Learn More
Dissertação apresentada para obtenção do Grau de Doutor em Engenharia do Ambiente, ABSTRACT Genetic algorithms (GAs) have been used to solve difficult optimization problems in a number of fields. One of the advantages of these algorithms is that they operate well even in domains where little is known, thus giving the GA the flavor of a general purpose(More)
Pulsed Arterial Spin Labeling (PASL) techniques potentially allow the absolute, non-invasive quantification of brain per-fusion using Magnetic Resonance Imaging (MRI). This can be achieved by fitting a kinetic model to the data acquired at a number of inversion times (T I). Some model parameters such as the arterial transit time need to be estimated(More)
Prior work has demonstrated the integration of detailed life-cycle assessment into a traditional design modeling process. While a full life-cycle assessment provides insight into a product's potential impact on the environment, it is often too time consuming for analysis during conceptual product design, where ideas are numerous and information is scarce.(More)
In many longitudinal studies, the outcomes recorded on each subject include both a sequence of repeated measurements at pre-specified times and the time at which an event of particular interest occurs: for example, death, recurrence of symptoms or drop out from the study. The event time for each subject may be recorded exactly, interval censored or right(More)
The new clinically available arterial spin labeling (ASL) perfusion imaging sequences present some advantages relatively to the commonly used blood oxygen level-dependent (BOLD) method for functional brain studies using magnetic resonance imaging (MRI). In particular, regional cerebral blood flow (CBF) changes are thought to be more directly related with(More)
Subarachnoid hemorrhage (SAH) is a life-threatening event that most frequently leads to severe disability and death. Its most frequent cause is the rupture of a saccular intracranial aneurysm (IA), which is a blood vessel dilation caused by disease or weakening of the vessel wall. Although the genetic contribution to IA is well established, to date no(More)
PURPOSE To evaluate the reproducibility of estimation of cerebral blood flow (CBF), bolus arrival time (BAT), and arterial blood volume (aBV) from arterial spin labeling (ASL) data acquired at multiple postlabeling delays (PLDs). MATERIALS AND METHODS CBF, BAT, and aBV parameters were estimated from flow-suppressed and nonflow-suppressed multiple-PDL(More)
OBJECTIVE Ambivalence can be understood as a cyclical movement between an emerging narrative novelty-an Innovative Moment (IM)-and a return to a problematically dominant self-narrative. The return implies that the IM, with its potential for change is devalued right after its emergence. Our goal is to test the hypothesis that the probability of the client(More)