Browsing by Author "Martins, Ana Paula"
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- Clustering of high values in random fieldsPublication . Pereira, L.; Martins, Ana Paula; Ferreira, HelenaThe asymptotic results that underlie applications of extreme random fields often assume that the variables are located on a regular discrete grid, identified with Z2, and that they satisfy stationarity and isotropy conditions. Here we extend the existing theory, concerning the asymptotic behavior of the maximum and the extremal index, to non-stationary and anisotropic random fields, defined over discrete subsets of R2.We show that, under a suitable coordinatewise mixing condition, the maximum may be regarded as the maximum of an approximately independent sequence of submaxima, although there may be high local dependence leading to clustering of high values. Under restrictions on the local path behavior of high values, criteria are given for the existence and value of the spatial extremal index which plays a key role in determining the cluster sizes and quantifying the strength of dependence between exceedances of high levels. The general theory is applied to the class of max-stable random fields, for which the extremal index is obtained as a function of well-known tail dependence measures found in the literature, leading to a simple estimation method for this parameter. The results are illustrated with non-stationary Gaussian and 1-dependent random fields. For the latter, a simulation and estimation study is performed.
- Sexual expression involving people with dementia living in long‐term care facilities: staff's reactionsPublication . Fonseca, Maria Isabel; Almeida, Daniela; Martins, Ana Paula; Cerqueira, Margarida; Villar, Feliciano; Oliveira, José Martinez de; Afonso, Rosa MarinaThis study aims to explore and compare the reaction of long-term care staff towards situations of sexual intercourse in which one or both partners have dementia. Participants were 538 staff members at 28 Portuguese long-term care facilities. Data were collected using a printed questionnaire with seven vignettes with situations related to the sexuality of LTCF residents. In this study, three of these vignettes were analysed with situations in which residents were having relationships in their bedrooms: (1) one male resident and one female resident; (2) two residents with dementia; (3) two residents, one of them with dementia. For each of the vignettes, participants are asked what they think their ‘colleagues’ would do in each vignette, i.e. ‘What do you think most of your colleagues would do?’ The results revealed that when sexual relationships involved both partners living with dementia, the most selected reaction was ‘Comment on what happened with supervision or direction’, which may suggest that the situation was perceived as difficult or problematic. The most restrictive reactions were most often chosen when only one partner had dementia. This study suggests the need to improve and provide training, so that staff have knowledge and strategies that allow people living with dementia to preserve their sexual rights in long-term care facilities.