Sexually transmitted disease prevention: adolescents' perceptions of possible side effects

Forty-eight sexually active adolescents participated in an open-ended interview about the possible secondary consequences (side effects) of implementing measures to reduce the risk of contracting a sexually transmitted disease (STD). These adolescents noted 134 different consequences, which were grouped into 15 substantive categories. When four prevention measures (using condoms, being selective about sex partner(s), being monogamous, and abstaining from sexual activity) were analyzed, different patterns of consequences that were salient to these adolescents emerged. The results are discussed in terms of their implications for understanding and improving adolescent decision making about STD prevention.     

Differential diagnosis of a vascular leukoencephalopathy within a CADASIL family: use of skin biopsy electron microscopy study and direct genotypic screening

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a condition caused by mutations of Notch3 gene on chromosome 19. Ultrastructural analysis of skin vessels discloses typical granular osmiophilic material (GOM) within the vascular smooth muscle basal lamina. We describe a CADASIL family in which two members suffering from a vascular leukoencephalopathy were shown to be CADASIL phenocopies: clinical and magnetic resonance imaging (MRI) findings in these two patients were similar to those observed in their affected relatives. However, the skin biopsy performed on one of them did not reveal any GOM in the vascular smooth muscle cells, and the Notch3 mutation present in this family was shown to be absent in these two individuals. We emphasize the role of a direct DNA test for gene mutation to make a differential diagnosis between CADASIL and other forms of vascular leukoencephalopathy.     

Evaluating voluntary risks of injury

Making sound safety decisions requires accurate estimates of the costs of injuries and the benefits of their reduction. These estimates may be produced intuitively by citizens exposed to risk of injury, or formally, for analysts considering alternative safety policies. All such estimates rely on behavioral assumptions, regarding how people perceive and respond to to risks. They also rely on ethical assumptions, regarding how people should respond. The nature and validity of these assumptions are analyzed here, in order to provide a consumer's guide to techniques designed to evaluate risks and devise safety policies.     

Multi-temporal land-cover classification and change analysis with conditional probability networks: the case of Lesvos Island (Greece)

This study uses a series of Landsat images to map the main land-cover types on the Mediterranean island of Lesvos, Greece. We compare a single-year maximum likelihood classification (MLC) with a multi-temporal maximum likelihood classification (MTMLC) approach, with time-series class labels modelled using a first-order hidden Markov model comprising continuous and discrete variables. A rigorous validation scheme shows statistically significant higher accuracy figures for the multi-temporal approach. Land-cover change accuracies were also greatly improved by the proposed methodology: from 46% to 70%. The results show that when only two dates are used, the mapping of land use/cover is unreliable and a large number of the changes identified are due to the individual-year commission and omission errors.