85 research outputs found

    What Does Human Capital Do? A Review of Goldin and Katz's The Race between Education and Technology

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    This revision: February 2, 2012. Original submission: January 11, 2012.Goldin and Katz’s The Race between Education and Technology is a monumental achievement that supplies a unified framework for interpreting how the demand and supply of human capital have shaped the distribution of earnings in the U.S. labor market over the 20th century. This essay reviews the theoretical and conceptual underpinnings of this work and documents the success of Goldin and Katz’s framework in accounting for numerous broad labor market trends. The essay also considers areas where the framework falls short in explaining several key labor market puzzles of recent decades and argues that these shortcomings can potentially be overcome by relaxing the implicit equivalence drawn between workers’ skills and their job tasks in the conceptual framework on which Goldin and Katz build. The essay argues that allowing for a richer set of interactions between skills and technologies in accomplishing job tasks both augments and refines the predictions of Goldin and Katz’s approach and suggests an even more important role for human capital in economic growth than indicated by their analysis

    SP701-A-Growing and Harvesting Switchgrass for Ethanol Production in Tennessee

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    Switchgrass is a warm-season perennial grass native to North America. The plant can reach heights up to 10 feet with an extensive root system. Once established, switchgrass well-managed for biomass should have a productive life of 10-20 years. Within the stand, switchgrass is an extremely strong competitor. However, it is not considered an invasive plant. Switchgrass adapts well to a variety of soil and climatic conditions. It is most productive on moderately well to well-drained soils of medium fertility and a soil pH at 5.0 or above. The high cellulosic content of switchgrass makes it a favorable feedstock for ethanol production. It is anticipated that switchgrass can yield sufficient biomass to produce approximately 500 gallons of ethanol per acre. While the Tennessee Biofuels Initiative includes a demonstration plant to make ethanol from switchgrass, the market for switchgrass as an energy crop remains limited. Producers will likely need to be located within 30 to 50 miles of a cellulosic ethanol plant. Producing switchgrass for energy generally occurs under some form of contractual arrangement with the end-user. To reap potential benefits from using switchgrass for cellulosic ethanol production, the system of production must be profitable for farmers and energy producers, as well as cost effective for consumers

    Patterns of Retinal Damage Facilitate Differential Diagnosis between Susac Syndrome and MS

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    Susac syndrome, a rare but probably underdiagnosed combination of encephalopathy, hearing loss, and visual deficits due to branch retinal artery occlusion of unknown aetiology has to be considered as differential diagnosis in various conditions. Particularly, differentiation from multiple sclerosis is often challenging since both clinical presentation and diagnostic findings may overlap. Optical coherence tomography is a powerful and easy to perform diagnostic tool to analyse the morphological integrity of retinal structures and is increasingly established to depict characteristic patterns of retinal pathology in multiple sclerosis. Against this background we hypothesised that differential patterns of retinal pathology facilitate a reliable differentiation between Susac syndrome and multiple sclerosis. In this multicenter cross-sectional observational study optical coherence tomography was performed in nine patients with a definite diagnosis of Susac syndrome. Data were compared with age-, sex-, and disease duration-matched relapsing remitting multiple sclerosis patients with and without a history of optic neuritis, and with healthy controls. Using generalised estimating equation models, Susac patients showed a significant reduction in either or both retinal nerve fibre layer thickness and total macular volume in comparison to both healthy controls and relapsing remitting multiple sclerosis patients. However, in contrast to the multiple sclerosis patients this reduction was not distributed over the entire scanning area but showed a distinct sectorial loss especially in the macular measurements. We therefore conclude that patients with Susac syndrome show distinct abnormalities in optical coherence tomography in comparison to multiple sclerosis patients. These findings recommend optical coherence tomography as a promising tool for differentiating Susac syndrome from MS
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