510 research outputs found

    Purcell factor for point-like dipolar emitter coupling to 2D-plasmonic waveguides

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    We theoretically investigate the spontaneous emission of a point--like dipolar emitter located near a two--dimensional (2D) plasmonic waveguide of arbitrary form. We invoke an explicite link with the density of modes of the waveguide describing the electromagnetic channels into which the emitter can couple. We obtain a closed form expression for the coupling to propagative plasmon, extending thus the Purcell factor to plasmonic configurations. Radiative and non-radiative contributions to the spontaneous emission are also discussed in details

    How Much Longer Will it Take? A Ten-year Review of the Implementation of United Nations General Assembly Resolutions 61/105, 64/72 and 66/68 on the Management of Bottom Fisheries in Areas Beyond National Jurisdiction

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    The United Nations General Assembly (UNGA) in 2002 adopted the first in a series of resolutions regarding the conservation of biodiversity in the deep sea. Prompted by seriousconcerns raised by scientists, non-governmental organizations (NGOs) and numerous States,these resolutions progressively committed States to act both individually and through regional fishery management organizations (RFMOs) to either manage bottom fisheries in areas beyond national jurisdiction to prevent significant adverse impacts on deep-sea species, ecosystems and biodiversity or else prohibit bottom fishing from taking place.Ten years have passed since the adoption of resolution 61/105 in 2006, calling on States to take a set of specific actions to manage bottom fisheries in areas beyond national jurisdiction to protect vulnerable marine ecosystems (VMEs) from the adverse impacts of bottom fishing and ensure the sustainability of deep-sea fish stocks. Despite the considerable progress by some RFMOs, there remain significant gaps in the implementation of key elements and commitments in the resolutions. The Deep Sea Conservation Coalition (DSCC) has prepared this report to assist the UNGA in its review in 2016 and to address the following question: How effectively have the resolutions been implemented

    A Beginner's Guide to the Understanding of Integral Continuum Approaches Applied to the Formulation of Flow and Transport Equation in Porous Media Systems

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    Standard approaches exist in many fields of science and engineering for the description of multiphase flow and transport phenomena in porous media; we focus on multiphase subsurface systems in this work. The common approach to the formulation of balance equations for such systems is limited by several inconsistencies and approximations that affect the accuracy of these formulations in a manner and to an extent that is not well understood. The constitutive relations traditionally applied have evolved under restrictive assumptions and conditions yet are routinely applied to systems that are much different. Additionally, paradoxes exist in the commonly applied constitutive relations. The integral continuum approach yields a complete formal averaging formulation of mass, momentum, and energy balance laws for volumes, interfaces, and contact lines. This formulation can be constrained by entropy balance relations to yield a more complete and thermodynamically consistent description of multiphase flow and transport phenomena than is available through standard approaches. In this work, we:(1) review the standard approach for modeling multiphase flow and transport, noting inconsistencies and limitations; (2) outline the integral continuum approach at the microscale and macroscale; (4) compare and contrast the balance equations resulting from the approaches; (5) derive integral continuum balance equations, formally averaged from th emicroscale to the macroscale, for volumes, interfaces, and contact lines; (6) apply the integral continuum balance equations to a two fluid-phase subsurface system; (7) constrain the application thermodynamically utilizing the methodology of Coleman and Noll [1963]; and (8) comment on the unresolved issues facing the application of integral continuum approaches, noting promising approaches for the resolution of these issues.Master of Science in Environmental Engineerin

    Polarization state of the optical near-field

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    The polarization state of the optical electromagnetic field lying several nanometers above complex dielectric structures reveals the intricate light-matter interaction that occurs in this near-field zone. This information can only be extracted from an analysis of the polarization state of the detected light in the near-field. These polarization states can be calculated by different numerical methods well-suited to near--field optics. In this paper, we apply two different techniques (Localized Green Function Method and Differential Theory of Gratings) to separate each polarisation component associated with both electric and magnetic optical near-fields produced by nanometer sized objects. The analysis is carried out in two stages: in the first stage, we use a simple dipolar model to achieve insight into the physical origin of the near-field polarization state. In the second stage, we calculate accurate numerical field maps, simulating experimental near-field light detection, to supplement the data produced by analytical models. We conclude this study by demonstrating the role played by the near-field polarization in the formation of the local density of states.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.

    Unfinished Business: a Review of the Implementation of the Provisions of United Nations General Assembly Resolutions 61/105 and 64/72, Related to the Management of Bottom Fisheries in Areas Beyond National Jurisdiction

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    In 2006 the General Assembly adopted resolution 61/105, based on a compromise proposal offered by deep-sea fishing nations, which committed States and regional fisheries management organisations [RFMOs] to take specific measures to protect vulnerable marine ecosystems [VMEs] from the adverse impacts of bottom fisheries in the high seas and to ensure the longterm sustainability of deep-sea fish stocks. These measures included conducting impact assessments to determine whether significant adverse impacts[SAIs] to VMEs would occur, managing fisheries to prevent SAIs on VMEs, and closing areas of the high seas to bottom fishing where VMEs are known or likely to occur, unless regulations are in place to prevent SAIs and to manage sustainably deep-sea fish stocks. Based on a review in 2009 of the actions taken by States and RFMOS, the UNGA adoptedresolution 64/72 that reaffirmed resolution 61/105 and strengthened the call for action through committing States, inter alia, to ensure that vessels do not engage in bottom fishing until impact assessments have been carried out and to not authorise bottom fishing activities until the measures in resolutions 64/72 and 61/105 have been adopted andimplemented
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