1,152 research outputs found
A Complex Stereochemical Relay Approach To The Antimalarial Alkaloid Ocimicide A1. Evidence For A Structural Revision
Ocimicide A1 (1) and the semisynthetic derivative ocimicide A2 (2) are highly potent antimalarial agents efficacious against chloroquine-sensitive and -resistant Plasmodium falciparum strains with IC50 values in the nanomolar and picomolar range, respectively. Members of this family have demonstrated radical cure in rhesus monkeys, without detectable toxicity, but their structureâfunction relationships and mechanism of action are unknown. Herein we describe a twelve-step synthesis of an advanced N-acylated pentacyclic precursor to the proposed structure of 1 (11% overall yield). Instability and poor P. falciparum growth inhibition of the corresponding free donorâacceptor cyclopropylamine, and large discrepancies between reported and both experimental and DFT-calculated 13C chemical shifts and coupling constants, suggest that substantial revision of the proposed structures may be necessary
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The Antarctic Flags project: a flagship outreach campaign for international cooperation
Antarctica does not have a flag. It is not a country, it has no indigenous population, and there is no government. Despite many countries laying claim to (often overlapping) parts of this frozen region, the continent was ultimately designated as a scientific preserve through the Antarctic Treaty. Military activity is explicitly banned by the Treaty, as are any activities that âshall constitute a basis for asserting, supporting or denying a claim to territorial sovereignty in Antarctica or create any rights of sovereignty in Antarcticaâ (Article IV, Clause 2). The resulting tenet of scientific cooperation and collaboration underpins all modern activity on the continent and, ultimately, embodies the ideals of Antarctica and notions of Antarcticness.
So why, every year, are hundreds of flags designed for Antarctica and sent to the continent from all over the world, if the continent is only to be used for peaceful activities?
Originally conceived by the Foundation for the Good Governance of International Spaces, or âOur Spacesâ,1 the Antarctic Flags project aims to connect schoolchildren to Antarctica through taking their flag designs to be flown on the frozen continent. The project was designed to be a school- level activity that could be carried out in celebration of Antarctica Day, which was established after the Antarctic Treaty Summit in 2009 to carry on the legacy of the Antarctic Treaty.2 The project, devised by Julie Hambrook Berkman, and expanded by the Association of Polar Early Career Scientists (APECS), the International Polar Foundation (IPF) and Polar Educators International (PEI), is now coordinated by early career scientists from the UK Polar Network (UKPN) and has involved participants from every non-Antarctic continent. Teachers are sent lesson suggestions, so that their students gain a true understanding of Antarcticaâs unique position among the Earthâs continents before they create their designs. Flags from each school are then sent on to those travelling to Antarctica for scientific purposes to display (Figures 11.1â11.3).
Here, we reflect on the impact of bringing Antarctica and Antarcticness into the classroom, discuss the evolution of the project with previous participants, and deliberate on perceptions of Antarctica, a continent which the majority of people will never visit, but still have a deep interest in
Land Allocation Effects of the Global Ethanol Surge: Predictions from the International FAPRI Model
We quantify the emergence of biofuel markets and its impact on U.S. and world agriculture for the coming decade using the multi-market multi-commodity international FAPRI model. The model incorporates the tradeoffs between biofuel, feed, and food production and consumption and international feedback effects of the emergence through world commodity prices and trade. We examine land allocation by type of crop, and pasture use for countries growing feedstock for ethanol (corn, sorghum, wheat, sugarcane, and other grains) and major crops competing with feedstock for land resources such as oilseeds. We shock the model with exogenous changes in ethanol demand, first in the United States, then in Brazil, China, EU, and India, and compute shock multipliers for land allocation decisions for crops and countries of interest. The multipliers show at the margin how sensitive land allocation is to the growing demand for ethanol. Land moves away from major crops and pasture competing for resources with feedstock crops. Because of the high U.S. tariff on ethanol, higher U.S. demand for ethanol translates into a U.S. ethanol production expansion. The latter has global effects on land allocation as higher coarse grains prices transmit worldwide. Changes in U.S. coarse grain prices also affect U.S. wheat and oilseeds prices, which are all transmitted to world markets. In contrast, expansion in Brazil ethanol use and production chiefly affects land used for sugarcane production in Brazil and to a lesser extent in other sugar-producing countries, but with small impact on other land uses in most countries. Keywords: Acreage, area, biofuel, corn, crops, ethanol, FAPRI model, feedstock, land, sugar, sugarcane. JEL Code: Q42 Q17 Q15ethanol; acreage; area; biofuel; corn; crops; FAPRI model; feedstock; land; sugar; sugarcane
The Global Bioenergy Expansion: How Large Are the FoodâËâFuel Trade-Offs?
