2,262 research outputs found

    Requirements for the conceptual design of advanced underground coal extraction systems

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    Conceptual design requirements are presented for underground coal mining systems having substantially improved performance in the areas of production cost and miner safety. Mandatory performance levels are also set for miner health, environmental impact, and coal recovery. In addition to mandatory design goals and constraints, a number of desirable system characteristics are identified which must be assessed in terms of their impact on production cost and their compatibility with other system elements. Although developed for the flat lying, moderately thick seams of Central Appalachia, these requirements are designed to be easily adaptable to other coals

    Forms of Rational Agency

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    A measure of good and bad is internal to something falling under it when that thing falls under the measure in virtue of what it is. The concept of an internal standard has broad application. Compare the external breed standards arbitrarily imposed at a dog show with the internal standards of health at work in the veterinarian's office. This paper is about practical standards, measures of acting well and badly, and so measures deployed in deliberation and choice. More specifically, it is about the attempt to explain the unconditional validity of certain norms (say, of justice and prudence) by showing them to be internal to our agency and the causality it involves. This is constitutivism. Its most prominent incarnations share a set of assumptions about the nature of agency and our knowledge of it: conceptualism, formalism and absolutism. This essay investigates the merits and viability of rejecting all of them while still seeking the ground of practical normativity in what we are, in our fundamental activity

    Motivating social distancing during the Covid-19 pandemic: An online experiment. ESRI Working Paper No. 658 April 2020

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    Social distancing during the COVID-19 pandemic will save lives. We tested communication strategies to promote social distancing via an online experiment (N = 500) commissioned by Ireland’s Department of Health. A control group saw a current informational poster. Two treatment groups saw similar posters with messages that highlighted: (i) the risk of transmission to identifiable persons vulnerable to COVID-19; (ii) the exponential nature of transmission. We then measured judgements of behaviours previously identified by focus groups as “marginal” (meaning that people were not sure whether they were advisable, such meeting others outdoors, or visiting parents). We recorded intention to undertake behaviours and stated acceptability of behaviours. Our hypotheses, that both treatments would increase participants’ caution about marginal behaviours, were preregistered (i.e. lodged with an international organisation for open science before data collection). Results confirmed the hypotheses. The findings suggest that the thought of infecting vulnerable people or large numbers of people can motivate social distancing. This has implications for communications strategies. The stud

    Resource targets for advanced underground coal extraction systems

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    Resource targets appropriate for federal sponsorship of research and development of advanced underground coal mining systems are identified. A comprehensive examination of conventional and unconventional coals with particular attention to exceptionally thin and thick seams, steeply dipping beds, and multiple seam geometry was made. The results indicate that the resource of primary importance is flat lying bituminous coal of moderate thickness, under moderate cover, and located within the lower 48 states. Resources of secondary importance are the flat lying multiple seams and thin seams (especially those in Appalachia). Steeply dipping coals, abandoned pillars, and exceptionally thick western coals may be important in some regions of subregions, but the limited tonnage available places them in a position of tertiary importance

    Comparison of grouper assemblages in northern areas of the wider Caribbean: A preliminary assessment

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    Groupers (Pisces: Serranidae) are important top-level predators in wider Caribbean, but have experienced significant exploitation, resulting in declines in abundance, size, spawning aggregations, and changes in species composition. Larger groupers are particularly vulnerable to intense fishing because of their longevity, slow growth, delayed reproduction, and aggregate spawning. Marine fishery reserves (MFR), areas permanently closed to consumptive use, offer a viable means to protect grouper resources. This study reports on fishery-independent surveys of groupers in four regions of the tropical western Atlantic during 1995 - 1997: Florida Keys, central Bahamas, southeastern Cuba, and Dominican Republic. The regions surveyed included two national parks and a national marine sanctuay, and were further categorized as: 1) intensively fished with little or no management for groupers (Cuba, Dominican Republic); 2) intensively fished with gear and effort limitations (Florida Keys); 3) lightly fished with some management (N. and S. Exuma Cays, Bahamas); and 4) a. MFR closed to fishing since 1986 (Exuma Cays Land and Sea Park, Bahamas). From 10 - 20 strip transects (20 m x 5 m) were surveyed in shallow-water (l-20 m depth) hard-bottom habitats for grouper species composition, density, and size distribution. Nine grouper species (6 Epinephelus spp., 3 Mycteroperca spp.) were documented among all regions. Areas in which groupers were partially or wholly protected from fishing had greater grouper diversity, density, and biomass, particularly for targeted species such as Nassau grouper (E. striatus). Classification of groupers by three size classes (small, intermediate, large) indicated a distinct gradient from areas with intense fishing to the MFR. In three of the regions affected by intense fishing, one of which has several grouper fishery regulations, grouper abundance and biomass were dominated by non-targeted species such as the graysby (E. cruentatus) and coney (E. fulvus). This second-order effect of fishing probably indicates competitive or predation. MFRs represent a viable means to protect grouper resources, alleviating the complications of enforcement and partially the need to gather fisheries dependent data. The ability of groupers to recover in certain regions may be deterred because of reduced larval recruitment from upstream, heavily fished sources

    Stillbirth risk across pregnancy by size for gestational age in Western Cape Province, South Africa: Application of the fetuses-at-risk approach using perinatal audit data

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    Background. There is little published work on the risk of stillbirth across pregnancy for small-for-gestational-age (SGA) and large-for-gestational (LGA) pregnancies in low-resource settings.Objectives. To compare stillbirth risk across pregnancy between SGA and appropriate-for-gestational-age (AGA) pregnancies in Western Cape Province, South Africa (SA).Methods. A retrospective audit of perinatal mortality data using data from the SA Perinatal Problem Identification Program was conducted. All audited stillbirths with information on size for gestational age (N=677) in the Western Cape between October 2013 and August 2015 were included in the study. The Western Cape has antenatal care (ANC) appointments at booking and at 20, 26, 32, 34, 36, 38 and 41 (if required) weeks’ gestation. A fetuses-at-risk approach was adopted to examine stillbirth risk (28 - 42 weeks’ gestation, ≄1 000 g) across gestation by size for gestational age (SGA <10th centile Theron growth curves, LGA >90th centile). Stillbirth risk was compared between SGA/LGA and AGA pregnancies.Results. SGA pregnancies were at an increased risk of stillbirth compared with AGA pregnancies between 30 and 40 weeks’ gestation, with the relative risk (RR) ranging from 3.5 (95% confidence interval (CI) 1.6 - 7.6) at 30 weeks’ gestation to 15.3 (95% CI 8.8 - 26.4) at 33 weeks’ gestation (p<0.001). The risk for LGA babies increased by at least 3.5-fold in the later stages of pregnancy (from 37 weeks) (p<0.001). At 38  weeks, the greatest increased risk was seen for LGA pregnancies (RR 6.6, 95% CI 3.1 - 14.2; p<0.001).Conclusions. There is an increased risk of stillbirth for SGA pregnancies, specifically between 33 and 40 weeks’ gestation, despite fortnightly ANC visits during this time. LGA pregnancies are at an increased risk of stillbirth after 37 weeks’ gestation. This high-risk period highlights potential issues with the detection of fetuses at risk of stillbirth even when ANC is frequent.
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