Modeling nonlinear time series with local mixtures of generalized linear models

The authors consider a novel class of nonlinear time series models based on local mixtures of regressions of exponential family models, where the covariates include functions of lags of the dependent variable. They give conditions to guarantee consistency of the maximum likelihood estimator for correctly specified models, with stationary and nonstationary predictors. They show that consistency of the maximum likelihood estimator still holds under model misspecification. They also provide probabilistic results for the proposed model when the vector of predictors contains only lags of transformations of the modeled time series. They illustrate the consistency of the maximum likelihood estimator and the probabilistic properties via Monte Carlo simulations. Finally, they present an application using real data.     

Regional trends in fertility and mortality in Brazil

Abstract Questions asked in the 1970 Brazilian census allow the application of fertility and childhood mortality techniques developed by W. Brass. Using some propositions based on fertility estimates from the 1970 census data it was possible to extend the analysis to the 1940, 1950 and 1960 censuses. Estimates are also provided for ten Brazilian regions, for 1940, 1950 and 1970. These estimates show a slight decrease in the fertility level for the country as a whole, but two different trends at regional levels. Between 1940-50 and 1960-70 the poorer regions experienced constant or increasing fertility levels while developed regions experienced declining ones, with only one exception. The mortality estimates indicate a consistent decline in the mortality level of all regions, but also a divergent trend between poor and developed regions, in life expectancies at birth. This work is a summarized version of Chapters II, III and IV of my Ph.D. thesis written under the supervision of Professor D. V. Glass and Mr J. Hobcraft at the University of London. I am most grateful to my supervisors as well as to Professor W. Brass for valuable comments on several aspects of the thesis. While carrying out this study, the author was supported by grants from the Federal University of Minas Gerais, Brazil, and the Ford Foundation.     

Estimation of cost allocation coefficients at the farm level using an entropy approach

This paper aims to estimate the farm cost allocation coefficients from whole-farm input costs. An entropy approach was developed under a Tobit formulation and was applied to a sample of farms from the 2004 Farm Accountancy Data Network data base for Alentejo region, Southern Portugal. A Generalized Maximum Entropy model and Cross Generalized Entropy model were developed to the sample conditions and were tested. Model results were assessed in terms of their precision and estimation power and were compared with the observed data. The entropy approach showed to be a flexible and valid tool to estimate incomplete information, namely regarding farm costs.     

Quantifying the Third Sector in Portugal: An Overview and Evolution from 1997 to 2007

This article presents a global overview of the third sector in Portugal drawing on data from a linked employer–employee database—“Quadros de Pessoal,” which is based on a compulsory annual inquiry to organizations, making it a better source of information than those based on sample surveys and estimates. This study advances on previous overviews by providing more updated numbers for organization size, age, gross revenue and employment levels, as well as their distribution across the ICNPO third sector activity classification. The evolution of these variables from the period 1997 to 2007 is also analyzed. The Portuguese third sector has been fast growing, with revenues amounting to 5.64% of Portugal’s GDP and employment representing 4% of the country’s employment in 2007. It is mainly composed of very small organizations, with diminutive revenues. Perhaps its most striking features are the uneven distribution of employment and revenue and the strong concentration on social services.     

Reference model for implementing ERP systems: an analytical innovation networks perspective

The process for implementing ERP systems is related with the identification of a large range of variables (organisational goals, business rules, business processes, actors, resources and specifics and unique concepts to support these variables). The main agents related to the implementation are the solution supplier, the customer company and the consulting service. If the implementation process is addressed as an organisational innovation, the question is: How to coordinate the ERP implementation resources from an innovation agents network? In order to answer this question, a reference model is proposed for the formation and management of an innovation agent’s network for ERP implementation. The research method is based on a multi-case study for identifying the requirements and to elaborate the reference model applying a modelling method the Enterprise Knowledge Development (EKD). As results, the reference model in an analytical perspective of innovation networks and their drivers, enables to identify, understand and support the process of implementing ERP systems under the EKD models they are: goals; business rules; business processes; actors and resources; concepts; technical components and requirements.     