We summarize a large set of recent simulations and policy analyses based on FAPRIâs world multimarket, partial-equilibrium models. We first quantify and project the emergence of biofuel markets in US and world agriculture for the coming decade. Then, we perturb the models with incremental shocks in US and world ethanol consumption in deviation from this projected emergence to assess their effects on world agricultural and food markets. Various food-biofuel trade-offs are quantified and examined. Increases in food prices are moderate for the US ethanol expansion and even smaller for the ethanol expansion outside the United States, which is based on sugarcane feedstock, which has little feedback on other markets. With the US expansion, the high protection in the US ethanol market limits potential adjustments in the world ethanol markets and increases the demand for feedstock within the United States. Changes in US grain and oilseed market prices propagate to world markets, as the United States is a large exporter in these markets. With changes in world prices, land allocation in the rest of the world responds to the new relative prices as in the United States but with smaller magnitudes because price transmission to local markets is less than full.ethanol; biofuel; land effects; food prices; trade-offs
Land Allocation Effects of the Global Ethanol Surge: Predictions from the International FAPRI Model
We quantify the emergence of biofuel markets and its impact on U.S. and world agriculture for the coming decade using the multi-market, multi-commodity international FAPRI (Food and Agricultural Policy Research Institute) model. The model incorporates the trade-offs between biofuel, feed, and food production and consumption and international feedback effects of the emergence through world commodity prices and trade. We examine land allocation by type of crop, and pasture use for countries growing feedstock for ethanol (corn, sorghum, wheat, sugarcane, and other grains) and major crops competing with feedstock for land resources such as oilseeds. We shock the model with exogenous changes in ethanol demand, first in the United States, then in Brazil, China, the European Union-25, and India, and compute shock multipliers for land allocation decisions for crops and countries of interest. The multipliers show at the margin how sensitive land allocation is to the growing demand for ethanol. Land moves away from major crops and pasture competing for resources with feedstock crops. Because of the high U.S. tariff on ethanol, higher U.S. demand for ethanol translates into a U.S. ethanol production expansion. The latter has global effects on land allocation as higher coarse grain prices transmit worldwide. Changes in U.S. coarse grain prices also affect U.S. wheat and oilseed prices, which are all transmitted to world markets. In contrast, expansion in Brazil ethanol use and production chiefly affects land used for sugarcane production in Brazil and to a lesser extent in other sugar-producing countries, but with small impacts on other land uses in most countries.acreage; area; biofuel; corn; crops; ethanol; FAPRI model; feedstock; land; sugar; sugarcane
Role of Gut Microbiota in Cardiovascular Disease that Links to Host Genotype and Diet
Cardiovascular diseases (CVDs) are major outcomes of metabolic impairments in humans, which result from several genetic and environmental factors. In recent years, a âmicrobiome hypothesisâ has been proposed as a result of several studies that have attempted to understand underlying mechanisms of CVDs. Similar to CVDs, both genetic and environmental factors, especially diets, have a major impact on shaping gut microbiota and their functions. In the past decade, strong evidence has emerged to confirm the role of gut microbiota in contributing to the onset of CVDs. However, a comprehensive understanding of interactions among diet, host genotype, gut microbiota and CVDs is still facing challenges due to the complicated nature of CVDs. In this chapter, we review the present state of our knowledge about the contributory role of gut microbiota in CVDs and discuss the knowledge gaps that warrant further investigations. Moreover, we review the potential intervention strategies that may target the microbiota-driven pathology in CVDs and discuss the strength and weakness of animal models in studying the roles of gut microbiota in CVDs
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