367 research outputs found

    Les Priacanthidae (Teleostei, Perciformes) des Sables de Lede (Éocène moyen, Belgique): ostéologie et otolithes

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    The osteology of the fossil priacanthid Pristigenys rutoti (= P. caduca) (Teleostei, Percoidei) from the Sands of Lede (marine Middle Eocene, Belgium) is described in details thanks to a nearly complete specimen with a skull preserved in volume and to other samples with isolated bones. A new species, Pristigenys hermani, also from the Sands of Lede, is erected on the basis of isolated bones and otoliths. The two species are compared together. It is shown that the skeletal elements and the otoliths of Pristigenys dentifer from the Eocene of England are identical to the homologous pieces of P. rutoti. The English species is put into synonymy of the Belgian species which has the priority. The evolution of the sagitta within Priacanthidae is discussed

    Investigation of defect cavities formed in three-dimensional woodpile photonic crystals

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    We report the optimisation of optical properties of single defects in three-dimensional (3D) face-centred-cubic (FCC) woodpile photonic crystal (PC) cavities by using plane-wave expansion (PWE) and finite-difference time-domain (FDTD) methods. By optimising the dimensions of a 3D woodpile PC, wide photonic band gaps (PBG) are created. Optical cavities with resonances in the bandgap arise when point defects are introduced in the crystal. Three types of single defects are investigated in high refractive index contrast (Gallium Phosphide-Air) woodpile structures and Q-factors and mode volumes (VeffV_{eff}) of the resonant cavity modes are calculated. We show that, by introducing an air buffer around a single defect, smaller mode volumes can be obtained. We demonstrate high Q-factors up to 700000 and cavity volumes down to Veff<0.2(λ/n)3V_{eff}<0.2(\lambda/n)^3. The estimates of QQ and VeffV_{eff} are then used to quantify the enhancement of spontaneous emission and the possibility of achieving strong coupling with nitrogen-vacancy (NV) colour centres in diamond.Comment: 12 pages, 11 figure

    Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

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    We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed

    Modelling Defect Cavities Formed in Inverse Three-Dimensional Rod-Connected Diamond Photonic Crystals

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    Defect cavities in 3D photonic crystal can trap and store light in the smallest volumes allowable in dielectric materials, enhancing non-linearities and cavity QED effects. Here, we study inverse rod-connected diamond (RCD) crystals containing point defect cavities using plane-wave expansion and finite-difference time domain methods. By optimizing the dimensions of the crystal, wide photonic band gaps are obtained. Mid-bandgap resonances can then be engineered by introducing point defects in the crystal. We investigate a variety of single spherical defects at different locations in the unit cell focusing on high-refractive-index contrast (3.3:1) inverse RCD structures; quality factors (Q-factors) and mode volumes of the resonant cavity modes are calculated. By choosing a symmetric arrangement, consisting of a single sphere defect located at the center of a tetrahedral arrangement, mode volumes < 0.06 cubic wavelengths are obtained, a record for high index cavities.Comment: 7 pages, 8 figure

    Influence of applying different units of measurement on reporting antimicrobial consumption data for pig farms

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    Background: Antimicrobial use in livestock is one of the factors contributing to selection and spread of resistant microorganisms in the environment. National ve

    Shared Music Listening: Walking alongside adolescents with experiences of trauma

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    Background: Shared listening of music has been widely explored in the field of music therapy, with some application to working with adolescents with experiences of trauma. However, there is a paucity of research investigating its potential application in school counselling settings. Aims: This article therefore presents the findings of a hermeneutic phenomenological pilot study exploring the viability of integrating shared listening of music into guidance officer (school counsellor) practice. Method: Semi- structured interviews were conducted with music therapists and a school counsellor who had utilised this intervention extensively in their practice. Results: The thematic analysis of findings revealed that shared listening of music represents an accessible and flexible intervention that can aid in developing emotional resilience and mood regulation for adolescents with experiences of trauma. Conclusion: The discussion highlights the importance of openness and authenticity on behalf of the therapist, and places emphasis on letting the young person lead the process, making for impactful and meaningful therapeutic engagement

    Is international agricultural research a global public good? : The case of rice biofortification

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    The status of international agricultural research as a global public good (GPG) has been widely accepted since the Green Revolution of the 1960s and 1970s. While the term was not used at the time of its creation, the Consultative Group on International Agricultural Research (CGIAR) system that evolved at that time has been described as a 'prime example of the promise, performance and perils of an international approach to providing GPGs'. Contemporary literature on international agricultural research as a GPG tends to support this view and focuses on how to operationalize the concept. This paper adopts a different starting point and questions this conceptualization of the CGIAR and its outputs. It questions the appropriateness of such a 'neutral' concept to a system born of the imperatives of Cold War geopolitics, and shaped by a history of attempts to secure its relevance in a changing world. This paper draws on a multi-sited, ethnographic study of a research effort highlighted by the CGIAR as an exemplar of GPG-oriented research. Behind the ubiquitous language of GPGs, 'partnership' and 'consensus', however, new forms of exclusion and restriction are emerging within everyday practice, reproducing North-South inequalities and undermining the ability of these programmes to respond to the needs of projected beneficiaries

    Guidance on the Selection of Appropriate Indicators for Quantification of Antimicrobial Usage in Humans and Animals

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    An increasing variety of indicators of antimicrobial usage has become available in human and veterinary medicine, with no consensus on the most appropriate indicators to be used. The objective of this review is therefore to provide guidance on the selection of indicators, intended for those aiming to quantify antimicrobial usage based on sales, deliveries or reimbursement data. Depending on the study objective, different requirements apply to antimicrobial usage quantification in terms of resolution, comprehensiveness, stability over time, ability to assess exposure and comparability. If the aim is to monitor antimicrobial usage trends, it is crucial to use a robust quantification system that allows stability over time in terms of required data and provided output; to compare usage between different species or countries, comparability must be ensured between the different populations. If data are used for benchmarking, the system comprehensiveness is particularly crucial, while data collected to study the association between usage and resistance should express the exposure level and duration as a measurement of the exerted selection pressure. Antimicrobial usage is generally described as the number of technical units consumed normalized by the population at risk of being treated in a defined period. The technical units vary from number of packages to number of individuals treated daily by adding different levels of complexity such as daily dose or weight at treatment. These technical units are then related to a description of the population at risk, based either on biomass or number of individuals. Conventions and assumptions are needed for all of these calculation steps. However, there is a clear lack of standardization, resulting in poor transparency and comparability. By combining study requirements with available approaches to quantify antimicrobial usage, we provide suggestions on the most appropriate indicators and data sources to be used for a given study objective
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