3,677 research outputs found

    Minding the Gap: Bias, Soft Structures, and the Double Life of Social Norms

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    We argue that work on norms provides a way to move beyond debates between proponents of individualist and structuralist approaches to bias, oppression, and injustice. We briefly map out the geography of that debate before presenting Charlotte Witt’s view, showing how her position, and the normative ascriptivism at its heart, seamlessly connects individuals to the social reality they inhabit. We then describe recent empirical work on the psychology of norms and locate the notions of informal institutions and soft structures with respect to it. Finally, we argue that the empirical resources enrich Witt’s ascriptivism, and that the resulting picture shows theorists need not, indeed should not, choose between either the individualist or structuralist camp

    On nonlinear Alfv\'en-cyclotron waves in multi-species plasma

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    Large-amplitude Alfv\'en waves are ubiquitous in space plasmas and a main component of magnetohydrodynamic (MHD) turbulence in the heliosphere. As pump waves they are prone to parametric instability by which they can generate cyclotron and acoustic daughter waves. Here we revisit a related process within the framework of the multi-fluid equations for a plasma consisting of many species. The nonlinear coupling of the Alfv\'en wave to acoustic waves is studied, and a set of compressive and coupled wave equations for the transverse magnetic field and longitudinal electric field is derived for waves propagating along the mean-field direction. It turns out that slightly compressive Alfv\'en waves exert, through induced gyro-radius and kinetic-energy modulations, an electromotive force on the particles in association with a longitudinal electric field, which has a potential that is given by the gradient of the transverse kinetic energy of the particles gyrating about the mean field. This in turn drives electric fluctuations (sound and ion-acoustic waves) along the mean magnetic field, which can nonlinearly react back on the transverse magnetic field. Mutually coupled Alfv\'en-cyclotron-acoustic waves are thus excited, a nonlinear process that can drive a cascade of wave energy in the plasma and may generate compressive microturbulence. These driven electric fluctuations might have consequences for the dissipation of MHD turbulence and, thus, for the heating and acceleration of particles in the solar wind.Comment: 19 pages, accepted by Journal of Plasma Physics, in press, Link: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7908294&fulltextType=RA&fileId=S002237781000054

    A Rock Physics Based Investigation of Pore Structure Variations Associated with a CO2 Flood in a Clastic Reservoir, Delhi, LA

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    The permeability in siliclastic rocks can vary due to different pore geometries. The pore properties of a formation can also have significant effects on reflection coefficient. The pore structure of clastic rock may be predicted from a wave reflection using mathematical models. Biot-Gassmann and Sun’s equations are examples of two models which were used in this research to quantify the pore property. The purpose of this thesis is to measure variations in porosity and permeability using 3-D time lapsed seismic during a CO_(2) flood. CO_(2) sequestration EOR will most likely cause permanent diagenetic effects that will alter pore geometry and permeability. This research shows compelling evidence that the pore structure changes in an active CO_(2) flood at the Delhi Holt-Bryant reservoir can be measured with acoustic data. The pore property change is measured by using the Baechle ratio, the Gassmann model, and the Sun framework flexibility factor. The change in the pore properties of the formation also indicates a increase in the permeability of the reservoir as a result of CO_(2) interaction

    Recent Uplift of the Burica Peninsula, Panama and Costa Rica, Recorded by Marine Terraces

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    Deformation and uplift of the Burica Peninsula along the Panama-Costa Rica border results from eastward migration of the Panama Triple Junction (PTJ); the boundary between three tectonic plates. As the triple junction migrates to the southeast at ~55 mm/yr along the Middle America Trench (MAT), the Panama Fracture Zone (PFZ), separating the Cocos and Nazca plates, subducts under the Panama microplate. Differences in the thickness of the plates across the PFZ, as well as the rate and angle of subduction between the Cocos and Nazca plates, cause the Panama microplate to step up and over the Cocos plate. A flight of up to seven marine terraces are recognized on Burica, the highest of which does not exceed ~80 m. Terraces grade from thin, sediment-starved strata deposits to ~10 m thick bay-filled shelf sediments. Radiocarbon and Optical Stimulated Luminescence (OSL) ages indicate these deposits range in age from Marine Isotope Stage (MIS) 3 (45,800 ± 7,100 YBP) to latest Holocene (90 ± 50 YBP). Uplift rates calculated from terrace ages and high-precision DGPS surveys range between 2.2 mm/yr and 3.2 mm/yr. The consistent elevation of inner edges (paleo-high tide line) indicates that uplift of the Burica Peninsula is spatially uniform. The Panama microplate is being uplifted at a constant and uniform uplift rate along a north striking and eastward dipping thrust fault in response to subduction of the Cocos Ridge

    Human impacts on soil carbon dynamics of deep-rooted Amazonian forests and effect of land use change on the carbon cycle in Amazon soils

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    The main objective of these NASA-funded projects is to improve our understanding of land-use impacts on soil carbon dynamics in the Amazon Basin. Soil contains approximately one half of tropical forest carbon stocks, yet the fate of this carbon following forest impoverishment is poorly studied. Our mechanistics approach draws on numerous techniques for measuring soil carbon outputs, inputs, and turnover time in the soils of adjacent forest and pasture ecosystems at our research site in Paragominas, state of Para, Brazil. We are scaling up from this site-specific work by analyzing Basin-wide patterns in rooting depth and rainfall seasonality, the two factors that we believe should explain much of the variation in tropical soil carbons dynamics. In this report, we summarize ongoing measurements at our Paragominas study site, progress in employing new field data to understand soil C dynamics, and some surprising results from our regional, scale-up work

    Process evaluation of Derbyshire Intensive Alternatives to Custody Pilot

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    The aim of this study was to critically assess the implementation and development of the Intensive Alternatives to Custody (IAC) pilot in Derbyshire. The Ministry of Justice (MoJ) Penal Policy paper (May 2007) outlined the government’s intention to develop higher intensity community orders as an alternative to short-term custody. The IAC Order was subsequently developed and piloted, first in Derbyshire and then in six other areas.* The pilots were centrally funded until March 2011

    Generalized Geologic Map for Land-Use Planning: Trimble County, Kentucky

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    This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock

    Generalized Geologic Map for Land-Use Planning: Madison County, Kentucky

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    This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site-to-site basis. At any site, it is important to understand the characteristics of both the soils and the underlying rock
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