984 research outputs found
Hypoaspis muellerae Halliday 2005
No full textHypoaspis muellerae Halliday, 2005 (Figs 38–45) Hypoaspis muellerae Halliday, 2005: 32. Specimens examined. Five paratypes (ANIC 51-002833 – 51-002837) were examined by the first author from Australian National Insect Collection, Canberra (Australia), and each microslide containing one female labelled as: Hypoaspis muellerae Halliday, South Africa, Plettenberg Bay, 18 August 1994, Roadside picnic area, TK. Qin coll., Clover, cape weed, site 30–13. Halliday (2005) described Hypoaspis muellerae from Plettenberg Bay, South Africa. We have re-examined the paratypes of this species, and now take the opportunity to make some additions to the original description. In the description of this species (Halliday, 2005, Fig. 17) setae st4 are obviously present but that was an error, and in all the specimens we examined setae st4 were absent (Figs 39 & 41). The description did not mention the location of iv3, but they are located on the posterolateral angles of the sternal shield in all the specimens we examined (Fig. 41). This species shows some significant morphological character states typical of Laelaspisella: (1) dorsal shield hypertrichous and with at least 11–13 non-secretory slit-like lyrifissures (Figs 38 & 40); (2) metasternal setae st4 absent (Figs 39 & 41); (3) genitiventral shield large, broad and rounded posteriorly (Fig. 39); (4) iv3 located on posterolateral angles of sternal shield (Fig. 41); (5) internal malae densely fringed and with elongate threads (Fig. 42); (6) lateral margin of epistome smooth and anteriorly mucronated (Fig. 43); (7) palp tarsal claw with two tines (Fig. 44). However, it differs from the original concept of Laelaspisella as described by Marais & Loots (1969), because the dorsal cheliceral seta is present (Fig. 45).Published as part of Joharchi, Omid, Ramroodi, Sara & Halliday, Bruce, 2020, Review of the genus Pogonolaelaps Nemati & Gwiazdowicz (Acari: Laelapidae) with description of a new species from Iran, pp. 465-484 in Zootaxa 4820 (3) on pages 477-481, DOI: 10.11646/zootaxa.4820.3.3, http://zenodo.org/record/439805
Essays in Applied Microeconomics
No full textThis dissertation is composed of three chapters that apply econometric techniques to solve questions in the health and labor economics fields. The first chapter assesses the impact of obesity on labor market outcomes over economic downturns. Specifically, I measure labor market differentials between obese and healthy weight workers over business cycle fluctuations using two national surveys. I find that when unemployment increases, obese individuals experience larger declines in income relative to those who are not obese. These findings are robust to the inclusion of occupation fixed effects, suggesting the findings cannot be fully explained by obese workers selecting careers that tend to have greater sensitivity to business cycle fluctuations. The second chapter of this dissertation is joint work with Timothy Halliday, Lester Lusher, and Aureo de Paula. This study pairs variation stemming from volcanic eruptions with panel data on the census of Hawai`i public student test scores to estimate the impact of pollutants on student performance. We first precisely estimate a small drop in average test scores. Then, utilizing Hawai`i's rich diversity across schools in baseline exposure, we estimate sharp nonlinearities - effects for schools with PM 2.5 levels above 9 units are nearly five times the magnitude as for schools below. Lastly, we find that the drop in test scores for economically disadvantaged students is nearly four times the magnitude of their advantaged counterparts. This performance gap across student type arises from within school variation, suggesting the gap cannot be explained by differences in school resources. The final chapter of this dissertation is in collaboration with Maya Ward. In this study, we use the 1997 cohort of the National Longitudinal Survey of Youth (NLSY) to analyze the effect of economic downturns on labor market outcomes differentially across the Big Five personality traits. There is still a large amount of unexplained variation in various labor market outcomes after accounting for observable characteristics (age, gender, education, etc) indicating that unobservable characteristics (personality, work ethic, etc) may also play an important role. While the psychology literature has investigated the relationship between personality and labor market outcomes, there are far fewer studies that incorporate personality traits in the economics literature. Furthermore, findings that assess the impacts of the Big Five on economic outcomes are mixed due to differences in the data used. We find that those who report higher levels of emotional instability tend to see larger unemployment insurance take up and fewer weeks of employment during economic downturns relative to those who are more emotionally stable. Additionally, the effects do not seem to be driven by employer discrimination, as it may be that higher levels of emotional instability cause workers to be less productive during recessions.Ph.D
