The negative binomial-beta Weibull regression model to predict the cure of prostate cancer

In this article, for the first time, we propose the negative binomial-beta Weibull (BW) regression model for studying the recurrence of prostate cancer and to predict the cure fraction for patients with clinically localized prostate cancer treated by open radical prostatectomy. The cure model considers that a fraction of the survivors are cured of the disease. The survival function for the population of patients can be modeled by a cure parametric model using the BW distribution. We derive an explicit expansion for the moments of the recurrence time distribution for the uncured individuals. The proposed distribution can be used to model survival data when the hazard rate function is increasing, decreasing, unimodal and bathtub shaped. Another advantage is that the proposed model includes as special sub-models some of the well-known cure rate models discussed in the literature. We derive the appropriate matrices for assessing local influence on the parameter estimates under different perturbation schemes. We analyze a real data set for localized prostate cancer patients after open radical prostatectomy.

Atividade de comunicação e de trabalho

Este artigo discute o binômio comunicação e trabalho a partir da perspectiva da ergologia, ou seja, da atividade humana. Faz uma breve retrospectiva das teorias de comunicação, analisando como as correntes teóricas hegemônicas vêem de maneira limitada os processos de comunicação. E discute sobre os conceitos de comunicação e de trabalho, propondo uma abordagem de pesquisa que permita melhor compreender esse binômio.

Environmental suitability of a highly fragmented and heterogeneous landscape for forest bird species in south-eastern Brazil

Assessment of the suitability of anthropogenic landscapes for wildlife species is crucial for setting priorities for biodiversity conservation. This study aimed to analyse the environmental suitability of a highly fragmented region of the Brazilian Atlantic Forest, one of the world's 25 recognized biodiversity hotspots, for forest bird species. Eight forest bird species were selected for the analyses, based on point counts (n = 122) conducted in April-September 2006 and January-March 2009. Six additional variables (landscape diversity, distance from forest and streams, aspect, elevation and slope) were modelled in Maxent for (1) actual and (2) simulated land cover, based on the forest expansion required by existing Brazilian forest legislation. Models were evaluated by bootstrap or jackknife methods and their performance was assessed by AUC, omission error, binomial probability or p value. All predictive models were statistically significant, with high AUC values and low omission errors. A small proportion of the actual landscape (24.41 +/- 6.31%) was suitable for forest bird species. The simulated landscapes lead to an increase of c. 30% in total suitable areas. In average, models predicted a small increase (23.69 +/- 6.95%) in the area of suitable native forest for bird species. Being close to forest increased the environmental suitability of landscapes for all bird species; landscape diversity was also a significant factor for some species. In conclusion, this study demonstrates that species distribution modelling (SDM) successfully predicted bird distribution across a heterogeneous landscape at fine spatial resolution, as all models were biologically relevant and statistically significant. The use of landscape variables as predictors contributed significantly to the results, particularly for species distributions over small extents and at fine scales. This is the first study to evaluate the environmental suitability of the remaining Brazilian Atlantic Forest for bird species in an agricultural landscape, and provides important additional data for regional environmental planning.

Bivariate gamma-geometric law and its induced Levy process

In this article we introduce a three-parameter extension of the bivariate exponential-geometric (BEG) law (Kozubowski and Panorska, 2005) [4]. We refer to this new distribution as the bivariate gamma-geometric (BGG) law. A bivariate random vector (X, N) follows the BGG law if N has geometric distribution and X may be represented (in law) as a sum of N independent and identically distributed gamma variables, where these variables are independent of N. Statistical properties such as moment generation and characteristic functions, moments and a variance-covariance matrix are provided. The marginal and conditional laws are also studied. We show that BBG distribution is infinitely divisible, just as the BEG model is. Further, we provide alternative representations for the BGG distribution and show that it enjoys a geometric stability property. Maximum likelihood estimation and inference are discussed and a reparametrization is proposed in order to obtain orthogonality of the parameters. We present an application to a real data set where our model provides a better fit than the BEG model. Our bivariate distribution induces a bivariate Levy process with correlated gamma and negative binomial processes, which extends the bivariate Levy motion proposed by Kozubowski et al. (2008) [6]. The marginals of our Levy motion are a mixture of gamma and negative binomial processes and we named it BMixGNB motion. Basic properties such as stochastic self-similarity and the covariance matrix of the process are presented. The bivariate distribution at fixed time of our BMixGNB process is also studied and some results are derived, including a discussion about maximum likelihood estimation and inference. (C) 2012 Elsevier Inc. All rights reserved.

