Foundations of Gulf of Mexico and Caribbean evolution : eight controversies resolved

Eight points of recurring controversy regarding the primary foundations of models of Gulf of Mexico and Caribbean tectonic evolution are identified and examined. The eight points are controversial mainly because of the disconnect between different scales of thinking by different workers, a common but unfortunate problem in the geological profession. Large-scale thinkers often are unaware of local geological detail, and local-scale workers fail to appreciate the level of evolutionary precision and constraint provided by regional tectonics and plate kinematics. The eight controversies are: (1) the degree of freedom in the Gulf-Caribbean kinematic framework that is allowed by Atlantic opening parameters; (2) the existence of a South Bahamas-Guyana Transform, and the role of this structure in Cuban, Bahamian, Trinidadian, and Guyanese evolution; (3) the anticlockwise rotation of the Yucatán Block during the opening of the Gulf of Mexico; (4) the Pacific origin of the Caribbean oceanic crust; (5) the Aptian age and plate boundary geometry of the onset of west-dipping subduction of Proto-Caribbean beneath Caribbean lithospheres; (6) the origin and causal mechanism of the Caribbean Large Igneous Province…not Galapagos!; (7) the number and origin of magmatic arcs in the northern Caribbean; and (8) the origin of Paleogene "flysch" deposits along northern South America: the Proto-Caribbean subduction zone. Here we show that there are viable marriages between the larger and finer scale data sets that define working and testable elements of the region's evolution. In our opinion, these marriages are geologically accurate and suggest that they should form discrete elements that can and be integrated into regional models of Gulf and Caribbean evolution. We also call upon different facets of the geological community to collaborate and integrate diverse data sets more openly, in the hopes of improving general understanding and limiting the publication of unnecessary papers which only serve to spread geological uncertainty

Environmental Tobacco Smoke Avoidance Among Pregnant African-American Nonsmokers

Background—Environmental tobacco smoke (ETS) exposure during pregnancy contributes to adverse infant health outcomes. Limited previous research has focused on identifying correlates of ETS avoidance. This study sought to identify proximal and more distal correlates of ETS avoidance early in pregnancy among African-American women. Methods—From a sample of low-income, black women (n=1044) recruited in six urban, prenatal care clinics (July 2001–October 2003), cotinine-confirmed nonsmokers with partners, household/ family members, or friends who smoked (n=450) were identified and divided into two groups: any past-7-day ETS exposure and cotinine-confirmed ETS avoidance. Bivariate and multivariate logistic regression analyses identified factors associated with ETS avoidance. Data were initially analyzed in 2004. Final models were reviewed and revised in 2007 and 2008. Results—Twenty-seven percent of pregnant nonsmokers were confirmed as ETS avoiders. In multivariate logistic regression analysis, the odds of ETS avoidance were increased among women who reported household smoking bans (OR=2.96; 95% CI=1.83, 4.77; p Conclusions—Social contextual factors were the strongest determinants of ETS avoidance during pregnancy. Results highlight the importance of prenatal screening to identify pregnant nonsmokers at risk, encouraging household smoking bans, gaining support from significant others, and fully understanding the interpersonal context of a woman’s pregnancy before providing behavioral counseling and advice to prevent ETS exposure

Trade regimes and GATT: resource-intensive vs. knowledge intensive growth

Trading blocks can help or hinder the liberalization of world trade. A determining factor is whether trade within the block is organized around traditional comparative advantages, or around economies of scale. Regional free trade agreements such as NAFTA can be a substitutes for global free trade when they are based on traditional comparative advantages; then each regional market develops market power and incentives to impose tariffs on the rest of the word. Alternatively, regional trade agreements can be complementary to global free trade. This occurs when the blocks are organized around the exploitation of economies of scale and based on knowledge-intensive sectors. I establish that external economies of scale produce incentives for expanded trade; they can defeat the standard argument for "optimal tariffs" and mitigate another negative feature of trading blocks: their tendency to divert trade from efficient to inefficient sources. The emergence of regional blocks organized around economies of scale can therefore lead to increasingly open international markets. I discuss policy implications for the EU and for free trade in the Americas

Development of a petrographic classification of fly-ash components from coal combustion and co-combustion. (An ICCP Classification System, Fly-Ash Working Group – Commission III.)

A new system for the microscopic classification of fly-ash components has been developed by the Fly-Ash Working Group, Commission III of the ICCP and is presented herein. The studied fly-ashes were obtained from the combustion of single coals of varied rank, coal blends, and coals blended with other fuels (biomass, petroleum coke), in different operating conditions and by means of different technologies. Microscopic images of the fly-ash samples were used to test the optical criteria proposed for classifying the fly-ash components. The classification system developed is based on a small number of microscopic criteria, subdivided into six independent levels or categories, three of which are directed at whole particle identification on the basis of nature, origin and type of fly-ash particle, while the other three levels are directed at the smaller section identification on the basis of character, structure and optical texture of unburned carbons. To classify the inorganic components of the fly-ash, the criterion proposed is composition in terms of metallic/non-metallic character. To establish the classification criteria the petrographers involved in the work performed three successive round robins. Evaluation of the results by using firstly descriptive statistics and then the criteria and parameters employed by the ICCP in their accreditation programs indicated that the classification of the fly-ash components was accurate and that there was only a minor bias. The main conclusion of this study was that the proposed criteria are valuable for identifying, and classifying fly-ash components and for describing the optical properties of fly-ash particles