more during their terms of office increase the probability of their own reelection or of a successor of the same political party. In particular, higher capital spending over the years preceding elections and current expenditures in election years are beneficial to Brazilian incumbent mayors.

Who chooses to inflation target?

In this article, we seek what are the factors behind a country`s decision to move to Inflation Targeting. We find that high past inflation, low debt levels and the absence of a nominal exchange rate anchor increase the probability that a country will end up opting for it. (C) 2007 Elsevier B.V. All rights reserved.

The stability of the equilibrium outcomes in the admission games induced by stable matching rules

A stable matching rule is used as the outcome function for the Admission game where colleges behave straightforwardly and the students` strategies are given by their preferences over the colleges. We show that the college-optimal stable matching rule implements the set of stable matchings via the Nash equilibrium (NE) concept. For any other stable matching rule the strategic behavior of the students may lead to outcomes that are not stable under the true preferences. We then introduce uncertainty about the matching selected and prove that the natural solution concept is that of NE in the strong sense. A general result shows that the random stable matching rule, as well as any stable matching rule, implements the set of stable matchings via NE in the strong sense. Precise answers are given to the strategic questions raised.

Multicollinearity and financial constraint in investment decisions: a Bayesian generalized ridge regression

This paper addresses the investment decisions considering the presence of financial constraints of 373 large Brazilian firms from 1997 to 2004, using panel data. A Bayesian econometric model was used considering ridge regression for multicollinearity problems among the variables in the model. Prior distributions are assumed for the parameters, classifying the model into random or fixed effects. We used a Bayesian approach to estimate the parameters, considering normal and Student t distributions for the error and assumed that the initial values for the lagged dependent variable are not fixed, but generated by a random process. The recursive predictive density criterion was used for model comparisons. Twenty models were tested and the results indicated that multicollinearity does influence the value of the estimated parameters. Controlling for capital intensity, financial constraints are found to be more important for capital-intensive firms, probably due to their lower profitability indexes, higher fixed costs and higher degree of property diversification.

Worker demography in a large-colony, swarm-founding wasp

Neotropical swarm-founding wasps build nests enclosed in a covering envelope, which makes it difficult to count individual births and deaths. Thus, knowledge of worker demography is very limited for swarm-founding species compared with that for independent-founding species. In this study, we explored the worker demography of the swarm-founding wasp Polybia paulista, the colony size of which usually exceeds several thousand adults. We considered each wasp colony as an open-population and estimated the survival probability, recruitment rate, and population size of workers using the developments of the Cormack-Jolly-Seber model. We found that capture probability varied considerably among the workers, probably due to age polyethism and/or task specialization. The daily survival rate of workers was high (around 0.97) throughout the season and was not related to the phase of colony development. On the other hand, the recruitment rate ranged from 0 to 0.37, suggesting that worker production was substantially less important than worker survival in determining worker population fluctuations. When we compared survival rates among worker groups of one colony, the mean daily survival rate was lower for founding workers than for progeny workers and tended to be higher in progeny workers that emerged in winter. These differences in survivorship patterns among worker cohorts would be related to worker foraging activity and/or level of parasitism.

Automated determination of rifampicin in plasma samples by in-tube solid-phase microextraction coupled with liquid chromatography

A sensitive and automated method is described for determination of rifampicin in plasma samples for therapeutic drug monitoring by in-tube solid-phase microextraction coupled with liquid chromatography (in-tube SPME/LC). Important factors in the optimization of in-tube SPME are discussed, such as coating type, sample pH, sample draw/eject volume, number of draw/eject cycles, and draw/eject flow rate. Analyte pre-concentrated in the polyethylene glycol phase was directly transferred to the liquid chromatographic column by percolation of the mobile phase, without carryover. The method was linear over the 0.1-100 mu g/mL range, with a linear coefficient value (r(2)) of 0.998. The inter-assay precision presented coefficient of variation <= 1.7%. The effectiveness and practicability of the proposed method are proven by analysis of plasma samples from ageing patients undergoing therapy with rifampicin. (C) 2011 Elsevier B.V. All rights reserved.

Use of the q-Gaussian mutation in evolutionary algorithms

This paper proposes the use of the q-Gaussian mutation with self-adaptation of the shape of the mutation distribution in evolutionary algorithms. The shape of the q-Gaussian mutation distribution is controlled by a real parameter q. In the proposed method, the real parameter q of the q-Gaussian mutation is encoded in the chromosome of individuals and hence is allowed to evolve during the evolutionary process. In order to test the new mutation operator, evolution strategy and evolutionary programming algorithms with self-adapted q-Gaussian mutation generated from anisotropic and isotropic distributions are presented. The theoretical analysis of the q-Gaussian mutation is also provided. In the experimental study, the q-Gaussian mutation is compared to Gaussian and Cauchy mutations in the optimization of a set of test functions. Experimental results show the efficiency of the proposed method of self-adapting the mutation distribution in evolutionary algorithms.

