1,058 research outputs found

    Attention, predictive learning, and the inverse base-rate effect: Evidence from event-related potentials

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    We report the first electrophysiological investigation of the inverse base-rate effect (IBRE), a robust non-rational bias in predictive learning. In the IBRE, participants learn that one pair of symptoms (AB) predicts a frequently occurring disease, whilst an overlapping pair of symptoms (AC) predicts a rarely occurring disease. Participants subsequently infer that BC predicts the rare disease, a non-rational decision made in opposition to the underlying base rates of the two diseases. Error-driven attention theories of learning state that the IBRE occurs because C attracts more attention than B. On the basis of this account we predicted and observed the occurrence of brain potentials associated with visual attention: a posterior Selection Negativity, and a concurrent anterior Selection Positivity, for C vs. B in a post-training test phase. Error-driven attention theories further predict no Selection Negativity, Selection Positivity or IBRE, for control symptoms matched on frequency to B and C, but for which there was no shared symptom (A) during training. These predictions were also confirmed, and this confirmation discounts alternative explanations of the IBRE based on the relative novelty of B and C. Further, we observed higher response accuracy for B alone than for C alone; this dissociation of response accuracy (B>C) from attentional allocation (C>B) discounts the possibility that the observed attentional difference was caused by the difference in response accuracy

    Prehistoric Subsistence and Settlement on the Upper Savannah River

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    https://scholarcommons.sc.edu/archanth_books/1006/thumbnail.jp

    Emergence of Formative Life on the Atlantic Coast of the Southeast

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    https://scholarcommons.sc.edu/archanth_books/1005/thumbnail.jp

    Archeological Survey of the Trotters Shoals Reservoir Area in South Carolina

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    https://scholarcommons.sc.edu/archanth_books/1137/thumbnail.jp

    Use of antenatal clinic surveillance to assess the effect of sexual behavior on HIV prevalence in young women in Karonga district, Malawi.

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    BACKGROUND: Antenatal clinic (ANC) surveillance is the primary source of HIV prevalence estimates in low-resource settings. In younger women, prevalence approximates incidence. Sexual behavior monitoring to explain HIV distribution and trends is seldom attempted in ANC surveys. We explore the use of marital history in ANC surveillance as a proxy for sexual behavior. METHODS: Five ANC clinics in a rural African district participated in surveillance from 1999 to 2004. Unlinked anonymous HIV testing and marital history interviews (including age at first sex and socioeconomic variables) were conducted. Data on women aged <25 years were analyzed. RESULTS: Inferred sexual exposure before marriage and after first marriage increased the adjusted odds of infection with HIV by more than 0.1 for each year of exposure. Increasing years within a first marriage did not increase HIV risk. After adjusting for age, women in more recent birth cohorts were less likely to be infected. CONCLUSIONS: Marital status is useful behavioral information and can be collected in ANC surveys. Exposure in an ongoing first marriage did not increase the odds of infection with HIV in this age group. HIV prevalence decreased over time in young women. ANC surveillance programs should develop proxy sexual behavior questions, particularly in younger women

    Children as experiencers: increasing engagement, participation and inclusion for young children in the museum

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    This research aimed to evaluate young children’s engagement, participation and inclusion within a city museum by utilising observations and semi structured interviews with children and families. Both groups requested more interactive exhibits, sensory experiences, making and doing activities and role play opportunities. In this article, we argue for increased visibility of children’s ‘intangible heritage’(Brookshaw, 2016) and opportunities for responding which make links with children’s lives contemporarily. We further argue that museums should view children as experiencers rather than learners

    Alpine plants are on the move: Quantifying distribution shifts of Australian alpine plants through time

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    Aim Alpine plant species’ distributions are thought to have been shifting to higher elevations in response to climate change. By moving upslope, species can occupy cooler and more suitable environments as climate change warms their current ranges. Despite evidence of upslope migration in the northern hemisphere, there is limited evidence for elevational shifts in southern hemisphere plants. Our study aimed to determine if alpine plants in Australia have migrated upslope in the last 2 to 6 decades. Location Kosciuszko National Park, NSW, Australia. Methods We collated historic occurrence data for 36 Australian alpine plant species from herbarium specimens and historic field observations and combined these historic data with modern occurrence data collected in the field. Results Eleven of the thirty-six species had shifted upslope in mean elevation and four species showed downslope elevational shifts. The rate of change for upslope shifts varied between 4 and 10 m per year and the rate of change for most downslope shifts was between 4 and 8 m per year, with one species shifting downslope at a high rate of 18 m per year. Additionally, some species showed shifts upward in their upper range edge and/or upward or downward shifts in their lower range edge. Five species also showed range contractions in the difference between their lower and upper range edges over time, while two showed range expansions. We found no significant differences in elevational shifts through time among herbaceous dicotyledons, herbaceous monocotyledons and shrubs. Main Conclusions Plant elevational shifts are occurring rapidly in the Australian alpine zone. This may allow species to persist under climate change. However, if current warming trends continue, several species within the Australian alpine zone will likely run out of suitable habitat within a century

    A conserved amino acid residue critical for product and substrate specificity in plant triterpene synthases

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    Triterpenes are structurally complex plant natural products with numerous medicinal applications. They are synthesized through an origami-like process that involves cyclization of the linear 30 carbon precursor 2,3-oxidosqualene into different triterpene scaffolds. Here, through a forward genetic screen in planta, we identify a conserved amino acid residue that determines product specificity in triterpene synthases from diverse plant species. Mutation of this residue results in a major change in triterpene cyclization, with production of tetracyclic rather than pentacyclic products. The mutated enzymes also use the more highly oxygenated substrate dioxidosqualene in preference to 2,3-oxidosqualene when expressed in yeast. Our discoveries provide new insights into triterpene cyclization, revealing hidden functional diversity within triterpene synthases. They further open up opportunities to engineer novel oxygenated triterpene scaffolds by manipulating the precursor supply
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