Publications by authors named "Robert E Dewar"

4 Publications

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Expert evaluation of traffic signs: conventional vs. alternative designs.

Ergonomics 2019 Jun 19;62(6):734-747. Epub 2019 Apr 19.

j Data Graph, Research and Statistical Consulting , Holon , Israel.

Traffic sign comprehension is significantly affected by their compliance with ergonomics design principles. Despite the UN Convention, designs vary among countries. The goal of this study was to establish theoretical and methodological bases for evaluating the design of conventional and alternative signs. Thirty-one conventional signs and 1-3 alternatives for each conventional sign were evaluated for their compliance with three ergonomics guidelines for sign design: physical and conceptual compatibility, familiarity and standardisation. Twenty-seven human factors and ergonomics experts from 10 countries evaluated the signs relative to their compliance with the guidelines. Analysis of variance across alternatives revealed that for 19 of the 31 signs, an alternative design received a significantly higher rating in its ergonomics design than the conventional sign with the same meaning. We also found a very high correlation between the experts' ratings and comprehension from previous studies. In conclusion, many countries use signs for which better alternative designs exist, and therefore UN Convention signs should be re-examined, and ergonomics experts evaluation can serve as a good surrogate for road users' comprehension surveys. This study presents theoretical and methodological bases for evaluating the design of UN Conventional and alternative traffic signs. Human factors and ergonomics experts evaluated 31 conventional and 68 alternative road signs, based on ergonomics principles for sign design. Results indicated the need to re-examine poorly designed UN Convention signs.
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http://dx.doi.org/10.1080/00140139.2019.1567829DOI Listing
June 2019

Stone tools and foraging in northern Madagascar challenge Holocene extinction models.

Proc Natl Acad Sci U S A 2013 Jul 15;110(31):12583-8. Epub 2013 Jul 15.

Department of Anthropology, Yale University, New Haven, CT 06520-8277, USA.

Past research on Madagascar indicates that village communities were established about AD 500 by people of both Indonesian and East African heritage. Evidence of earlier visits is scattered and contentious. Recent archaeological excavations in northern Madagascar provide evidence of occupational sites with microlithic stone technologies related to foraging for forest and coastal resources. A forager occupation of one site dates to earlier than 2000 B.C., doubling the length of Madagascar's known occupational history, and thus the time during which people exploited Madagascar's environments. We detail stratigraphy, chronology, and artifacts from two rock shelters. Ambohiposa near Iharana (Vohémar) on the northeast coast, yielded a stratified assemblage with small flakes, microblades, and retouched crescentic and trapezoidal tools, probably projectile elements, made on cherts and obsidian, some brought more that 200 km. (14)C dates are contemporary with the earliest villages. No food remains are preserved. Lakaton'i Anja near Antsiranana in the north yielded several stratified assemblages. The latest assemblage is well dated to A.D. 1050-1350, by (14)C and optically stimulated luminescence dating and pottery imported from the Near East and China. Below is a series of stratified assemblages similar to Ambohiposa. (14)C and optically stimulated luminescence dates indicate occupation from at least 2000 B.C. Faunal remains indicate a foraging pattern. Our evidence shows that foragers with a microlithic technology were active in Madagascar long before the arrival of farmers and herders and before many Late Holocene faunal extinctions. The differing effects of historically distinct economies must be identified and understood to reconstruct Holocene histories of human environmental impact.
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http://dx.doi.org/10.1073/pnas.1306100110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732966PMC
July 2013

Demography of Verreaux's sifaka in a stochastic rainfall environment.

Oecologia 2009 Sep 16;161(3):491-504. Epub 2009 Jun 16.

Department of Anthropology, Boston University, Boston, MA 02215, USA.

In this study, we use deterministic and stochastic models to analyze the demography of Verreaux's sifaka (Propithecus verreauxi verreauxi) in a fluctuating rainfall environment. The model is based on 16 years of data from Beza Mahafaly Special Reserve, southwest Madagascar. The parameters in the stage-classified life cycle were estimated using mark-recapture methods. Statistical models were evaluated using information-theoretic techniques and multi-model inference. The highest ranking model is time-invariant, but the averaged model includes rainfall-dependence of survival and breeding. We used a time-series model of rainfall to construct a stochastic demographic model. The time-invariant model and the stochastic model give a population growth rate of about 0.98. Bootstrap confidence intervals on the growth rates, both deterministic and stochastic, include 1. Growth rates are most elastic to changes in adult survival. Many demographic statistics show a nonlinear response to annual rainfall but are depressed when annual rainfall is low, or the variance in annual rainfall is high. Perturbation analyses from both the time-invariant and stochastic models indicate that recruitment and survival of older females are key determinants of population growth rate.
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http://dx.doi.org/10.1007/s00442-009-1382-1DOI Listing
September 2009

Evolution in the hypervariable environment of Madagascar.

Proc Natl Acad Sci U S A 2007 Aug 13;104(34):13723-7. Epub 2007 Aug 13.

McDonald Institute of Archaeological Research, University of Cambridge, Downing Street, Cambridge CB2 3ER, England.

We show that the diverse ecoregions of Madagascar share one distinctive climatic feature: unpredictable intra- or interannual precipitation compared with other regions with comparable rainfall. Climatic unpredictability is associated with unpredictable patterns of fruiting and flowering. It is argued that these features have shaped the evolution of distinctive characteristics in the mammalian fauna of the island. Endemic Herpestidae and Tenrecidae and members of five endemic primate families differ from closely related species elsewhere, exhibiting extremes of "fastness" and "slowness" in their life histories. Climatic features may also account for the dearth of frugivorous birds and mammals in Madagascar, and for the evolutionary prevalence of species with large body mass.
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http://dx.doi.org/10.1073/pnas.0704346104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1947998PMC
August 2007
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