6,721 research outputs found

    Apollo experience report: Guidance and control systems; lunar module mission programer

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    A review of the concept, operational requirements, design, and development of the lunar module mission programer is presented, followed by a review of component and subsystem performance during design-feasibility, design-verification, and qualification tests performed in the laboratory. The system was further proved on the unmanned Apollo 5 mission. Several anomalies were detected, and satisfactory solutions were found. These problems are defined and examined, and the corrective action taken is discussed. Suggestions are given for procedural changes to be used if future guidance and control systems of this type are to be developed

    Exploring modality switching effects in negated sentences: further evidence for grounded representations

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    Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing ā€œnotā€). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation

    Race and Health Disparities Among Seniors in Urban Areas in Brazil

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    White seniors report better health than Black seniors in urban areas in Sao Paulo, Brazil. This is the case even after controlling for baseline health conditions and several demographic, socio-economic and family support characteristics. Furthermore, adjusted racial disparities in self-reported health are larger than the disparities found using alternative measures of functional health. Our empirical research in this paper suggests that the two most important factors driving racial disparities in health among seniors (in our sample) are historical differences in rural living conditions and current income. Present economic conditions are more relevant to racial disparities among poor seniors than among rich seniors. Moreover, racial differences in health not attributable to observable characteristics are more important when comparing individuals in the upper half of the income distribution.

    Urbanization in the developing world: too early or too slow?

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    We describe patterns of urbanization in the developing world and the extent to which they differ from the developed world. We consider the extent to which urbanization in the developing world can be explained by conventional models of spatial equilibrium. Despite their relative poverty, developing world cities are relatively highly productive, and often provide good access to safe water, improved sanitation, schooling and inoculations. In some parts of the world, they are home to a surprisingly small number of factory workers and a surprisingly large number of farmers. Developing world cities seem to do less well at protecting their residents from lifestyle diseases and crime, their female residents from domestic violence and their children from illness. In thinking about these facts, we note that one strand of the literature focused on structural transformation has suggested that urbanization in the developing is occurring `too earlyā€™, while another strand argues that urbanization is occurring `too slowā€™ to be consistent with conventional models of spatial equilibrium. Despite many differences between developing and developed world cities, our new results combined with those in the literature suggest that models of spatial equilibrium can be adapted to be a useful guide to understanding the process of urbanization in the developing world

    Screening for Parkinsonā€™s Disease with Response Time Barriers: A Pilot Study

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    Background: Although significant response time deficits (both reaction time and movement time) have been identified in numerous studies of patients with Parkinsonā€™s disease (PD), few attempts have been made to evaluate the use of these measures in screening for PD. Methods: Receiver operator characteristic curves were used to identify cutoff scores for a unitweighted composite of two choice response tasks in a sample of 40 patients and 40 healthy participants. These scores were then cross-validated in an independent sample of 20 patients and 20 healthy participants. Results: The unit-weighted movement time composite demonstrated high sensitivity (90%) and specificity (90%) in the identification of PD. Movement time was also significantly correlated (r = 0.59, p \u3c 0.025) with the motor score of the Unified Parkinsonā€™s Disease Rating Scale (UPDRS). Conclusions: Measures of chronometric speed, assessed without the use of biomechanically complex movements, have a potential role in screening for PD. Furthermore, the significant correlation between movement time and UPDRS motor score suggests that movement time may be useful in the quantification of PD severity

    A Description of the Shelf Edge Groundfish Habitat Along the Southeastern United States

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    The rocky outcrops at the shelf edge along the southeastern United States provide a diverse and complex series of subhabitats inhabited by groundfish of both commercial and recreational importance. Reef morphology ranged from rounded outcrops of relatively low relief (less than 0.5 m) to steep scarps with as much as 15m relief. Groundfish species composition and density of a community off Charleston, S. C. were determined by counts from underwater television. More precise quantitative estimates of subhabitat area, greater replicate abundance sampling within discrete subhabitats and the incorporation of information on groundfish behavioral response to environmental factors and sampling techniques are necessary prior to realistic estimates of regional habitat carrying capacity and/or estimating absolute groundfish abundance
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