Myocardial scintigraphy and clinical stratification as predictors of events in renal transplant candidates

Background: We tested the hypothesis that the universal application of myocardial scanning with single-photon emission computed tomography (SPECT) would result in better risk stratification in renal transplant candidates (RTC) compared with SPECT being restricted to patients who, in addition to renal disease, had other clinical risk factors. Methods: RTCs (n=363) underwent SPECT and clinical risk stratification according to the American Society of Transplantation (AST) algorithm and were followed up until a major adverse cardiovascular event (MACE) or death. Results: Of the 363 patients, 79 patients (22%) had an abnormal SPECT scan and 270 (74%) were classified as high risk. Both methods correctly identified patients with increased probability of MACE. However, clinical stratification performed better (sensitivity and negative predictive value 99% and 99% vs. 25% and 87%, respectively). High-risk patients with an abnormal SPECT scan had a modest increased risk of events (log-rank = 0.03; hazard ratio [HR] = 1.37; 95% confidence interval [95% CI], 1.02-1.82). Eighty-six patients underwent coronary angiography, and coronary artery disease (CAD) was found in 60%. High-risk patients with CAD had an increased incidence of events (log-rank = 0.008; HR=3.85; 95% CI, 1.46-13.22), but in those with an abnormal SPECT scan, the incidence of events was not influenced by CAD (log-rank = 0.23). Forty-six patients died. Clinical stratification, but not SPECT, correlated with the probability of death (log-rank = 0.02; HR=3.25; 95% CI, 1.31-10.82). Conclusion: SPECT should be restricted to high-risk patients. Moreover, in contrast to SPECT, the AST algorithm was also useful for predicting death by any cause in RTCs and for selecting patients for invasive coronary testing.

The Absence of Coronary Calcification Does Not Exclude Obstructive Coronary Artery Disease or the Need for Revascularization in Patients Referred for Conventional Coronary Angiography

Objectives This study was designed to evaluate whether the absence of coronary calcium could rule out >= 50% coronary stenosis or the need for revascularization. Background The latest American Heart Association guidelines suggest that a calcium score (CS) of zero might exclude the need for coronary angiography among symptomatic patients. Methods A substudy was made of the CORE64 (Coronary Evaluation Using Multi-Detector Spiral Computed Tomography Angiography Using 64 Detectors) multicenter trial comparing the diagnostic performance of 64-detector computed tomography to conventional angiography. Patients clinically referred for conventional angiography were asked to undergo a CS scan up to 30 days before. Results In all, 291 patients were included, of whom 214 (73%) were male, and the mean age was 59.3 +/- 10.0 years. A total of 14 (5%) patients had low, 218 (75%) had intermediate, and 59 (20%) had high pre-test probability of obstructive coronary artery disease. The overall prevalence of >= 50% stenosis was 56%. A total of 72 patients had CS = 0, among whom 14 (19%) had at least 1 >= 50% stenosis. The overall sensitivity for CS = 0 to predict the absence of >= 50% stenosis was 45%, specificity was 91%, negative predictive value was 68%, and positive predictive value was 81%. Additionally, revascularization was performed in 9 (12.5%) CS = 0 patients within 30 days of the CS. From a total of 383 vessels without any coronary calcification, 47 (12%) presented with >= 50% stenosis; and from a total of 64 totally occluded vessels, 13 (20%) had no calcium. Conclusions The absence of coronary calcification does not exclude obstructive stenosis or the need for revascularization among patients with high enough suspicion of coronary artery disease to be referred for coronary angiography, in contrast with the published recommendations. Total coronary occlusion frequently occurs in the absence of any detectable calcification. (Coronary Evaluation Using Multi-Detector Spiral Computed Tomography Angiography Using 64 Detectors [CORE-64]; NCT00738218) (J Am Coll Cardiol 2010;55:627-34) (C) 2010 by the American College of Cardiology Foundation

The Use of Smell Identification Tests in the Diagnosis of Parkinson`s Disease in Brazil

