9,648 research outputs found
Study to determine dielectric properties of sandstone, shale, coal, and slate
Triplicate dielectric constant and loss tangent measurements on samples of sandstone, shale, coal, and slate were performed. Each of the three necessary configurations of the coal material was sampled to obtain measurements, with each sample machined parallel to the coal layering orientation. The coal samples were machined perpendicular to the coal layering and measured. They were conditioned at 100% humidity and at room temperature and remeasured; then conditioned in an elevated environment, and remeasured for dielectric properties. The coal data appear to remain relatively constant over the microwave frequency region. At the Ghz frequencies, the relative dielectric constant of coal is slightly higher for the E-field parallel to the layers than for the perpendicular case
Evolution of size-dependent flowering in Onopordum illyricum: A quantitative assessment of the role of stochastic selection pressures
We explore the evolution of delayed, size-dependent reproduction in the monocarpic perennial Onopordum illyricum, using a range of mathematical models, parameterized with long-term field data. Analysis of the long-term data indicated that mortality, flowering, and growth were age and size dependent. Using mixed models, we estimated the variance about each of these relationships and also individual-specific effects. For the held populations, recruitment was the main density-dependent process, although there were weak effects of local density on growth and mortality Using parameterized growth models, which assume plants grow along a deterministic trajectory, we predict plants should flower at sizes approximately 50% smaller than observed in the field. We then develop a simple criterion, termed the "1-yr look-ahead criterion," based on equating seed production now with that of next year, allowing for mortality and growth, to determine at what size a plant should flower. This model allows the incorporation of variance about the growth function and individual-specific effects. The model predicts flowering at sizes approximately double that observed, indicating that variance about the growth curve selects for larger sizes at flowering. The 1-yr look-ahead approach is approximate because it ignores growth opportunities more than 1 yr ahead. To assess the accuracy of this approach, we develop a more complicated dynamic state variable model. Both models give similar results indicating the utility of the 1-yr look-ahead criterion. To allow for temporal variation in the model parameters, we used an individual-based model with a generic algorithm. This gave very accurate prediction of the observed flowering strategies. Sensitivity analysis of the model suggested that temporal variation in the parameters of the growth equation made waiting to flower more risky, so selected for smaller sizes at flowering. The models clearly indicate the need to incorporate stochastic variation in life-history analyses
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Geographies of Production I: Relationality revisited and the ‘practice shift’ in economic geography
This report considers recent developments and ongoing debates around relational economic geography, and a growing body work that has focused on economic practices as a means to better understand production processes and economic development. In particular it examines the critical reaction to relational thinking within the sub-discipline, and the nature of the debate about the degree to which relational work is - and needs to be - regarded as distinct from more traditional approaches to economic geography. It then considers how relational economic geography has become inflected towards an epistemological and methodological focus on practice. It argues that this engagement with economic practices provides the basis to respond to some of the limitations identified with earlier work, and opens up fruitful new potential for theorizing the nature of agency in the space economy
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Introduction: Urban revolutions in the age of global urbanism
This special issue, papers presented at an Urban Studies Foundation-funded conference in Jakarta (March 2011), examines the current ‘urban century’ in terms of three revolutions. Revolutions from above index the logics and norms of mainstream global urbanism, particularly the form they have taken as policymakers work with municipal officials worldwide to organise urban development around neoliberal norms. Revolutions from below refer to the multifaceted contestations of global urbanism that take place in and around cities, ranging from urban street demonstrations and occupations (such as those riveting the world in early 2011 when these papers were written) to the quotidian actions of those pursuing politics and livelihoods that subvert the norms of mainstream global urbanism. It also highlights conceptual revolutions, referencing the ongoing challenge of reconceptualising urban theory from the South – not simply as a hemispheric location or geopolitical category but an epistemological stance, staged from many different locations but always fraught with the differentials of power and the weight of historical geographies. Drawing on the insights of scholars writing from, and not just about, such locations, a further iteration in this ‘southern’ turn of urban theorising is proposed. This spatio-temporal conjunctural approach emphasises how the specificity of cities – their existence as entities that are at once singular and universal – emerges from spatio-temporal dynamics, connectivities and horizontal and vertical relations. Practically, such scholarship entails taking the field seriously through collaborative work that is multi-sited, engages people along the spectrum of academics and activists, and is presented before and scrutinised by multiple publics
A Survey for Satellites of Venus
We present a systematic survey for satellites of Venus using the
Baade-Magellan 6.5 meter telescope and IMACS wide-field CCD imager at Las
Campanas observatory in Chile. In the outer portions of the Hill sphere the
search was sensitive to a limiting red magnitude of about 20.4, which
corresponds to satellites with radii of a few hundred meters when assuming an
albedo of 0.1. In the very inner portions of the Hill sphere scattered light
from Venus limited the detection to satellites of about a kilometer or larger.
Although several main belt asteroids were found, no satellites (moons) of Venus
were detected.Comment: Published in July 2009 (Sheppard, S. and Trujillo, C. 2009, Icarus,
202, 12-16.
Manufacturing processes for fabricating graphite/PMR 15 polyimide structural elements
Investigations were conducted to obtain commercially available graphite/PMR-15 polyimide prepreg, develop an autoclave manufacturing process, and demonstrate the process by manufacturing structural elements. Controls were established on polymer, prepreg, composite fabrication, and quality assurance, Successful material quality control and processes were demonstrated by fabricating major structural elements including flat laminates, hat sections, I beam sections, honeycomb sandwich structures, and molded graphite reinforced fittings. Successful fabrication of structural elements and simulated section of the space shuttle aft body flap shows that the graphite/PMR-15 polyimide system and the developed processes are ready for further evaluation in flight test hardware
Twilight of the International Consensus: How Multinationals Squandered Their Tax Privileges
In September 2013, Exxon Mobil Corp. announced it would recognize gay marriage for its employees. This was front-page news, right up there with a New Jersey Supreme Court judge telling the state it had to do the same. Why? Because Exxon is a politically conservative oil company that makes most of its political donations to Republicans? No, because Exxon is such a huge non-state actor that anything it does is tantamount to a government action.
In The Power Elite, C. Wright Mills cogently explained how giant multinational corporations had escaped the writ of national governments. Exxon is one of the world’s ten largest multinational corporate groups measured by market value. At the time of this writing, nine companies on that list were American, along with around half of the fifty. Some of the world’s largest companies pay very little tax anywhere in the world. But to their home governments, they are often national champions.
Some other countries’ multinationals are unfairly skipping-out on their corporate tax obligations to Organization for Economic Cooperation and Development (OECD) member and observer countries. That was the genesis of the OECD Base Erosion and Profit Shifting project (BEPS), which has produced an action plan designed to repair and preserve the fragile international consensus in the short run, but may end up upsetting it in the long run. In the long run, the international consensus is dead, and everyone knows it; but BEPS has to be tried and allowed to fail first.
This Essay addresses issues with taxing multinationals and how they abuse their tax privileges. Further, this Essay discusses how BEPS must run its course and how a new international consensus is necessary to combat the shortfalls of BEPS
The potential impact on Florida-based marina and boating industries of a post-embargo Cuba: an analysis of geographic, physical, policy and industry trends
The information in this Technical Paper addresses the future of the US-Cuban marina and recreational
boating industries from the geographic, physical, policy making and economic perspectives for a post-embargo Cuba.
Each individual paper builds on the presentations made at the workshop, the information obtained in the subsequent trip
to Cuba and presents in detailed form information which we hope is useful to all readers. (147pp.
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