3,993 research outputs found

    Associating object names with descriptions of shape that distinguish possible from impossible objects.

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    Five experiments examine the proposal that object names are closely linked torepresentations of global, 3D shape by comparing memory for simple line drawings of structurally possible and impossible novel objects.Objects were rendered impossible through local edge violations to global coherence (cf. Schacter, Cooper, & Delaney, 1990) and supplementary observations confirmed that the sets of possible and impossible objects were matched for their distinctiveness. Employing a test of explicit recognition memory, Experiment 1 confirmed that the possible and impossible objects were equally memorable. Experiments 2–4 demonstrated that adults learn names (single-syllable non-words presented as count nouns, e.g., “This is a dax”) for possible objectsmore easily than for impossible objects, and an item-based analysis showed that this effect was unrelated to either the memorability or the distinctiveness of the individual objects. Experiment 3 indicated that the effects of object possibility on name learning were long term (spanning at least 2months), implying that the cognitive processes being revealed can support the learning of object names in everyday life. Experiment 5 demonstrated that hearing someone else name an object at presentation improves recognition memory for possible objects, but not for impossible objects. Taken together, the results indicate that object names are closely linked to the descriptions of global, 3D shape that can be derived for structurally possible objects but not for structurally impossible objects. In addition, the results challenge the view that object decision and explicit recognition necessarily draw on separate memory systems,with only the former being supported by these descriptions of global object shape. It seems that recognition also can be supported by these descriptions, provided the original encoding conditions encourage their derivation. Hearing an object named at encoding appears to be just such a condition. These observations are discussed in relation to the effects of naming in other visual tasks, and to the role of visual attention in object identification

    Automatic Metro Map Layout Using Multicriteria Optimization

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    This paper describes an automatic mechanism for drawing metro maps. We apply multicriteria optimization to find effective placement of stations with a good line layout and to label the map unambiguously. A number of metrics are defined, which are used in a weighted sum to find a fitness value for a layout of the map. A hill climbing optimizer is used to reduce the fitness value, and find improved map layouts. To avoid local minima, we apply clustering techniques to the map the hill climber moves both stations and clusters when finding improved layouts. We show the method applied to a number of metro maps, and describe an empirical study that provides some quantitative evidence that automatically-drawn metro maps can help users to find routes more efficiently than either published maps or undistorted maps. Moreover, we found that, in these cases, study subjects indicate a preference for automatically-drawn maps over the alternatives

    The Effect of Maternal Tetanus Immunization on Children’s Schooling Attainment in Matlab, Bangladesh: Follow-up of a Randomized Trial

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    We investigate the effects of ante-natal maternal vaccination against tetanus on the schooling attained by children in Bangladesh. Maternal vaccination prevents the child from acquiring tetanus at birth through blood infection and substantially reduces infant mortality and may prevent impairment in children who would otherwise acquire tetanus but survive. We follow up on a 1974 randomized trial of maternal tetanus toxoid, looking at outcomes for children born in the period 1975-1979. We find significant schooling gains from maternal tetanus vaccination for children whose parents had no schooling, showing a large impact on a small number of children.Vaccination, tetanus, schooling, education, Bangladesh

    Lethal Parasites in Oysters from Coastal Georgia with Discussion of Disease and Management Implications

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    Extensive mortalities of oysters, Crassostrea virginica, occurred from 1985 through 1987 in coastal waters of Georgia. Fluid thioglycolate cultures of oysters collected from 16 of 17 locations revealed infections by the apicomplexan parasite Perkinsus marinus. An ascetosporan parasite, Haplosporidium nelsoni, was also observed in histopathological examination of oysters from 4 of the locations. While the range of H. nelsoni currently is recognized as the east coast of the United States from Maine to Florida, this is the first report of the parasite in Georgia waters. This paper documents the occurrence of these two lethal parasites in oysters from coastal waters of Georgia, along with potential disease and management implications. Results of an earlier independent and previously unpublished survey are also discussed which document the presence of P. marinus in Georgia as early as 1966

    Health and economic benefits of achieving hepatitis C virus elimination in Pakistan: A modelling study and economic analysis

