Indiana University – Purdue University Fort Wayne
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The Distribution of Amur Honeysuckle and Box Turtle Habitat Use in an Urban Forest
No full textUrban forests face major challenges to their ecological integrity because they are often small in size, surrounded by harsh edge-habitat, and can be vulnerable to colonization by invasive species. Lonicera maackii (Amur Honeysuckle) is considered one of the most problematic invasive species in the eastern US. In this study, we examined the distribution patterns of Amur Honeysuckle in an urban forest in Louisville, KY, USA, and the correlation between Amur Honeysuckle density and habitat use of Terrapene carolina (Box Turtle). We found no significant correlation between the density of young (\u3c1 m tall) Amur Honeysuckle and distance to forest edge or hiking trails or density of mature (\u3e1 m tall) Amur Honeysuckle and distance to forest edge. However, mature Amur Honeysuckle density increased as the distance from hiking trails increased. We also found no correlation between the density of young Amur Honeysuckle and Box Turtle habitat use, but at the landscape level, the likelihood of finding Box Turtles in an area decreases as the density of mature Amur Honeysuckle increases. Box Turtles were also more likely to be found in the vicinity of hiking trails than randomly selected points. Our results suggest that there is a negative correlation between mature Amur Honeysuckle density and Box Turtle habitat use, and that high densities of mature Amur Honeysuckle reduce available Box Turtle habitat
An Empirical Exploration of Chinese Imports and the US Steel Industry
No full textThe paper identifies four key issues concerning the relationship between Chinese imports and the US steel industry: currency manipulation, state-owned enterprises, subsidisation, and environmental regulations. Given these issues, we run a regression to empirically explore the relationship between Chinese imports and US steel prices. We found that Chinese imports have two conflicting effects: one is to lower US steel prices while the other is to increase the prices via China\u27s increasing market share. The overall impact is that Chinese imports increase US steel prices, as the effect due to market share is larger than the demand effect. With these findings, we suggest that, of the four effects considered, Chinese subsidisation is the most crucial
U.S. Economic Growth: Rahn Curve and Components of Government Spending
No full textThe controversial Rahn Curve is the relation of government spending with economic growth. It is argued that government spending is inefficient and should therefore be negatively related or uncorrelated with the growth of Gross Domestic Product (GDP). Whether there is a Rahn Curve is an empirical question which has been examined with mixed results for the U.S. economy. There has been little effort to disaggregate federal expenditures to see if there are components which are highly correlated with economic growth. However, some components of government spending which are theoretically related to economic growth, e.g., social security, funding of research grants, infrastructure building, and education. On the other hand, other expenditures such as debt service, police protection, even military spending does much to aid GDP growth. This paper uses components of federal expenditures as the explanatory variable for GDP growth
Toward understanding spatial dependence on epidemic thresholds in networks
No full textSocial influence in online social networks bears resemblance to epidemic spread in networks and has been studied through epidemiological models. The epidemic threshold is a fundamental metric used to evaluate epidemic spread in networks. Previous work has shown that the epidemic threshold of a network is exactly the inverse of the largest eigenvalue of its adjacency matrix. In this work, however, we indicate that such a threshold ignores spatial dependence among nodes and hence underestimates the actual epidemic threshold. Focusing on regular graphs, we analytically derive a more accurate epidemic threshold based on spatial Markov dependence. Our model shows that the epidemic threshold indeed depends on the spatial correlation coefficient between neighboring nodes and decreases with the death rate. Through both analysis and simulations, we show that our proposed epidemic threshold incorporates a certain spatial dependence and thus achieves a greater accuracy in characterizing the actual epidemic threshold in regular graphs. Moreover, we extend our study to irregular graphs by conjecturing a new epidemic threshold and show that such a threshold performs significantly better than previous work
Considerations for Testing Spatial Cognition in Mice
No full textThe Barnes maze has traditionally been used to evaluate visuospatial performance in rats, although the use of genetically modified mice has recently increased. However, few studies have documented the species differences that may affect performance. Here, we report methodological considerations for testing mice on a Barnes maze
Coastal leatherback turtles reveal conservation hotspot
No full textPrevious studies have shown that the world\u27s largest reptile - the leatherback turtle Dermochelys coriacea - conducts flexible foraging migrations that can cover thousands of kilometres between nesting sites and distant foraging areas. The vast distances that may be travelled by migrating leatherback turtles have greatly complicated conservation efforts for this species worldwide. However, we demonstrate, using a combination of satellite telemetry and stable isotope analysis, that approximately half of the nesting leatherbacks from an important rookery in South Africa do not migrate to distant foraging areas, but rather, forage in the coastal waters of the nearby Mozambique Channel. Moreover, this coastal cohort appears to remain resident year-round in shallow waters (\u3c50 m depth) in a relatively fixed area. Stable isotope analyses further indicate that the Mozambique Channel also hosts large numbers of loggerhead turtles Caretta caretta. The rare presence of a resident coastal aggregation of leatherback turtles not only presents a unique opportunity for conservation, but alongside the presence of loggerhead turtles and other endangered marine megafauna in the Mozambique Channel, highlights the importance of this area as a marine biodiversity hotspot
Genome-wide association studies of autoimmune vitiligo identify 23 new risk loci and highlight key pathways and regulatory variants
No full textVitiligo is an autoimmune disease in which depigmented skin results from the destruction of melanocytes, with epidemiological association with other autoimmune diseases. In previous linkage and genome-wide association studies (GWAS1 and GWAS2), we identified 27 vitiligo susceptibility loci in patients of European ancestry. We carried out a third GWAS (GWAS3) in European-ancestry subjects, with augmented GWAS1 and GWAS2 controls, genome-wide imputation, and meta-analysis of all three GWAS, followed by an independent replication. The combined analyses, with 4,680 cases and 39,586 controls, identified 23 new significantly associated loci and 7 suggestive loci. Most encode immune and apoptotic regulators, with some also associated with other autoimmune diseases, as well as several melanocyte regulators. Bioinformatic analyses indicate a predominance of causal regulatory variation, some of which corresponds to expression quantitative trait loci (eQTLs) at these loci. Together, the identified genes provide a framework for the genetic architecture and pathobiology of vitiligo, highlight relationships with other autoimmune diseases and melanoma, and offer potential targets for treatment