A hierarchy of adaptive (X)over-bar control charts

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Escape of particles in a time-dependent potential well

We investigate the escape of an ensemble of noninteracting particles inside an infinite potential box that contains a time-dependent potential well. The dynamics of each particle is described by a two-dimensional nonlinear area-preserving mapping for the variables energy and time, leading to a mixed phase space. The chaotic sea in the phase space surrounds periodic islands and is limited by a set of invariant spanning curves. When a hole is introduced in the energy axis, the histogram of frequency for the escape of particles, which we observe to be scaling invariant, grows rapidly until it reaches a maximum and then decreases toward zero at sufficiently long times. A plot of the survival probability of a particle in the dynamics as function of time is observed to be exponential for short times, reaching a crossover time and turning to a slower-decay regime, due to sticky regions observed in the phase space.

An objective reconstruction of the chain of contagion

North's clustering method, which is based on a much used ecological model, the nearest neighbor distance, was applied to the objective reconstruction of the chain of household-to-household transmission of variola minor (the mild form of smallpox). The discrete within-household outbreaks were considered as points which were ordered in a time sequence using a 10-40 day interval between introduction of the disease into a source household and a receptor household. The closer points in the plane were assumed to have a larger probability of being links of a chain of household-to-household spread of the disease. The five defining distances (Manhattan or city-block distance between presumptive source and receptor dwellings) were 100, 200, 300, 400 and 500 m. The subchain sets obtained with the five defining distances were compared with the subchains empirically reconstructed during the field study of the epidemic through direct investigation of personal contacts of the introductory cases with either introductory or subsequent cases from previously affected households. The criteria of fit of theoretical to empirical clusters were: (a) the number of clustered dwellings and subchains, (b) number of dwellings in a subchain and (c) position of dwellings in a subchain. The defining distance closet to the empirical findings was 200 m, which fully agrees with the travelling habits of the study population. Less close but acceptable approximations were obtained with 100, 300, 400 and 500 m. The latter two distances gave identical results, as if a clustering ceiling had been reached. It seems that North's clustering model may be used for an objective reconstruction of the chain of contagious whose links are discrete within-household outbreaks. © 1984.

Stochastic field processes in the mathematical modelling of damped transmission line vibrations

Wind-excited vibrations in the frequency range of 10 to 50 Hz due to vortex shedding often cause fatigue failures in the cables of overhead transmission lines. Damping devices, such as the Stockbridge dampers, have been in use for a long time for supressing these vibrations. The dampers are conveniently modelled by means of their driving point impedance, measured in the lab over the frequency range under consideration. The cables can be modelled as strings with additional small bending stiffness. The main problem in modelling the vibrations does however lay in the aerodynamic forces, which usually are approximated by the forces acting on a rigid cylinder in planar flow. In the present paper, the wind forces are represented by stochastic processes with arbitrary crosscorrelation in space; the case of a Kármán vortex street on a rigid cylinder in planar flow is contained as a limit case in this approach. The authors believe that this new view of the problem may yield useful results, particularly also concerning the reliability of the lines and the probability of fatigue damages. © 1987.

Image registration and image interpolation in volume rendering of cross sections

We outline a method for registration of images of cross sections using the concepts of The Generalized Hough Transform (GHT). The approach may be useful in situations where automation should be a concern. To overcome known problems of noise of traditional GHT we have implemented a slight modified version of the basic algorithm. The modification consists of eliminating points of no interest in the process before the application of the accumulation step of the algorithm. This procedure minimizes the amount of accumulation points while reducing the probability of appearing of spurious peaks. Also, we apply image warping techniques to interpolate images among cross sections. This is needed where the distance of samples between sections is too large. Then it is suggested that the step of registration with GHT can help the interpolation automation by simplifying the correspondence between points of images. Some results are shown.

Collective scattering of massive stars in higher order gravity

In the weak field approximation of higher order gravity theory a gravitational potential is described by a Newtonian plus a Yukawa-like term. This new term is used to explain some aspects of galactic dynamics, without considering dark matter. Its presence modifies the scattering probability of a massive intruder star and relaxation time of the stellar system.