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Trials of Timothy John Evans and John Reginald Halliday Christie. /
No full textWeight Gain in Adolescents and Their Peers
No full textDespite the urgent public health implications, relatively little is yet known about the effect of peers on adolescent weight gain. We describe trends and features of adolescent BMI in a nationally representative dataset and document correlations in weight gain among peers. We find strong correlations between own body mass index (BMI) and peers’ BMI’s. Though the correlations are especially strong in the upper ends of the BMI distribution, the relationship is smooth and holds over almost the entire range of adolescent BMI. Furthermore, the results are robust to the inclusion of school fixed effects and basic controls for other confounding factors such as race, sex, and age. Some recent research in this area asks whether or not adolescent weight gain is caused by peers. We discuss the econometric difficulties in plausibly estimating such effects. Our results do not rule out the existence of these types of social network effects.obesity, peer effects, adolescent health
Book review: travelling westwards with closed minds
No full textFred Halliday reviews an historical study of Muslim approached to Europe and questions some of its conclusions [author reviews: Bernard Lewis, "The Muslim discovery of Europe"]
Income Volatility and Health
No full textWe investigate the impact of exogenous income fluctuations on health using twenty years of data from the Panel Study of Income Dynamics. To unravel the impact of income on health from unobserved heterogeneity and reverse causality, we employ techniques from the literature on the estimation of dynamic panel data models. Contrary to much of the previous literature on health and socio-economic status, we find that, on average, adverse income shocks lead to a deterioration of health. These effects are most pronounced for working-aged men and are dominated by transitions into the very bottom of the earnings distribution. We also provide suggestive evidence of an association between negative income shocks and higher mortality for working-aged men.Gradient, Health, Dynamic Panel Data Models, Recessions
Income Risk and Health
No full textWe investigate the impact of exogenous income shocks on health using twenty years of data from the Panel Study of Income Dynamic. To unravel the impact of income on health from unobserved heterogeneity and reverse causality, we employ techniques from the literature on the estimation of dynamic panel data models. Contrary to much of the previous literature on the gradient, we find that, on average, adverse income shocks lead to a deterioration of health. These effects are most pronounced for working-aged men and are dominated by transitions into the very bottom of the earnings distribution. We also provide suggestive evidence of an association between negative income shocks and higher mortality for working-aged men.Gradient, Recessions, Health, Dynamic Panel Data Models
EDWARD ALLEN. Modernist Invention: Media Technology and American Poetry Edward Allen. Modernist Invention: Media Technology and American Poetry. Pp. xii + 282. Cambridge, Cambridge University Press, 2020. Hardback, £75.
No full textThis is a pre-copyedited, author-produced version of an article accepted for publication in The Review of English Studies, following peer review. The version of record: Sam Halliday, EDWARD ALLEN. Modernist Invention: Media Technology and American Poetry, The Review of English Studies, hgaa100, https://doi.org/10.1093/res/hgaa100 is available online at: https://doi.org/10.1093/res/hgaa10
Health Inequality over the Life-Cycle
No full textWe investigate the evolution of health inequality over the life-course. Health is modeled as a latent variable that is determined by three factors: endowments, and permanent and transitory shocks. We employ Simulated Minimum Distance and the Panel Study of Income Dynamics to estimate the model. We estimate that permanent shocks account for under 10% of the total variation in health for the college educated, but between 35% and 70% of total health variability for people without college degrees. Consistent with this, we find that health inequality moves substantially more slowly over the life-course for the college educated.health, dynamic panel data models, variance decomposition
Business Cycles, Migration and Health
No full textThis paper uses data from the PSID to investigate how selective migration affects the relationship between business cycles and health. We show that, among the healthy, migration is used to insure against macroeconomic fluctuations. However, among the unhealthy, there is no relationship between migration and business cycles. In other words, illness erases a person’s ability to use migration to hedge against business cycle fluctuations. This suggests that recessions should induce an out-migration of disproportionately healthy people from economically depressed areas. This implies that - ceterus paribus - mortality and morbidity rates should be counter-cyclical.
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