225 research outputs found

    Advancing the determinants of risky decision behaviour using conjoint and multi-level moderated mediation analysis

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    Investment decision-making is an everyday activity within society. When these decisions involve innovation and require a willingness to innovate, additional complexities arise concerning uncertainty and decision irreversibility. This thesis investigates to what extent predictions of investment decision-making behaviour may be made based upon how varying levels of uncertainty and irreversibility affect perceptions of risk, how this may affect decision behaviour and how the strength of this effect may vary depending upon decision-maker risk propensity. In doing so, this thesis addresses important gaps found to exist at an intersection of the theory of innovation diffusion, the basic theory of irreversible investment under uncertainty and prospect theory. The research methodology employed for this purpose comprises full-profile conjoint value analysis and multi-level moderated mediation analysis. An online survey comprising ten conjoint tasks enables the conjoint analysis and provides the means to measure both perceptions of risk and risk propensity. The online survey itself relies upon an established case study titled ‘Carter Racing’. The results of this research find that a comprehensive set of relationships exist among the variables in question, from which valid and useful predictions may be made. Where a risk-averse relationship is shown to exist between decision-making behaviour and measures of uncertainty and irreversibility, it can also be shown that these relationships are exerted through and explained by perceptions of risk, with decision-maker risk propensity serving to influence the strength of the effects. In these cases, a significant positive correlation is observed between perceptions of risk and both uncertainty and irreversibility. A significant negative correlation is also observed between perceptions of risk and a willingness to innovate, this being the means through which innovativeness is measured. However, where a risk-seeking relationship is shown to exist, no significant correlations or effects are observed. These findings have important implications for theory and practice

    Ergodicity of the adic transformation on the Euler graph

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    The Euler graph has vertices labelled (n, k) for n = 0, 1, 2, ... and k = 0, 1, ..., n, with k + 1 edges from (n, k) to (n + 1, k) and n − k + 1 edges from (n, k) to (n + 1, k + 1). The number of paths from (0,0) to (n, k) is the Eulerian number A(n, k), the number of permutations of 1,2,...,n + 1 with exactly n − k falls and k rises. We prove that the adic (Bratteli-Vershik) transformation on the space of infinite paths in this graph is ergodic with respect to the symmetric measure

    Dietary iron intakes based on food composition data may underestimate the contribution of potentially exchangeable contaminant iron from soil

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    Iron intakes calculated from one-day weighed records were compared with those from same day analyzed duplicate diet composites collected from 120 Malawian women living in two rural districts with contrasting soil mineralogy and where threshing may contaminate cereals with soil iron. Soils and diet composites from the two districts were then subjected to a simulated gastrointestinal digestion and iron availability in the digests measured using a Caco-2 cell model. Median analyzed iron intakes (mg/d) were higher (p < 0.001) than calculated intakes in both Zombwe (16.6 vs. 10.1 mg/d) and Mikalango (29.6 vs. 19.1 mg/d), attributed to some soil contaminant iron based on high Al and Ti concentrations in diet composites. A small portion of iron in acidic soil from Zombwe, but not Mikalango calcareous soil, was bioavailable, as it induced ferritin expression in the cells, and may have contributed to higher plasma ferritin and total body iron for the Zombwe women reported earlier, despite lower iron intakes. In conclusion, iron intakes calculated from food composition data were underestimated, highlighting the importance of analyzing duplicate diet composites where extraneous contaminant iron from soil is likely. Acidic contaminant soil may make a small but useful contribution to iron nutrition

    Orion Capsule Handling Qualities for Atmospheric Entry

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    Two piloted simulations were conducted at NASA's Johnson Space Center using the Cooper-Harper scale to study the handling qualities of the Orion Command Module capsule during atmospheric entry flight. The simulations were conducted using high fidelity 6-DOF simulators for Lunar Return Skip Entry and International Space Station Return Direct Entry flight using bank angle steering commands generated by either the Primary (PredGuid) or Backup (PLM) guidance algorithms. For both evaluations, manual control of bank angle began after descending through Entry Interface into the atmosphere until drogue chutes deployment. Pilots were able to use defined bank management and reversal criteria to accurately track the bank angle commands, and stay within flight performance metrics of landing accuracy, g-loads, and propellant consumption, suggesting that the pilotability of Orion under manual control is both achievable and provides adequate trajectory performance with acceptable levels of pilot effort. Another significant result of these analyses is the applicability of flying a complex entry task under high speed entry flight conditions relevant to the next generation Multi Purpose Crew Vehicle return from Mars and Near Earth Objects

