699 research outputs found

    Europe\u27s Evolving Regulatory Strategy for GMOs --- The Issue of Consistncy with WTO Law: of Kine and Brine

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    This Essay deals with one question: If challenged, how would regulatory restrictions on genetically modified organisms ( GMOs ) be judged by a World Trade Organization ( WTO ) adjudicating body. Many of the controversies about the effect of WTO law on domestic regulation have been influenced by the view that the law as it stands may well impede the ability of governments to regulate new and uncertain risks to health and the environment. The result in the Beef Hormones case is often cited for this proposition. In this Essay we aim to show that, contrary to an increasingly widespread popular perception, if WTO law is properly interpreted, GMO-related measures, where non-discriminatory against other WTO Members, can pass the test of consistency with even the most stringent of relevant WTO rules

    Phase separation and rotor self-assembly in active particle suspensions

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    Adding a non-adsorbing polymer to passive colloids induces an attraction between the particles via the `depletion' mechanism. High enough polymer concentrations lead to phase separation. We combine experiments, theory and simulations to demonstrate that using active colloids (such as motile bacteria) dramatically changes the physics of such mixtures. First, significantly stronger inter-particle attraction is needed to cause phase separation. Secondly, the finite size aggregates formed at lower inter-particle attraction show unidirectional rotation. These micro-rotors demonstrate the self assembly of functional structures using active particles. The angular speed of the rotating clusters scales approximately as the inverse of their size, which may be understood theoretically by assuming that the torques exerted by the outermost bacteria in a cluster add up randomly. Our simulations suggest that both the suppression of phase separation and the self assembly of rotors are generic features of aggregating swimmers, and should therefore occur in a variety of biological and synthetic active particle systems.Comment: Main text: 6 pages, 5 figures. Supplementary information: 5 pages, 4 figures. Supplementary movies available from httP://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1116334109/-/DCSupplementa

    Being Healthy: a Grounded Theory Study of Help Seeking Behaviour among Chinese Elders living in the UK

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    The health of older people is a priority in many countries as the world’s population ages. Attitudes towards help seeking behaviours in older people remain a largely unexplored field of research. This is particularly true for older minority groups where the place that they have migrated to presents both cultural and structural challenges. The UK, like other countries,has an increasingly aging Chinese population about who relatively little is known. This study used a qualitative grounded theory design following the approach of Glaser (1978). Qualitative data were collected using semi-structured interviews with 33 Chinese elders who were aged between 60 and 84, using purposive and theoretical sampling approaches. Data were analysed using the constant comparative method until data saturation occurred and a substantive theory was generated. ‘Being healthy’ (the core category) with four interrelated categories: self-management, normalizing/minimizing, access to health services, and being cured form the theory. The theory was generated around the core explanations provided by participants and Chinese elders’ concerns about health issues they face in their daily life. We also present data about how they direct their health-related activities towards meeting their physical and psychological goals of being healthy. Their differential understanding of diseases and a lack of information about health services were potent predictors of non�help seeking and ‘self’ rather than medical management of their illnesses. This study highlights the need for intervention and health support for Chinese elders

    Europe\u27s Evolving Regulatory Strategy for GMOs – The Issue of Consistency with WTO Law: Of Kine and Brine

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    This Essay deals with one question: If challenged, how would regulatory restrictions on genetically modified organisms ( GMOs ) be judged by a World Trade Organization ( WTO ) adjudicating body. Many of the controversies about the effect of WTO law on domestic regulation have been influenced by the view that the law as it stands may well impede the ability of governments to regulate new and uncertain risks to health and the environment. The result in the Beef Hormones case ( Hormones case ) is often cited for this proposition. In this Essay we aim to show that, contrary to an increasingly widespread popular perception, if WTO law is properly interpreted, GMO-related measures, where non-discriminatory against other WTO Members, can pass the test of consistency with even the most stringent of relevant WTO rules

    Active and driven hydrodynamic crystals

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    Motivated by the experimental ability to produce monodisperse particles in microfluidic devices, we study theoretically the hydrodynamic stability of driven and active crystals. We first recall the theoretical tools allowing to quantify the dynamics of elongated particles in a confined fluid. In this regime hydrodynamic interactions between particles arise from a superposition of potential dipolar singularities. We exploit this feature to derive the equations of motion for the particle positions and orientations. After showing that all five planar Bravais lattices are stationary solutions of the equations of motion, we consider separately the case where the particles are passively driven by an external force, and the situation where they are self-propelling. We first demonstrate that phonon modes propagate in driven crystals, which are always marginally stable. The spatial structure of the eigenmodes depend solely on the symmetries of the lattices, and on the orientation of the driving force. For active crystals, the stability of the particle positions and orientations depends not only on the symmetry of the crystals but also on the perturbation wavelengths and on the crystal density. Unlike unconfined fluids, the stability of active crystals is independent of the nature of the propulsion mechanism at the single particle level. The square and rectangular lattices are found to be linearly unstable at short wavelengths provided the volume fraction of the crystals is high enough. Differently, hexagonal, oblique, and face-centered crystals are always unstable. Our work provides a theoretical basis for future experimental work on flowing microfluidic crystals.Comment: 10 pages, 10 figure

    Periodic and Quasiperiodic Motion of an Elongated Microswimmer in Poiseuille Flow

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    We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow for different flow geometries. When moving between two parallel plates or in a cylindrical microchannel, the swimmer performs either periodic swinging or periodic tumbling motion. Although the trajectories of spherical and elongated swimmers are qualitatively similar, the swinging and tumbling frequency strongly depends on the aspect ratio of the swimmer. In channels with reduced symmetry the swimmers perform quasiperiodic motion which we demonstrate explicitely for swimming in a channel with elliptical cross section

    First Record of a Bloom of Gonyaulax monilata in Coastal Waters of Mississippi

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    Data are presented on a bloom of the toxic dinoflagellate Gonyaulax monilata in coastal waters of Florida, Alabama, Mississippi and Louisiana. This paper documents the first record of a bloom of this species in Mississippi Sound and adjacent Gulf of Mexico
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