Bayesian prediction of the number of change points in the piecewise linear model

Summary The problem of predicting the number of change points in a piecewise linear model is studied from a Bayesian viewpoint. For a given a priori joint probability functionf _R,C=f_Rf _C/R, whereR is the number of change points andC=C′(R)=(C₁,…,C_R) is the change-point epoch vector, the marginal posterior probability functionf _R.C/Y is obtained, and then used to find predictors forR andC(R).     

Nonparametric kernel density estimation for general grouped data

Interval-grouped data are defined, in general, when the event of interest cannot be directly observed and it is only known to have been occurred within an interval. In this framework, a nonparametric kernel density estimator is proposed and studied. The approach is based on the classical Parzen–Rosenblatt estimator and on the generalisation of the binned kernel density estimator. The asymptotic bias and variance of the proposed estimator are derived under usual assumptions, and the effect of using non-equally spaced grouped data is analysed. Additionally, a plug-in bandwidth selector is proposed. Through a comprehensive simulation study, the behaviour of both the estimator and the plug-in bandwidth selector considering different scenarios of data grouping is shown. An application to real data confirms the simulation results, revealing the good performance of the estimator whenever data are not heavily grouped.     

Transitions to part-time work at older ages: the case of people with disabilities in Europe

This paper analyses the labour-force transitions of older workers with disabilities in general, particularly workers’ transitions to and from part-time employment within a European context. Using the two first waves (2004 and 2007) of the Survey of Health, Ageing and Retirement in Europe, we compare transitions between employment statuses for disabled and non-disabled individuals, even after controlling for different disability trajectories. In addition, we employ a multivariate framework to examine the determinants for remaining in part-time work in 2007 for those individuals who were part-timers in 2004. The results show that older people with long-term disabilities have a higher probability of staying in a part-time job than their compared counterparts. Policy-makers must promote part-time employment as a means of increasing employment opportunities for older workers with disabilities and support gradual retirement opportunities with flexible and reduced working hours.     

A randomized intervention trial to reduce mechanical exposures in the Colombian flower industry

Evidence on the effectiveness of ergonomic interventions to reduce mechanical demands and upper-extremity MSDs is scarce in agriculture. We conducted an intervention to reduce mechanical exposures during manual flower cutting through job rotation, education and reduction of force requirements. One-hundred and twenty workers (20 to 60 years old; 89% women) from six companies that cultivate roses participated in this study. Three companies were randomly assigned to control and intervention groups. We studied changes between baseline and follow-up in self-reported effort and upper-extremity postures, kinematics and muscular activity. Most of the observed changes were moderate for both groups. The intervention group showed differential improvements compared to the control group for the maximum wrist radial deviation and forearm pronation, and acceleration of the forearm supination-pronation and elbow flexion-extension; and the muscular activity of the flexor and extensor carpi radialis and the flexor carpi ulnaris. However, we also observed that the maximum ulnar deviation, velocity of the wrist flexion-extension and muscular activity of the extensor carpi ulnaris improved more in the control group. These mixed results may be related to limited time for intervention adjustment, and uncontrolled task changes in the control group. Future research should address these issues and test other solutions.     

Prevalence of discomfort/pain complaints and related factors in dental professionals of the public health service in Araucária, Paraná state, Brazil

This poster presents a study about the influence of gender related factors, age, body weight, time of service in the profession and practice of physical exercise on the prevalence of discomfort/pain complaints in dental professionals. The scope of this study was limited to 123 subjects, 84.24% of professionals in the public dental clinics, who answered the multidimensional analytical work questionnaire. The data suggest that the lack postural awareness can contribute to the maintenance of painful conditions and also the low commitment to self-care can perpetuate the state of musculoskeletal discomfort/pain, justifying the application of the ergonomics concepts in the workplace and systematic guidance to professionals to adopt a healthy lifestyle.     

Ergonomics and accessibility for people with visual impairment in hotels

This article presents a diagnosis of luxury or superior hotels in the city of Natal, located in the state of Rio Grande do Norte, in northeastern Brazil, in what concerns accessibility to the visually impaired. The main objective is to present the guiding principles to design actions and interventions that must be considered in the preparation or revision of technical standards and manuals of good practice in accessibility related to people with visual impairments who are hotel users. The survey showed that the hotels do not meet the normative indications of accessibility, their facilities are in-accessible (have prevented access) or of reduced accessibility and its employees are not prepared to provide adequate hospital services for people with visual impairment. It was concluded that some of the accessibility problems faced by people with visual impairments are also faced by people in general.     

Nesting patterns among Neotropical species assemblages: can reserves in urban areas be failing to protect anurans?

Nestedness among species assemblages implies that sites of lower species richness are subsets of richer sites in a regional species pool. This nestedness is a reflection of a non-random process of species loss as a consequence of factors that promote the disaggregation of assemblages. The impoverishment of assemblage diversity is more often observed in fragmented landscapes. This non-random process has important implications for conservation. We recorded 95 species of anurans across 22 protected areas, of which 11 sites were in an urban matrix and 11 were in a non-urban matrix. We found that sites in the urban matrix had lower richness and high values of nestedness with no spatial autocorrelation among geographic distances and species composition. Thus, species were non-randomly distributed across the landscape and a nested pattern was documented from non-urban matrix sites to urban matrix sites. The impoverishment of assemblages toward the urban matrix sites may suggest that protected areas in an urban matrix are less suitable for anuran conservation than those in a non-urban matrix sites. Both the ecological revitalization of protected areas in urban matrix and protection of non-urban forested sites are needed for the conservation of Neotropical anurans.     

The interplay of spatial diffusion and marital assimilation of Mexicans in the United States, 1980–2011

Recent trends suggest a decline in the rate of intermarriage between Mexicans and non-Hispanic whites. In this paper, we argue that interpretations of this trend as a decline in preferences for intermarriage are misleading because of the lack of adequate data that captures both spatial and temporal variation in the level of intergroup contact. Using data from the Decennial Census (1980–2000) and the American Community Survey (2008–2011), we employ a novel methodological approach to disentangle the impact of spatial diffusion, ethnic replenishment, and shifts in preferences for homophily on Mexican ethnic intermarriage patterns across 543 Consistent Public Use Microdata Areas (c-PUMA). Once changes in the demographic composition of c-PUMAs are accounted for, multilevel models for repeated cross-sectional data provide no evidence of a change in the marital preferences of Mexicans over time. Trends in intermarriage rates are predominantly explained by compositional and structural changes.