Estimation of a change point in the hazard rate of Lindley model under right censoring

In this article, we consider a single change point model for a sudden change in the hazard rate of Lindley distribution to model right-censored survival data. We derive the quantile function to generate random numbers from the proposed distribution by using the Lambert function. The maximum likelihood estimation method is used to estimate parameters of the change point model. A simulation study is also carried out to analyze the performance of the estimators. To validate our findings, a dataset on bone marrow transplant for patients of acute lymphoblastic leukemia is analyzed using the proposed model and is compared with the existing exponential single change point model.     

A simplified estimation procedure based on the EM algorithm for the power series cure rate model

The family of power series cure rate models provides a flexible modeling framework for survival data of populations with a cure fraction. In this work, we present a simplified estimation procedure for the maximum likelihood (ML) approach. ML estimates are obtained via the expectation-maximization (EM) algorithm where the expectation step involves computation of the expected number of concurrent causes for each individual. It has the big advantage that the maximization step can be decomposed into separate maximizations of two lower-dimensional functions of the regression and survival distribution parameters, respectively. Two simulation studies are performed: the first to investigate the accuracy of the estimation procedure for different numbers of covariates and the second to compare our proposal with the direct maximization of the observed log-likelihood function. Finally, we illustrate the technique for parameter estimation on a dataset of survival times for patients with malignant melanoma.     

Does Social Connectedness Promote a Greater Sense of Well‐Being in Adolescence Over Time?

This longitudinal study was designed to investigate whether or not social connectedness predicts psychological well‐being over time. Structural equation modeling was used to examine the temporal relations between these constructs assessed yearly for 3 years for a sample of 1,774 10‐ to 15‐year‐olds (at Time 1). Results indicated that global connectedness (i.e., connectedness combined across the domains of family, school, peers, and neighborhood) predicted well‐being, but no reciprocal relation was found. However, reciprocal relations were revealed by analyses that examined connectedness at the domain level, that is, for family and school contexts. The results suggest that youth who reported higher levels of social connectedness at one point in time would subsequently report higher well‐being (i.e., life satisfaction, confidence, positive affect, and aspirations).     

Risk factors, clinical features and outcome of treatment of work related musculoskeletal disorders in on-site clinics among IT companies in India

Workrelated musculoskeletal disorders among the IT professional is a common area of concern worldwide. This study was taken up to analyze the prevalence of risk factors, clinical features and outcome of treatment in onsite clinics in vaious information technology companies in India. Result revealed poor office ergonomics (54%), lack of keyboard tray (25%), lack of mouse tray (35%), lack of foot rest (60%), improper monitor height (80%) were the major self reported risk factors. Major identified MSD were Myofascial Pain Syndrome (49.20%), Thoracic outlet syndrome (25.02%), Fibromyalgia syndrome (8.5%). Majorly affected body regions were neck (64.9%), shoulder (42.1%), lower back (56.5%) and thigh (34.2%). The results were comparable with the literature. Feedback of the participants also revealed most of the participants were well satisfied with SHARAN's protocol.     

A computerized system to monitor resilience indicators in organizations

The concepts developed by resilience engineering allow the understanding and monitoring the functioning of organizations and, particularly, to map the role of human activities, in success or in failure, enabling a better comprehension about how people make decisions in unexpected situations. The capture of information about human activities in the various organization levels gives managers a deeper real-time understanding of what is influencing the people performance, providing awareness of the factors that influence positively or negatively the organizational goals initially projected. The monitoring is important because the correct functioning of complex systems depends on the knowledge that people have to perform their activities and how the system environment provides tools that actually support the human performance. Therefore, organizations should look forward through precursors in operating signals to identify possible problems or solutions in the structure of tasks and activities, safety, quality, schedule, rework, and maintenance. We apply the concepts of resilience engineering to understand the organization by the analysis of cognitive tasks and activities. The aim is the development of a computerized system to monitor human activities to produce indicators to access system resilience. The validation of the approach was made in a real organization and the results show the successful applicability of the system. Based on findings obtained after the experiment of the system in a real organization, and managers and workers opinions, it was possible to show that the use of system provided an anticipated (real-time) perception about how activities are effectively being performed, allowing managers and workers to make decisions more consistent with daily problems, and also to anticipate solutions to cope with unexpected situations.     

Fisheries Trade and Social Development in the Philippine‐Malaysia Maritime Border Zone

Weakly regulated natural‐resource trading activities in the remote borderlands of developing countries are commonly viewed both as a means of improving economic development and as a way of smuggling valuable natural resources. Based on data from the Philippine‐Malaysia maritime border that focus on the trade in high‐value live reef fish, this article points to the need to situate such cross‐border activities more closely within the context of local perspectives and priorities. A locally‐grounded perspective is necessary in order to understand the context of social‐development challenges that mediate both macroeconomic and environmental policy outcomes.     

Size matters: vegetation patch size and surface temperature relationship in foothills cities of northwestern Argentina

Urbanization is one of the most extreme forms of land alteration. Energy fluxes are severely affected and cities tend to have the Urban Heat Island (UHI) phenomenon, although vegetated areas inside cities could have a positive effect in mitigating UHI effect. Our main objective was to analyze the relationship between vegetation characteristics, patch size and land surface temperature (LST) in three urban areas of northwestern Argentina. We selected 38 green spaces of different size distributed in four cities, all located in the eastern foothills of the subtropical mountain forests. We used Landsat TM satellite images to calculate Normalized Difference Vegetation Index (NDVI) and LST. We assessed the net effect of patch size on LST by computing a Difference Temperature Index. At the regional scale, our results showed that vegetation patch size had a direct effect on reducing the LST of the green space. At a local scale, the analysis of the relationship between vegetation on urban green spaces and LST along a gradient of urbanization showed that green spaces with more vegetation tends to reduce LST. The results showed that largest green spaces were between 1.5 and 2.8 °C cooler than the surrounding built. In order to mitigate the UHI effect in cities, larger green spaces appear to be a possible solution.     

Marshall–Olkin bivariate Weibull distributions and processes

In this paper we introduce a new probability model known as type 2 Marshall–Olkin bivariate Weibull distribution as an extension of type 1 Marshall–Olkin bivariate Weibull distribution of Marshall–Olkin (J Am Stat Assoc 62:30–44, 1967). Various properties of the new distribution are considered. Bivariate minification processes with the two types of Weibull distributions as marginals are constructed and their properties are considered. It is shown that the processes are strictly stationary. The unknown parameters of the type 1 process are estimated and their properties are discussed. Some numerical results of the estimates are also given.     

Perseverance and passion for achieving long-term goals: transcultural adaptation and validation of the Grit-S scale / Perseverancia y pasión por la consecución de objetivos a largo plazo: adaptación transcultural y validación de la escala Grit-S

The objective of this study was to undertake the transcultural adaptation and validation of the Short Grit Scale (Grit-S) to measure university students’ levels of perseverance and passion for achieving long-term goals. To accomplish this, the Grit-S scale was linguistically and culturally adapted from English to Spanish via the Translation, Review, Adjudication, Pre-testing and Documentation method. After that, the adapted scale was administered to a convenience sample of 1,129 university students comprised of 29.6% males and 70.4% females with a mean age of 21, and finally, its psychometric properties were analysed and compared to the original version. The results reveal acceptable values for the internal consistency of the total scale (α = .71) and outstanding fit indexes for the proposed two-factor structural model (i.e., Consistency of Interest and Perseverance of Effort) (RMSEA = .041, CFI = .96), and the parameters of transcultural adaptation were similar to those in its original version.