Economic viability and selection of irrigation systems using simulation and stochastic dominance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Detecting migrants in populations of Rhizoctonia solani anastomosis group 3 from potato in North Carolina using multilocus genotype probabilities

The relative contribution of migration of Rhizoctonia solani anastomosis group 3 (AG-3) on infested potato seed tubers originating from production areas in Canada, Maine, and Wisconsin (source population) to the genetic diversity and structure of populations of R. solani AG-3 in North Carolina (NC) soil (recipient population) was examined. The frequency of alleles detected by multilocus polymerase chain reaction-restriction fragment length polymorphisms, heterozygosity at individual loci, and gametic phase disequilibrium between all pairs of loci were determined for subpopulations of R. solani AG-3 from eight sources of potato seed tubers and from five soils in NC. Analysis of molecular variation revealed little variation between seed source and NC recipient soil populations or between subpopulations within each region. Analysis of population data with a Bayesian-based statistical method previously developed for detecting migration in human populations suggested that six multilocus genotypes from the NC soil population had a statistically significant probability of being migrants from the northern source population. The one-way (unidirectional) migration of genotypes of R. solani AG-3 into NC on infested potato seed tubers from Canada, Maine, and Wisconsin provides a plausible explanation for the lack of genetic subdivision (differentiation) between populations of the pathogen in NC soils or between the northern source and the NC recipient soil populations.

Pancreatic β-cell defects in women at risk of type 2 diabetes

We evaluated insulin release and insulin sensitivity in women with basal and/or postprandial hyperglycemia but normal oral glucose tolerance test (OGTT) in previous pregnancy (GHG). These women were individually matched with females without previous hyperglycemia (NGT). Both groups consisted of normal glucose-tolerant women at the time of this study. They underwent OGTT (75g; n= 32 pairs) and hyperglycemic clamp experiments (10mmoll-1; n=27 pairs) with plasma glucose, insulin, and C-peptide measurements and calculation of insulinogenic index, first- and second-phase insulin release, and insulin sensitivity index (ISI). The GHG group showed higher glycosylated hemoglobin levels (6.2±0.6% versus 5.8±0.8%; P<0.05); lower insulinogenic index at 30min (134.03±62.69pmolmmol-1 versus 181.59±70.26pmolmmoll-1; P<0.05) and diminished C-peptide response in relation to glucose (4.05±0.36nmolmmol-1 versus 4.23±0.36nmolmmol-1; P<0.05) at OGTT. Both groups did not show difference in insulin secretion and ISI by hyperglycemic clamp technique. We concluded that in up to 12 years from index pregnancy, women with previous GHG, presenting normal glucose tolerance and well-matched with their controls, showed β-cell dysfunction without change in ISI. As women with previous GHG are at risk of type 2 diabetes, β-cell dysfunction may be its primary defect. © 2003 Elsevier B.V. All rights reserved.

Implantation failures: Success of assisted hatching with quarter-laser zona thinning

Implantation failure after IVF is one of the factors associated with a reduced chance of pregnancy for some patients. Assisted hatching methodologies are designed to facilitate the embryo's escape from the zona pellucida, and this strategy has been suggested as a means of improving pregnancy rates in patients with previous implantation failure. The aim of this prospective and randomized study was to evaluate the efficacy of quarter-laser zona thinning assisted hatching (qLZT-AH) in improving the implantation of embryos in patients with previous implantation failure. A total of 150 patients with a history of previous implantation failure were treated with intracytoplasmic sperm injection, and allocated into two groups: group 1, only one previous implantation failure, and group 2, repeated implantation failures. The patients in each group were randomized at the time of embryo transfer into a control group (no qLZT-AH) or experimental group where qLZT-AH was performed. For patients with repeated implantation failures, the implantation rate in those who received laser-thinned embryos was significantly higher (P=0.02) than in those whose embryos were not laser-thinned (10.9 and 2.6% respectively). However, this difference was not observed in patients who presented with only one previous implantation failure. The data demonstrate that qLZT-AH is an effective strategy for improving the implantation of embryos in patients with repeated implantation failures.

Secretion of middle ear in infants - Occurrence, recurrence and related factors

Objective: The present study aimed at evaluating the occurrence and recurrence of middle ear effusion and possible associated factors in the first two years of life of 190 newborns and infants, participants in the interdisciplinary prevention, detection, and intervention program at the Clínica de Educação para Saúde of Universidade do Sagrado Coração, Methods: Newborns and infants were monthly submitted to anamneses, otoscopy, behavioral hearing assessment using sound instruments and pure tones (pediatric audiometry) and tympanometry. Results: The results revealed that 68.4% of infants presented one or more episodes of middle ear effusion during their two first years, with more recurrence among males. Peak occurrence was between four and 12 months of age and, the earlier the first episode, the higher the probability of recurrence. Greatest incidence was during May and August. It was found that, of the variables investigated, the period of exclusive breastfeeding actuated as a protector factor. With respect of risk factors, it was observed that passive smoking, gastro-esophageal reflux and respiratory allergy were related with the recurrences of effusion. Conclusion: Findings revealed the importance of periodic auditory follow-up for infants during their first two years of life, considered to be the critical period of auditory system maturation, during which sensory deprivation can be responsible for damage to the development of speech, language and other auditory abilities. Copyright © 2005 by Sociedade Brasileira de Pediatria.