Homicide and public security indicator trends in the city of Sao Paulo between 1996 and 2008: a time-series ecological study

The scope of this paper was to analyze the association between homicides and public security indicators in Sao Paulo between 1996 and 2008, after monitoring the unemployment rate and the proportion of youths in the population. A time-series ecological study for 1996 and 2008 was conducted with Sao Paulo as the unit of analysis. Dependent variable: number of deaths by homicide per year. Main independent variables: arrest-incarceration rate, access to firearms, police activity. Data analysis was conducted using Stata. IC 10.0 software. Simple and multivariate negative binomial regression models were created. Deaths by homicide and arrest-incarceration, as well as police activity were significantly associated in simple regression analysis. Access to firearms was not significantly associated to the reduction in the number of deaths by homicide (p>0,05). After adjustment, the associations with both the public security indicators were not significant. In Sao Paulo the role of public security indicators are less important as explanatory factors for a reduction in homicide rates, after adjustment for unemployment rate and a reduction in the proportion of youths. The results reinforce the importance of socioeconomic and demographic factors for a change in the public security scenario in Sao Paulo.

Prescribed use of methylphenidate hydrochloride and its correlates among Brazilian college students

Background: The prevalence of prescribed use of methylphenidate (MPH) and its correlates are not well-known in Brazil. Objective: To estimate the prevalence of prescribed use of MPH and its correlates in a sample of Brazilian college students. Methods: Twelve-thousand seven hundred and eleven college students filled out a drug use questionnaire. They were divided into two groups based on the lifetime use of MPH: MPH users (MPHU) and MPH non-users (MPHNU). Quasi-binomial regression models were carried out in order to evaluate the correlation among MPHU and other variables. Results: A lifetime use of MPH was reported from 0.9% of college students (MPHU). Being from the Midwest (PR = 4.8, p < 0.01) and South (PR = 5.2, p < 0.05), living in students housing (PR = 5.8, p < 0.001), prescribed use of amphetamines (PR = 8.9, p < 0.001) and benzodiazepines (< 3 weeks: PR = 4.4, p < 0.001; >= 3 weeks: PR = 6.7, p < 0.001), and harmful use of alcohol (PR = 4.0, p < 0.05) were correlated with MPHU. Discussion: The association of alcohol and drug use with prescribed use of MPH among college students suggests the importance of screening drinking patterns and use of other drugs among students with ADHD symptoms. Cesar ELR, et al. / Rev Psiq Clin. 2012; 39(6):183-8

Using the Hard, Randy, and Rittler Test to Evaluate Color Vision in Capuchins (Cebus libidinosus)

The identification of color vision types in primates is fundamental to understanding the evolution and biological function of color perception. The Hard, Randy, and Rittler (HRR) pseudoisochromatic test categorizes human color vision types successfully. Here we provide an experimental setup to employ HRR in a nonhuman primate, the capuchin (Cebus libidinosus), a platyrrhine with polymorphic color vision. The HRR test consists of plates with a matrix composed of gray circles that vary in size and brightness. Differently colored circles form a geometric shape (X, O, or Delta) that is discriminated visually from the gray background pattern. The ability to identify these shapes determines the type of dyschromatopsy (deficiency in color vision). We tested six capuchins in their own cages under natural sunlight. The subjects chose between two HRR plates in each trial: one with the gray pattern only and the other with a colored shape, presented on the left or right side at random. We presented the test 40 times and calculated the 95 % confidence limits for chance performance based on the binomial test. We also genotyped all subjects for exons 3 and 5 of the X-linked opsin genes. The HRR test diagnosed two subjects as protan dichromats (missing or defective L-cone), three as deutan dichromats (missing or defective M-cone), and one female as trichromat. Genetic analysis supported the behavioral data for all subjects. These findings show that the HRR test can be applied to diagnose color vision in nonhuman primates.

