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Of 59 cases of vertebrobasilar junction aneurysms diagnosed and treated from January 1977 to April 1986, 21 (35.5%) saccular aneurysms arose in a fenestration of the proximal basilar artery. Defects of the media at the junctures of the fenestrated segments, as well as the possible presence of turbulent flow at the vertebrobasilar junction, may explain the(More)
BACKGROUND Depigmentation of the substantia nigra (SN) and locus coeruleus (LC) is a conspicuous pathological feature of Parkinson's disease (PD) and is related to the loss of neuromelanin, whose paramagnetic properties result in high signal on specific T1-weighted magnetic resonance imaging (MRI). Recent studies have suggested that neuromelanin decrease in(More)
BACKGROUND AND PURPOSE Magnetic resonance (MR) studies have demonstrated a significant reduction of neuromelanin in the substantia nigra (SN) of Parkinson's disease (PD) patients with high accuracy for differential diagnosis compared to non-PD controls and essential tremor. However, studies state that not knowing how paramagnetic effects of iron influence(More)
This paper addresses the improvement of throughput upper bounds for live and bounded stochastic Petri nets, presented by the authors in previous works. The introduction of a greater amount of structural information, traps and implicit places, allows to improve the bounds using linear programming problems deened on the net structure, on the routing(More)
3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) lyase deficiency is a rare inborn error affecting leucine catabolism and ketogenesis, usually presenting in the neonatal period. Late forms of the disease have been detected in infancy and childhood, but not in adults. We report a case of HMG-CoA lyase deficiency with initial presentation in a 29-year-old(More)
The authors reviewed the diffusion tensor imaging (DTI) and tractography (DTT) of the normal brainstem and cerebellar white matter in normal volunteers, correlating it with structural magnetic resonance (MR) imaging and DTI data obtained in patients evaluated in our institution with movement disorders, including multisystem atrophy (MSA), spinocerebellar(More)
This paper provides empirical evidence on the impact that private participation in infrastructure has had on key macroeconomic variables in a sample of 21 Latin American countries during the 1985-1998 period. Specifically, we look at the effects on GDP per capita, current public expenditures, public investment and private i nvestment, controlling for(More)
This paper shows how relatively standard methodologies can help measure the efficiency gains from reform in the organization of ports infrastructures. It also shows how these measures can be used to promote competition between ports and be built-in incentive driven regulation. The illustration is based on a study of the effects of the 1993 Port reform in(More)