Puncture wounds by driftwood catfish during bucket baths: Local habits of riverside people and fish natural history in the Amazon

Objective. - To assess the prevalence of stings by small spiny driftwood catfish (carataí) of the genus Centromochlus (Auchenipteridae) accidentally caught in buckets during bucket bathing by riverside people along the Brazilian Amazon and to determine the probability of catching specimens of these fish during random throws of a bucket into the river. Methods. - We interviewed 27 adult residents living at the confluence of the Negro and Solimões rivers in Brazil regarding whether or not they had ever been stung by driftwood catfish while bucket bathing. To assess the likelihood of catching catfish in bathing buckets, we randomly threw a typical plastic bucket used for bathing in 4 series of 10 throws into the river at dusk or night around a floating house. Results. - Seventeen of the 27 subjects (63%) reported being injured by driftwood catfish during bucket bathing. Three individuals (17.6%) had been injured 2 to 3 times, totaling 23 puncture accidents. All stings occurred at dusk or early night. In the 4 series of 10 bucket throws, we caught 3 driftwood catfish (in 1 series we did not catch any fish). Thus, the chance of catching a driftwood catfish in a single bucket throw at dusk was slightly less than 10%. Conclusions. - The prevalence of stings by driftwood catfish to people bucket bathing in this section of the Brazilian Amazon is high, partly because of the relatively high chances of catching these small catfish during random throws of a bathing bucket into the river.

Relationship between gingival clinical parameters and the reactivity of the BANA test in subgingival samples from children.

Gingivitis is the first manifestation of periodontal disease, and is characterized by painless and slow evolution. Early diagnosis and intervention must be done to avoid the possibility of precocious periodontitis during the childhood or teenage years. The enzymatic BANA test (N-benzoyl-DL-arginine-naphthylamide) was used to evaluate subgingival samples from 54 children between 6 and 9 years of age. Plaque index (PI) and gingival index (GI) were assessed according to the criteria recommended by Löe (1967). Subgingival plaque was collected from the region that featured the greatest periodontal alteration, represented by a higher gingival index. Resulting data were grouped individually according to visible and non-visible plaque and bleeding and non-bleeding gingiva. Results showed that there was no statistically significant correlation between the presence of visible plaque and the positivity of the BANA test, nor was there a statistically significant correlation between the presence of bleeding and the positivity of the BANA test in subgingival samples obtained from children. This study concluded that the BANA test is not an ideal diagnostic test to be applied to children.

Transtorno bipolar do humor e gênero

Although the bipolar disorder (BD) occurs almost with the same frequency in both genders, the phenomenology and the outcome of the illness differ between them. Nevertheless, there is evidence that women with BD show, more than men, delayed beginning, especially in their fifth decade, more rapid cycling outcome, more depressive episodes, more dysphoric mania, more mixed states and more BD type II. Even so, the findings are not always consistent. Although the risk of comorbidities in BD includes, for both the sorts, excessive alcoholic consumption and drugs, bipolar men would have greater probability of being alcohol dependent, of not seeking treatment and of committing suicide. Suggested hypotheses to explain such differences vary from those centered in cultural or psychological aspects to those that focus on the steroids hormones, and other hormones such as cortisol, thyroid hormones and even on the cerebral anatomy. The reproductive cycle (menstrual cycle, pregnancy and menopause) influences on the BD phenomenology and its relevance to the therapeutical options in the treatment of the BD in women are presented in the last part of this review. Further investigations must to be done in order to clarify this controversy. However, up to now the data indicate that estrogen therapy is not to be primarily indicated to prevent depression, Alzheimer disease or cognition impairment.

Obsessive-compulsive disorder: Influence of age at onset on comorbidity patterns

Purpose: This study investigates the influence of age at onset of OCS on psychiatric comorbidities, and tries to establish a cut-off point for age at onset. Methods: Three hundred and thirty OCD patients were consecutively recruited and interviewed using the following structured interviews: Yale-Brown Obsessive Compulsive Scale; Yale Global Tic Severity Scale and the Structured Clinical Interview for DSM-IV. Data were analyzed with regression and cluster analysis. Results: Lower age at onset was associated with a higher probability of having comorbidity with tic, anxiety, somatoform, eating and impulse-control disorders. Longer illness duration was associated with lower chance of having tics. Female gender was associated with anxiety, eating and impulse-control disorders. Tic disorders were associated with anxiety disorders and attention-deficit/hyperactivity disorder. No cut-off age at onset was found to clearly divide the sample in homogeneous subgroups. However, cluster analyses revealed that differences started to emerge at the age of 10 and were more pronounced at the age of 17, suggesting that these were the best cut-off points on this sample. Conclusions: Age at onset is associated with specific comorbidity patterns in OCD patients. More prominent differences are obtained when analyzing age at onset as an absolute value. © 2008 Elsevier Masson SAS. All rights reserved.