The impact of climate on Leptospirosis in Sao Paulo, Brazil

In this work, we correlate the daily number of human leptospirosis cases with several climatic factors. We used a negative binomial model that considers hospital daily admissions due to leptospirosis as the dependent variable, and the climatic variables of daily precipitation pattern, and maximum and minimum temperature as independent variables. We calculated the monthly leptospirosis admission probabilities from the precipitation and maximum temperature variables. The month of February showed the highest probability, although values were also high during the spring months. The month of February also showed the highest number of hospital admissions. Another interesting result is that, for every 20 mm precipitation, there was an average increase of 31.5% in hospital admissions. Additionally, the relative risk of leptospirosis varied from 1.1 to 2.0 when the precipitation varied from 20 to 140 mm.

Need for recovery from work and sleep-related complaints among nursing professionals

The concept of need for recovery from work (NFR) was deduced from the effort recuperation model. In this model work produces costs in terms of effort during the working day. When there is enough time and possibilities to recuperate, a worker will arrive at the next working day with no residual symptoms of previous effort. NFR evaluates work characteristics such as psychosocial demands, professional work hours or schedules. However, sleep may be an important part of the recovery process. The aim of the study was to test the association between sleep-related complaints and NFR. A cross-sectional study was carried out at three hospitals. All females nursing professionals engaged in assistance to patients were invited to participate (N=1,307). Participants answered a questionnaire that included four sleep-related complaints (insomnia, unsatisfactory sleep, sleepiness during work hours and insufficient sleep), work characteristics and NRF scale. Binomial logistic regression analysis showed that all sleep-related complaints are associated with a high need for recovery from work. Those who reported insufficient sleep showed a greater chance of high need for recovery; OR=2.730 (CI 95% 2.074-3.593). These results corroborate the hypothesis that sleep is an important aspect of the recovery process and, therefore, should be thoroughly investigated.

Ecological implications on the aggregation of Amblyomma fuscum (Acari: Ixodidae) on Thrichomys laurentius (Rodentia: Echimyidae), in northeastern Brazil

We investigated the Amblyomma fuscum load on a pullulating wild rodent population and the environmental and biological factors influencing the tick load on the hosts. One hundred and three individuals of Thrichomys laurentius were caught in an Atlantic forest fragment in northeastern Brazil, as part of a longitudinal survey on ticks infesting non-volant small mammals. Ticks (n = 342) were found on 45 individuals and the overall mean intensity of infestation was 7.6 ticks per infested rodent. Ticks were highly aggregated in the host population and the negative binomial distribution model provides a statistically satisfactory fit. The aggregated distribution was influenced by sex and age of the host. The microhabitat preference by T. laurentius probably increases contact opportunities between hosts and aggregated infesting stages of the ticks and represents important clues about the habitat suitability for A. fuscum.

A Poisson mixed model with nonnormal random effect distribution

In this paper, we propose a random intercept Poisson model in which the random effect is assumed to follow a generalized log-gamma (GLG) distribution. This random effect accommodates (or captures) the overdispersion in the counts and induces within-cluster correlation. We derive the first two moments for the marginal distribution as well as the intraclass correlation. Even though numerical integration methods are, in general, required for deriving the marginal models, we obtain the multivariate negative binomial model from a particular parameter setting of the hierarchical model. An iterative process is derived for obtaining the maximum likelihood estimates for the parameters in the multivariate negative binomial model. Residual analysis is proposed and two applications with real data are given for illustration. (C) 2011 Elsevier B.V. All rights reserved.

Bayesian model accounting for within-class biological variability in Serial Analysis of Gene Expression (SAGE)

Abstract Background An important challenge for transcript counting methods such as Serial Analysis of Gene Expression (SAGE), "Digital Northern" or Massively Parallel Signature Sequencing (MPSS), is to carry out statistical analyses that account for the within-class variability, i.e., variability due to the intrinsic biological differences among sampled individuals of the same class, and not only variability due to technical sampling error. Results We introduce a Bayesian model that accounts for the within-class variability by means of mixture distribution. We show that the previously available approaches of aggregation in pools ("pseudo-libraries") and the Beta-Binomial model, are particular cases of the mixture model. We illustrate our method with a brain tumor vs. normal comparison using SAGE data from public databases. We show examples of tags regarded as differentially expressed with high significance if the within-class variability is ignored, but clearly not so significant if one accounts for it. Conclusion Using available information about biological replicates, one can transform a list of candidate transcripts showing differential expression to a more reliable one. Our method is freely available, under GPL/GNU copyleft, through a user friendly web-based on-line tool or as R language scripts at supplemental web-site.