Ergonomic and usability analysis on a sample of automobile dashboards

This is a research study based on an analysis which sets out to identify and pinpoint ergonomic and usability problems found in a sample of automobile dashboards. The sample consisted of three dashboards, of three different makes and characterized as being a popular model, an average model and a luxury model. The examination was conducted by observation, with the aid of photography, notes and open interview, questionnaires and performing tasks with users, the bases of which are on the principles laid down by methodologies. From this it was possible to point to the existence of problems such as: complaints about the layout, lighting, colors, available area, difficult access to points of interaction, such as buttons, and the difficult nomenclature of dials. Later, the findings and recommendations presented show the need for a further, deeper study, using more accurate tools, a larger sample of users, and an anthropometric study focused on the dashboard, since reading and understanding it have to be done quickly and accurately, and that more attention be given to the study of automobile dashboards, particularly in the most popular vehicles in order to maintain the standards of usability, and drivers' comfort and safety.     

A method to assess safety and resilience in radiopharmaceuticals production process

Radiopharmaceuticals are radiation-emitting substances used in medicine for radiotherapy and imaging diagnosis. A Research Institute, located in Rio de Janeiro, produces three radiopharmaceuticals: the sodium iodate is used in the diagnosis of thyroid dysfunctions, the meta-iodo-benzylguanidine is used in the diagnosis of cardiac diseases, and the fluordesoxyglucose is used in diagnosis in cardiology, oncology, neurology and neuropsychiatry. This paper presents a method to access safety and resilience in radiopharmaceuticals production processes. The method uses resilience indicators in order to proactively evaluate and manage the safety.     

The ambivalence of the work of the hotel managers: an approach to ergonomics

This article uses the contributions of ergonomics to understand the work performed by hotel managers. The concern to understand the job of managers is something new in the ergonomics and few studies address this issue, especially in what concerns the work of hotel managers and its aspects of performance and health, which is the focus of this article. Through a literature review on the subject, it is sought to understand the managers' work activity, the impacts on their health and their organizational performance, as managers take an ambivalent position in organizations, since they have to deal directly with the demands of upper and lower hierarchies in a context of high competition, organizational changes and user requirements. It is then inferred there is a risk of increased work density for managers, bringing negative consequences to their health and organizational performance. This phenomenon, still poorly covered by ergonomics, contributes to a certain invisibility of the manager's work in society as a whole, when the manager may suffer from health problems, which are also common in certain populations of workers who do not take the managerial function.     

The construction of ergonomic demands: application on artisan fishing using jangada fishing rafts in the beach of Ponta Negra

The present article seeks the process of construction of ergonomics demand referring to the artisan fishing activityfound in Ponta Negra beach located in the city of Natal, Brazil. The instruction/construction of demands correspond to the first stage of Work Ergonomic Analysis and allows the understanding of real issues existent in a work situation, rank them and route the providences. The demand presented on this study, features itself as a induced demand, process which some potential demands or hypothetical demands are taken to an organization, after a preview analysis of the work aimed by the study, resulting from a theoretical research (state of the art) and/or from analysis of a reference situation (state of practice), where demands hypothesis are taken in consideration about the pretended work. The demands construction process using interactional methods and techniques, observation methods and techniques and bibliographic research, researches in state of reference or document. This article demonstrates the efficiency of the methodological choice to construct real ergonomic demands and highlights the importance of social construction on that process, which main goal is to refer the ergonomic actions that allow the improvement of work and life conditions for the fishers and sustainability to Jangadeira activity.     

Smoking Risks in Spain: Part II—Perceptions of Environmental Tobacco Smoke Externalities

Previous studies of smoking risk beliefs have focused almost exclusively on risks to the smoker. Using an original set of survey data from Spain, we examine the public's perceived risks from exposures to environmental tobacco smoke. The risk categories considered included lung cancer, heart disease, life expectancy loss, and low birth weight for children of smoking mothers. Risk beliefs were quite high, often dwarfing scientific estimates of the risk. The results are consistent with overestimation of risks from highly publicized, low probability events.