Trend estimation of multivariate time series with controlled smoothness

This paper extends the univariate time series smoothing approach provided by penalized least squares to a multivariate setting, thus allowing for joint estimation of several time series trends. The theoretical results are valid for the general multivariate case, but particular emphasis is placed on the bivariate situation from an applied point of view. The proposal is based on a vector signal-plus-noise representation of the observed data that requires the first two sample moments and specifying only one smoothing constant. A measure of the amount of smoothness of an estimated trend is introduced so that an analyst can set in advance a desired percentage of smoothness to be achieved by the trend estimate. The required smoothing constant is determined by the chosen percentage of smoothness. Closed form expressions for the smoothed estimated vector and its variance-covariance matrix are derived from a straightforward application of generalized least squares, thus providing best linear unbiased estimates for the trends. A detailed algorithm applicable for estimating bivariate time series trends is also presented and justified. The theoretical results are supported by a simulation study and two real applications. One corresponds to Mexican and US macroeconomic data within the context of business cycle analysis, and the other one to environmental data pertaining to a monitored site in Scotland.     

On the performance of Turing's formula: A simulation study

Turing's formula is an amazing result that allows one to estimate the probability of observing something that has not been observed before. After a brief review of the literature, we perform a simulation study to better understand how well this formula works in a variety of situations. We also compare the performance of Turing's formula with several modifications that have appeared in the literature. We find that these modifications tend to outperform Turing's formula, but usually not by very much. We further find that Turing's formula and its modifications tend to work better for heavy-tailed distributions than for light-tailed ones.     

Ergonomic work analysis of airbus pilots job in Brazil

This article is the result of a case study of ergonomic work analysis carried out in a Brazilian airline company, focused on the safety of the activity of Airbus pilots from the company's national lines. The study was divided in three parts, each one with different approach. First step is how critical situations such as accidents and incidents are dealt with during flight. Then it comes to discuss about adversities found in the working place, the airbus cockpit, and the development of risk map. Last but not least, the study focused in how the irregular working journey compromises the biological clock of the pilots end may cause social issues.     

Analysis on the relationship between the school furniture and the work surface lighting and the body posture of public Middle School students from João Pessoa, Paraíba, Brazil

The main objective of this study is to evaluate the impact of school furniture and work surface lighting on the body posture of two public Middle School students from Paraíba (Brazil). The target population included 8th grade groups involving 31 students. Brazilian standards for lighting levels, the CEBRACE standards for furniture measurements and the Postural Assessment Software (SAPO) for the postural misalignment assay were adopted for the measurements comparison. The statistic analysis includes analyses of parametric and non-parametric correlations. The results show that the students' most affected parts of the body were the spine, the regions of the knees and head and neck and about 90% of the students presented postural misalignment. The lighting levels were usually found below 300 lux, below recommended levels. Such results indicate the need of investments in more suitable school furniture and structural reforms aimed at improving the lighting in the classrooms, which could fulfill the students' profile and reduce their complaints.     

Nurses' working tasks and MSDs back symptoms: results from a national survey

Healthcare workers, namely registered nurses (RN), are frequently exposed to work-related musculoskeletal disorders (WRMSDs) risk factors. Identifying the symptoms of these disorders is one of the first epidemiological steps to managing them. This study aims to identify WRMSDs prevalence symptoms in Portuguese RN. During 8 months (2010-2011) the National Public Health School and the Portuguese Registered Nurses Board made a call to all RN to answer an online WRMSDs questionnaire. Respondents (n=2140) are mostly females (77.4%) and work mainly in hospitals (n=1396) and in primary healthcare centers (n=421). Results show high symptoms prevalence (last 12 months) in the lower back (60.6%), the upper back (44.5%), and the neck (48.6%). Nurses' activity, especially patient hygiene in bed, is a strong contributor (p>0.05) to pain in the upper back (OR=1.39 [1.09-1.80]) and lower back (OR=1.4 [1.08-1.84]). Patient holdup without mechanical support has the highest relationship (p>0.05) between work tasks and symptoms in the last 12 months in the upper back (OR=1.50 [1.19-1.90]). Prevalence rates of WRMSDs symptoms in Portuguese nurses are no different from other studies with Swedish, Italian and Greek nurses. Maybe changes in healthcare systems didn't change the way care is delivered and we must rethink how to prevent nurses WRMSDs.     

Father's Migration and Leaving the Parental Home in Rural Mozambique

Migration is an increasingly common global phenomenon and has important implications for the well‐being of family members left behind. Although extensive research has examined the impact of parental labor migration on school‐age children, less is known about its effect on adolescents. In this study, the authors used longitudinal survey data collected in rural Mozambique (N = 515) to assess the association between father's migration and adolescent children's leaving the parental home, an important component of the transition to adulthood. The results showed that father's migration delays home‐leaving for adolescent girls and that these effects are not mediated by school enrollment. The results for boys were inconclusive. The authors also found that remittances and longer durations of paternal migration were negatively associated with the transition out of the home. On the basis of the findings, they argue that father's migration delays girls' marriage.     

A Description of Attachment in Adoptive Parents and Adoptees in Romania During Early Adolescence

This study is an assessment of different components of attachment for a sample of Romanian adoptees and their parents, both who participated in the project (n = 63). Results suggest that various aspects of the parent–child relationship in early adolescence is quite positive from both the adoptee and adoptive parent perspective. However, almost half (46 %) of the adoptees were assessed as having insecure attachment. There are differences between all components of parental attachment and adoptee attachment security. Also, insecure attachment is more likely to occur with less optimal parenting style. Implications for social work practice and research are discussed.     

The Social Structuring of Mental Health over the Adult Life Course: Advancing Theory in the Sociology of Aging

The sociology of aging draws on a broad array of theoretical perspectives from several disciplines, but rarely has it developed its own. We build on past work to advance and empirically test a model of mental health framed in terms of structural theorizing and situated within the life course perspective. Whereas most prior research has been based on cross-sectional data, we utilize four waves of data from a nationally representative sample of American adults (Americans' Changing Lives Study) collected prospectively over a 15-year period and find that education, employment and marital status, as well as their consequences for income and health, effectively explain the increase in depressive symptoms after age 65. We also found significant cohort differences in age trajectories of mental health that were partly explained by historical increases in education. We demonstrate that a purely structural theory can take us far in explaining later life mental health.