    Imaging Cool Giant Planets in Reflected Light: Science Investigations and Synergy with Habitable Planets

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    Planned astronomical observatories of the 2020s will be capable of obtaining reflected light photometry and spectroscopy of cool extrasolar giant planets. Here we explain that such data are valuable both for understanding the origin and evolution of giant planets as a whole and for preparing for the interpretation of similar datasets from potentially habitable extrasolar terrestrial planets in the decades to follow.Comment: Science white paper submitted to the Astro 2020 Decadal Survey on Astronomy and Astrophysics. Replace version to fix typo in co-signer name and add figure credit

    High contrast imaging at the LBT: the LEECH exoplanet imaging survey

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    In Spring 2013, the LEECH (LBTI Exozodi Exoplanet Common Hunt) survey began its ∼\sim130-night campaign from the Large Binocular Telescope (LBT) atop Mt Graham, Arizona. This survey benefits from the many technological achievements of the LBT, including two 8.4-meter mirrors on a single fixed mount, dual adaptive secondary mirrors for high Strehl performance, and a cold beam combiner to dramatically reduce the telescope's overall background emissivity. LEECH neatly complements other high-contrast planet imaging efforts by observing stars at L' (3.8 μ\mum), as opposed to the shorter wavelength near-infrared bands (1-2.4 μ\mum) of other surveys. This portion of the spectrum offers deep mass sensitivity, especially around nearby adolescent (∼\sim0.1-1 Gyr) stars. LEECH's contrast is competitive with other extreme adaptive optics systems, while providing an alternative survey strategy. Additionally, LEECH is characterizing known exoplanetary systems with observations from 3-5μ\mum in preparation for JWST.Comment: 12 pages, 5 figures. Proceedings of the SPIE, 9148-2

    The LEECH Exoplanet Imaging Survey: Limits on Planet Occurrence Rates Under Conservative Assumptions

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    We present the results of the largest L′L^{\prime} (3.8 μ3.8~\mum) direct imaging survey for exoplanets to date, the Large Binocular Telescope Interferometer (LBTI) Exozodi Exoplanet Common Hunt (LEECH). We observed 98 stars with spectral types from B to M. Cool planets emit a larger share of their flux in L′L^{\prime} compared to shorter wavelengths, affording LEECH an advantage in detecting low-mass, old, and cold-start giant planets. We emphasize proximity over youth in our target selection, probing physical separations smaller than other direct imaging surveys. For FGK stars, LEECH outperforms many previous studies, placing tighter constraints on the hot-start planet occurrence frequency interior to ∼20\sim20 au. For less luminous, cold-start planets, LEECH provides the best constraints on giant-planet frequency interior to ∼20\sim20 au around FGK stars. Direct imaging survey results depend sensitively on both the choice of evolutionary model (e.g., hot- or cold-start) and assumptions (explicit or implicit) about the shape of the underlying planet distribution, in particular its radial extent. Artificially low limits on the planet occurrence frequency can be derived when the shape of the planet distribution is assumed to extend to very large separations, well beyond typical protoplanetary dust-disk radii (≲50\lesssim50 au), and when hot-start models are used exclusively. We place a conservative upper limit on the planet occurrence frequency using cold-start models and planetary population distributions that do not extend beyond typical protoplanetary dust-disk radii. We find that ≲90%\lesssim90\% of FGK systems can host a 7 to 10 MJupM_{\mathrm{Jup}} planet from 5 to 50 au. This limit leaves open the possibility that planets in this range are common.Comment: 31 pages, 13 figures, accepted to A

    Felony Murder and Capital Punishment: an Examination of the Deterrence Question

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    A proper test of the deterrent effect of the death penalty must consider capital homicides. However, the criterion variable in most investigations has been total homicides—most of which bear no legal or theoretical relationship to capital punishment. To address this fundamental data problem, this investigation used Federal Bureau of Investigation data for 1976–1987 to examine the relationship between capital punishment and felony murder, the most common type of capital homicide. We conducted time series analyses of monthly felony murder rates, the frequency of executions, and the amount and type of television coverage of executions over the period. The analyses revealed occasional departures (for vehicle theft and narcotics killings) from the null hypotheses. However, on balance, and in line with the vast majority of capital punishment studies, this investigation found no consistent evidence that executions and the television coverage they receive are associated significantly with rates for total, index, or different types of felony murder

    Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

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    Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts
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