Effectiveness of a multifactorial falls prevention program in community-dwelling older people when compared to usual care: study protocol for a randomised controlled trial (Prevquedas Brazil)

Background Falling in older age is a major public health concern due to its costly and disabling consequences. However very few randomised controlled trials (RCTs) have been conducted in developing countries, in which population ageing is expected to be particularly substantial in coming years. This article describes the design of an RCT to evaluate the effectiveness of a multifactorial falls prevention program in reducing the rate of falls in community-dwelling older people. Methods/design Multicentre parallel-group RCT involving 612 community-dwelling men and women aged 60 years and over, who have fallen at least once in the previous year. Participants will be recruited in multiple settings in Sao Paulo, Brazil and will be randomly allocated to a control group or an intervention group. The usual care control group will undergo a fall risk factor assessment and be referred to their clinicians with the risk assessment report so that individual modifiable risk factors can be managed without any specific guidance. The intervention group will receive a 12-week Multifactorial Falls Prevention Program consisting of: an individualised medical management of modifiable risk factors, a group-based, supervised balance training exercise program plus an unsupervised home-based exercise program, an educational/behavioral intervention. Both groups will receive a leaflet containing general information about fall prevention strategies. Primary outcome measures will be the rate of falls and the proportion of fallers recorded by monthly falls diaries and telephone calls over a 12 month period. Secondary outcomes measures will include risk of falling, fall-related self-efficacy score, measures of balance, mobility and strength, fall-related health services use and independence with daily tasks. Data will be analysed using the intention-to-treat principle.The incidence of falls in the intervention and control groups will be calculated and compared using negative binomial regression analysis. Discussion This study is the first trial to be conducted in Brazil to evaluate the effectiveness of an intervention to prevent falls. If proven to reduce falls this study has the potential to benefit older adults and assist health care practitioners and policy makers to implement and promote effective falls prevention interventions. Trial registration ClinicalTrials.gov (NCT01698580)

Being the mother of a pregnant adolescent: experiences and expectations

OBJECTIVE: To understand the typical actions of the mother during the pregnancy of her teenage daughter. METHODS: Qualitative study, based on the theoretical-methodological framework of social phenomenology of Alfred Schütz. The data were collected in 2009, and the subjects were nine mothers of adolescent primigravidae. RESULTS: The mother of the pregnant adolescent is typified as one that reacts with surprise and disappointment to being notified of the pregnancy and who, subsequently, conforms to the new reality. In reflecting on her own experience of an adolescent mother, she has expectations to support her daughter during the pregnancy and to offer support, so that the course of her life is not impaired as a result of pregnancy. CONCLUSION: Considering the experience and expectations of the mother of the pregnant adolescent, this study could give subsidies to the planning and execution of the care for this binomial, decreasing the distance between the demands made by it and the practice of health professionals.

Evolução dos homicídios e indicadores de segurança pública no Município de São Paulo entre 1996 a 2008: um estudo ecológico de séries temporais

OBJETIVO: analisar a associação entre homicídios e indicadores de segurança pública no MSP entre 1996 e 2008, após controle para taxa de desemprego e proporção de jovens na população. METODOLOGIA: estudo ecológico de série temporal, tendo como unidade de análise o Município de São Paulo (MSP), entre 1996 e 2008. Variável dependente: óbitos por homicídio; variáveis independentes principais: taxa de aprisionamento-encarceramento (TAE), o acesso a armas de fogo (AAF), e a atividade policial (ATP). A análise dos dados foi realizada com o software Stata.IC 10.0. Modelos de regressão binomial negativa simples e multivariados foram construídos. RESULTADOS: A análise univariada demonstrou associação entre óbitos por homicídio e TAE e entre óbitos e ATP. O AAF não se mostrou associado à redução no número de óbitos por homicídios (p > 0,05). Após ajuste houve perda da significância na associação com ambos indicadores de Segurança Pública. CONCLUSÕES: No MSP o papel das ações de segurança pública perdem importância como fatores explicativos para a redução nos níveis de homicídios após controle para taxa de desemprego e redução na proporção de jovens. Os resultados reforçam a importância dos fatores socioeconômicos e demográficos para a mudança no cenário da segurança em São Paulo.