Smell identification tests may be of routine clinical value in the differential diagnosis of PD but are subject to cultural variation and have not been systematically evaluated in the Brazilian population. We have applied culturally adapted translations of the University of Pennsylvania 40-item smell identification test (UPSIT-40) and the 16-item identification test from Sniffin` Sticks (SS-16) to nondemented Brazilian PD patients and controls. Pearson`s correlation coefficient between the test scores was 0.76 (95% CI 0.70-0.81, n = 204, P < 0.001). To calculate reliability measures for each test we used the diagnosis (either PD or control) as outcome variable for separate logistic regression analyses using the score in the UPSIT-40 or the SS-16 as a covariate. The SS-16 specificity was 89.0% with a sensitivity of 81.1% (106 PD and 118 controls). The UPSIT-40 specificity was 83.5% and its sensitivity 82.1% (95 PD and 109 controls). Regression curves were used to associate an individual`s smell test score with the probability of belonging to the PD, as opposed to the control group. Our data provide support for the use of the UPSIT-40 and SS-16 to help distinguish early PD from controls. (c) 2008 Movement Disorder Society

Anxiety Disorders and Rheumatic Fever: Is There an Association?

Introduction: Findings suggest that obsessive-compulsi e disorder (OCD) and related disorders, referred to as obsessive-compulsive spectrum disorders (OCSDs), are more common in patients with rheumatic fever (RF). Objectives: To determine whether RF or Sydenham`s chorea increases the probability of anxiety disorders in the relatives of individuals with RF with and without SC. Methods: This was a case-Control family study in which 98 probands and 389 first-degree relatives (FDRs) were assessed using structured psychiatric interviews. A Poisson regression model was used to determine whether the presence of any disorder in one family member influences the rate of disorders in the remaining family members. Results: Generalized anxiety disorder (GAD) occurred more frequently in the FDRs of RF probands than in those of control probands (P=.018). The presence of RF,GAD, or separation anxiety disorder in one family member significantly increased the chance of OCSDs in another member of the family.

Search for Chronic Beryllium Disease Among Sarcoidosis Patients in Ontario, Canada

Chronic beryllium disease (CBD) is clinically similar to other granulomatous diseases such as sarcoidosis. It is often misdiagnosed if a thorough occupational history is not taken. When appropriate, a beryllium lymphocyte proliferation tests (BeLPT) need to be performed. We aimed to search for CBD among currently diagnosed pulmonary sarcoidosis patients and to identify the occupations and exposures in Ontario leading to CBD. Questionnaire items included work history and details of possible exposure to beryllium. Participants who provided a history of previous work with metals underwent BeLPTs and an ELISPOT on the basis of having a higher pretest probability of CBD. Among 121 sarcoid patients enrolled, 87 (72%) reported no known previous metal dust or fume exposure, while 34 (28%) had metal exposure, including 17 (14%) with beryllium exposure at work or home. However, none of these 34 who underwent testing had positive test results. Self-reported exposure to beryllium or metals was relatively common in these patients with clinical sarcoidosis, but CBD was not confirmed using blood assays in this population.

The quality of life of patients on the lung transplantation waiting list

Introduction. Lung transplantation (LTx) candidates present incapacitating symptoms related to their mobility and activities of daily living, thereby affecting their work, social and emotional relations, and quality of life (QoL). Objective. To study the QoL of LTx candidates, seeking to identify domains that suffer the greatest impact and verify if there are differences among these impairments according to the original lung disease. Methods. We applied the Short Form-36 questionnaires and St George`s Respiratory Questionnaire (SGRQ). All data were analyzed by one-way analysis of variance and the Kruskal Wallis test for the probability with significance at P < 0.05. Results. Fifty patients were divided into groups of emphysema (n = 16), bronchiectasis (n = 12), idiopathic pulmonary fibrosis (n = 7), and cystic fibrosis (n = 15). The functional capacity, physical aspects, general status, and vitality domains showed average values below 50 points. The cystic fibrosis group showed higher functional capacity scores (46 +/- 23) than the emphysema (12 +/- 13) or idiopathic pulmonary fibrosis cohort (7 5). The limitation caused by pain affected the bronchiectasis more than the cystic fibrosis group (52 +/- 28 vs 81 +/- 25, respectively). The SGRQ scores showed impairment among all groups in all domains with average values over 50. The activities domain shows the highest score value; the emphysema (92 +/- 10) and idiopathic pulmonary fibrosis cohorts (91 +/- 9) were extremely affected compared with the cystic fibrosis (69 +/- 21) and bronchiectasis subjects (79 +/- 16). The impact domain show that subjects with cystic fibrosis were less emotionally affected by the disease. Conclusion. LTx candidates showed great impairment of their QoL due to their health problems, above all in the physical-functional aspects; the cystic fibrosis patients were the least affected by their health status.