Correlation between pre-treatment quasispecies complexity and treatment outcome in chronic HCV genotype 3a

Pre-treatment HCV quasispecies complexity and diversity may predict response to interferon based anti-viral therapy. The objective of this study was to retrospectively (1) examine temporal changes in quasispecies prior to the start of therapy and (2) investigate extensively quasispecies evolution in a group of 10 chronically infected patients with genotype 3a, treated with pegylated alpha 2a-Interferon and ribavirin. The degree of sequence heterogeneity within the hypervariable region 1 was assessed by analyzing 20-30 individual clones in serial serum samples. Genetic parameters, including amino acid Shannon entropy, Hamming distance and genetic distance were calculated for each sample. Treatment outcome was divided into (1) sustained virological responders (SVR) and (2) treatment failure (TF).Our results indicate, (1) quasispecies complexity and diversity are lower in the SVR group, (2) quasispecies vary temporally and (3) genetic heterogeneity at baseline can be used to predict treatment outcome. We discuss the results from the perspective of replicative homeostasis. We discuss the results from the perspective of replicative homeostasis.

Investigating relative clauses in children with specific language impairment

Background: It is well documented that children with Specific Language Impairment (SLI) experience significant grammatical deficits. While much of the focus in the past has been on their morphosyntactic difficulties, less is known about their acquisition of complex syntactic structures such as relative clauses. The role of memory in language performance has also become increasingly prominent in the literature. Aims: This study aims to investigate the control of an important complex syntactic structure, the relative clause, by school age children with SLI in Ireland, using a newly devised sentence recall task. It also aims to explore the role of verbal and short-termworking memory in the performance of children with SLI on the sentence recall task, using a standardized battery of tests based on Baddeley’s model of working memory. Methods and Procedures: Thirty two children with SLI, thirty two age matched typically developing children (AM-TD) between the ages of 6 and 7,11 years and twenty younger typically developing (YTD) children between 4,7 and 5 years, completed the task. The sentence recall (SR) task included 52 complex sentences and 17 fillers. It included relative clauses that are used in natural discourse and that reflect a developmental hierarchy. The relative clauses were also controlled for length and varied in syntactic complexity, representing the full range of syntactic roles. There were seven different relative clause types attached to either the predicate nominal of a copular clause (Pn), or to the direct object of a transitive clause (Do). Responses were recorded, transcribed and entered into a database for analysis. TheWorkingMemory Test Battery for children (WMTB-C—Pickering & Gathercole, 2001) was administered in order to explore the role of short-term memory and working memory on the children’s performance on the SR task. Outcomes and Results: The children with SLI showed significantly greater difficulty than the AM-TD group and the YTD group. With the exception of the genitive subject clauses, the children with SLI scored significantly higher on all sentences containing a Pn main clause than those containing a transitive main clause. Analysis of error types revealed the frequent production of a different type of relative clause than that presented in the task—with a strong word order preference in the NVN direction indicated for the children with SLI. The SR performance for the children with SLI was most highly correlated with expressive language skills and digit recall. Conclusions and Implications: Children with SLI have significantly greater difficulty with relative clauses than YTD children who are on average two years younger—relative clauses are a delay within a delay. Unlike the YTD children they show a tendency to simplify relative clauses in the noun verb noun (NVN) direction. They show a developmental hierarchy in their production of relative clause constructions and are highly influenced by the frequency distribution of the relative clauses in the ambient language.

Exploration of the relationship between tacit knowledge and software system test complexity

This research has explored the relationship between system test complexity and tacit knowledge. It is proposed as part of this thesis, that the process of system testing (comprising of test planning, test development, test execution, test fault analysis, test measurement, and case management), is directly affected by both complexity associated with the system under test, and also by other sources of complexity, independent of the system under test, but related to the wider process of system testing. While a certain amount of knowledge related to the system under test is inherent, tacit in nature, and therefore difficult to make explicit, it has been found that a significant amount of knowledge relating to these other sources of complexity, can indeed be made explicit. While the importance of explicit knowledge has been reinforced by this research, there has been a lack of evidence to suggest that the availability of tacit knowledge to a test team is of any less importance to the process of system testing, when operating in a traditional software development environment. The sentiment was commonly expressed by participants, that even though a considerable amount of explicit knowledge relating to the system is freely available, that a good deal of knowledge relating to the system under test, which is demanded for effective system testing, is actually tacit in nature (approximately 60% of participants operating in a traditional development environment, and 60% of participants operating in an agile development environment, expressed similar sentiments). To cater for the availability of tacit knowledge relating to the system under test, and indeed, both explicit and tacit knowledge required by system testing in general, an appropriate knowledge management structure needs to be in place. This would appear to be required, irrespective of the employed development methodology.

Complexity as key to designing cognitive-friendly environments for older people

The lived environment is the arena where our cognitive skills, preferences, and attitudes come together to determine our ability to interact with the world. The mechanisms through which lived environments can benefit cognitive health in older age are yet to be fully understood. The existing literature suggests that environments which are perceived as stimulating, usable and aesthetically appealing can improve or facilitate cognitive performance both in young and older age. Importantly, optimal stimulation for cognition seems to depend on experiencing sufficiently stimulating environments while not too challenging. Environmental complexity is an important contributor to determining whether an environment provides such an optimal stimulation. The present paper reviews a selection of studies which have explored complexity in relation to perceptual load, environmental preference and perceived usability to propose a framework which explores direct and indirect environmental influences on cognition, and to understand these influences in relation to aging processes. We identify ways to define complexity at different environmental scales, going from micro low-level perceptual features of scenes, to design qualities of proximal environments (e.g., streets, neighborhoods), to broad geographical areas (i.e., natural vs. urban environments). We propose that studying complexity at these different scales will provide new insight into the design of cognitive-friendly environments.