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    Background: Modelling suggests that achieving the WHO incidence target for hepatitis C virus (HCV) elimination in Pakistan could cost US3.87billionover2018to2030.However,theeconomicbenefitsfromintegratingservicesorimprovingproductivitywerenotincluded.Methodsandfindings:WeadaptaHCVtransmissionmodelforPakistantoestimatetheimpact,costs,andcosteffectivenessofachievingHCVelimination(reducingannualHCVincidenceby803.87 billion over 2018 to 2030. However, the economic benefits from integrating services or improving productivity were not included.Methods and findings: We adapt a HCV transmission model for Pakistan to estimate the impact, costs, and cost-effectiveness of achieving HCV elimination (reducing annual HCV incidence by 80% by 2030) with stand-alone service delivery, or partially integrating one-third of initial HCV testing into existing healthcare services. We estimate the net economic benefits by comparing the required investment in screening, treatment, and healthcare management to the economic productivity gains from reduced HCV-attributable absenteeism, presenteeism, and premature deaths. We also calculate the incremental cost-effectiveness ratio (ICER) per disability-adjusted life year (DALY) averted for HCV elimination versus maintaining current levels of HCV treatment. This is compared to an opportunity cost-based willingness-to-pay threshold for Pakistan (US148 to US198/DALY).Comparedtoexistinglevelsoftreatment,scalingupscreeningandtreatmenttoachieveHCVeliminationinPakistanaverts5.57(95198/DALY). Compared to existing levels of treatment, scaling up screening and treatment to achieve HCV elimination in Pakistan averts 5.57 (95% uncertainty interval (UI) 3.80 to 8.22) million DALYs and 333,000 (219,000 to 509,000) HCV-related deaths over 2018 to 2030. If HCV testing is partially integrated, this scale-up requires an investment of US1.45 (1.32 to 1.60) billion but will result in US1.30(0.94to1.72)billioninimprovedeconomicproductivityover2018to2030.Thiseliminationstrategyishighlycosteffective(ICER=US1.30 (0.94 to 1.72) billion in improved economic productivity over 2018 to 2030. This elimination strategy is highly cost-effective (ICER = US29 per DALY averted) by 2030, with it becoming cost-saving by 2031 and having a net economic benefit of US$9.10 (95% UI 6.54 to 11.99) billion by 2050. Limitations include uncertainty around what level of integration is possible within existing primary healthcare services as well as a lack of Pakistan-specific data on disease-related healthcare management costs or productivity losses due to HCV.Conclusions: Investment in HCV elimination can bring about substantial societal health and economic benefits for Pakistan

    Interpretation of photocurrent transients at semiconductor electrodes:Effects of band-edge unpinning

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    The transient photocurrent response of semiconductor electrodes to chopped illumination often shows spikes and overshoots that are usually interpreted as evidence that surface recombination is occurring. In the case of the high intensities used for light-driven water splitting, the interpretation is less straightforward since the electron transfer reactions are so slow that the minority carrier concentration at or near the surface increases to high values that modify the potential drop across the Helmholtz layer in the electrolyte, leading to ‘band edge unpinning’. In addition, changes in chemical composition of the surface or local changes in pH may also alter the potential distribution across the semiconductor/electrolyte junction. A quantitative theory of band edge unpinning due to minority carrier build up is presented, and numerical calculations of transient photocurrent responses are compared with experimental examples for n-type Fe2O3 and p-type lithium-doped CuO electrodes. It is shown that the apparently high reaction orders (up to third order) with respect to hole concentration reported for hematite photoanodes can be explained as arising from an acceleration of hole transfer by the increased voltage drop across the Helmholtz layer associated with band edge unpinning. The limitations of the band edge unpinning model are discussed considering additional effects associated with modification of the potential distribution brought about by light-induced changes in surface composition, surface dipoles and surface ionic charge.</p

    Iron and sulfur in the pre-biologic ocean

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    Tentative geochemical cycles for the pre-biologic Earth are developed by comparing the relative fluxes of oxygen, dissolved iron, and sulfide to the atmosphere and ocean. The flux of iron is found to exceed both the oxygen and the sulfide fluxes. Because of the insolubility of iron oxides and sulfides the implication is that dissolved iron was fairly abundant and that oxygen and sulfide were rare in the atmosphere and ocean. Sulfate, produced by the oxidation of volcanogenic sulfur gases, was the most abundant sulfur species in the ocean, but its concentration was low by modern standards because of the absence of the river-borne flux of dissolved sulfate produced by oxidative weathering of the continents.These findings are consistent with the geologic record of the isotopic composition of sedimentary sulfates and sulfides. Except in restricted environments, the sulfur metabolism of the earliest organisms probably involved oxidized sulfur species not sulfide.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25676/1/0000229.pd
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