Almeida M.S.C.,University of Lisbon |
Almeida M.S.C.,Iscte Instituto Universitario Of Lisbon |
Figueiredo M.,University of Lisbon
IEEE Transactions on Image Processing | Year: 2013
The alternating direction method of multipliers (ADMM) has recently sparked interest as a flexible and efficient optimization tool for inverse problems, namely, image deconvolution and reconstruction under non-smooth convex regularization. ADMM achieves state-of-the-art speed by adopting a divide and conquer strategy, wherein a hard problem is split into simpler, efficiently solvable sub-problems (e.g., using fast Fourier or wavelet transforms, or simple proximity operators). In deconvolution, one of these sub-problems involves a matrix inversion (i.e., solving a linear system), which can be done efficiently (in the discrete Fourier domain) if the observation operator is circulant, i.e., under periodic boundary conditions. This paper extends ADMM-based image deconvolution to the more realistic scenario of unknown boundary, where the observation operator is modeled as the composition of a convolution (with arbitrary boundary conditions) with a spatial mask that keeps only pixels that do not depend on the unknown boundary. The proposed approach also handles, at no extra cost, problems that combine the recovery of missing pixels (i.e., inpainting) with deconvolution. We show that the resulting algorithms inherit the convergence guarantees of ADMM and illustrate its performance on non-periodic deblurring (with and without inpainting of interior pixels) under total-variation and frame-based regularization. © 1992-2012 IEEE.
de Almeida M.A.P.,Iscte Instituto Universitario Of Lisbon
Historia, Ciencias, Saude - Manguinhos | Year: 2014
In severe health crisis like those of 1854- 1856, 1899 and 1918, especially in Porto, where cholera morbus, the bubonic plague, typhus fever, pneumonic influenza and smallpox killed high percentages of the population, the images of the epidemics in the press enable us to identify the scientific knowledge in a country considered peripheral, but which had studies and personnel specialized at the most advanced levels for the time. A database of 6, 700 news items and announcements reveals the medical and pharmaceutical knowledge of the second half of the nineteenth and early twentieth centuries, the way it was transmitted and disclosed to the public and the solutions offered by the health authorities. Hygiene was consistently highlighted in the news and announcements.
Giorgi G.,European University at Rome |
Shoss M.K.,Saint Louis University |
Leon-Perez J.M.,Iscte Instituto Universitario Of Lisbon
International Journal of Stress Management | Year: 2015
The macroeconomic context and crisis management are now becoming salient issues among employees. Low levels of fear about the economic situation and the belief that one is capable of obtaining new employment may enable individuals to maintain mental health and job satisfaction in austere times. The aim of the present study is to investigate the relationship of fear of the economic crisis and nonemployability with job satisfaction and psychological distress, while controlling for demographics factors, stress exposures, and high conflict perceptions. This cross-sectional study was conducted in 3 Italian organizations comprising 679 workers with a response rate of more than 60%. Hierarchical regression analysis showed that, after controlling for demographics, psychological demands, lack of job control, and workplace bullying, low perceived employability and fear of the economic crisis were positively associated with psychological distress and negatively associated with job satisfaction. As an emerging topic of study, it appears that economic stress is an important construct in the nomological network for studying organizational health. The present study complements existing stress theories by suggesting that features of the external environment are relevant and important determinants of psychological distress and job dissatisfaction. © 2015 American Psychological Association.
Estevao T.V.,Iscte Instituto Universitario Of Lisbon
Observatorio | Year: 2014
Surveillance is today a global phenomenon, resulting from an increasingly global society. Widespread phenomenon worldwide is cause and basis of academic study with a view to understanding its applicability in contemporary societies. This paper has as main objective to present and discuss the existing theories of surveillance in Social Sciences, analyze the New Paradigm of Surveillance and its dissemination in the Network Society. In order to contextualize the phenomenon of surveillance are analyzed the concepts of "Power", "Moral Panic" and "Risk Society". Copyright © 2014 (Tiago Vaz Estêvão).
Padma P.,Iscte Instituto Universitario Of Lisbon
Quality Management Journal | Year: 2016
The main objective of this study is to examine the tourist satisfaction levels in Portugal across various segments by comparing tourists' expectations with service performance. This paper applies expectancydisconfirmation theory for this purpose. Data were collected through personal interviews of 221 tourists in Lisbon regarding the importance they attach to attributes of tourism and service delivery. The importance-performance analysis identified gaps between tourists' expectations and actual service performance. Overall, most of the tourists in Lisbon are concerned with safety, cleanliness, and price levels. Though tourist segments have differing needs, male and female tourists seem to have similar perceptions and preferences overall. Both package tourists and domestic tourists are not satisfied with the local food. It is further suggested that the friendliness of the local people and the local food could be highlighted in the tourism promotional campaigns. In the future, data could be collected from other tourist segments based on tourists' age and the purpose of their visit. © 2016, ASQ.