1,066 research outputs found

    Consumer preferences and the National Treatment Principle: emerging environmental regulations prompt a new look at an old problem

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    Should consumers’ preference for ‘green’ products help justify,from a WTO perspective, emerging regulations such as restrictions on trade in non-sustainable biofuels? Despite the role consumer preferences have played in WTO disputes, in association with the ‘ like ’ products concept, there has not been enough focused examination of their specific influence, particularly in disputes on ethical public policy issues, such as environmental or health regulations. To this end, this paper examines key GATT Article III disputes, pointing out that they included attempts both to measure, and also to interpret, consumer preferences. The latter approach becomes more tempting when consumer preferences are difficult to measure; import bans or restrictions associated with ethical public policy regulations can bring about such a situation. A hypothetical dispute about EC biofuels sustainability criteria demonstrates this problem. Options to make the concept of consumer preferences more coherent include limitations on how they can be invoked, and an increased commitment to capturing them through measurement

    Trade and competition interlinkages: The case of Telecom

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    The commitments entered into in the WTO Telecommunications Agreement include a fairly elaborate set of principles designed to encourage and protect competition in this newly liberalising market. This paper analyses these commitments, to see first of all what they mean for the telecommunications sector. In addition, the paper inquires after the implications of these additional commitments for the ongoing debate in WTO whether a more encompassing agreement ought to be drafted on competition law

    The Na+/Ca2+, K+ exchanger NCKX4 is required for efficient cone-mediated vision

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    Calcium (Ca2+) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na+/Ca2+, K+ exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival

    Spatio-temporal structure of cell distribution in cortical Bone Multicellular Units: a mathematical model

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    Bone remodelling maintains the functionality of skeletal tissue by locally coordinating bone-resorbing cells (osteoclasts) and bone-forming cells (osteoblasts) in the form of Bone Multicellular Units (BMUs). Understanding the emergence of such structured units out of the complex network of biochemical interactions between bone cells is essential to extend our fundamental knowledge of normal bone physiology and its disorders. To this end, we propose a spatio-temporal continuum model that integrates some of the most important interaction pathways currently known to exist between cells of the osteoblastic and osteoclastic lineage. This mathematical model allows us to test the significance and completeness of these pathways based on their ability to reproduce the spatio-temporal dynamics of individual BMUs. We show that under suitable conditions, the experimentally-observed structured cell distribution of cortical BMUs is retrieved. The proposed model admits travelling-wave-like solutions for the cell densities with tightly organised profiles, corresponding to the progression of a single remodelling BMU. The shapes of these spatial profiles within the travelling structure can be linked to the intrinsic parameters of the model such as differentiation and apoptosis rates for bone cells. In addition to the cell distribution, the spatial distribution of regulatory factors can also be calculated. This provides new insights on how different regulatory factors exert their action on bone cells leading to cellular spatial and temporal segregation, and functional coordination.Comment: 14 pages, 5 figures; v2: Completed model description after Eq. (16), clarified discussion/description after Eq. (23), between Eqs. (29)-(31), and in 2nd bullet point in conclusion

    Investigation of bone resorption within a cortical basic multicellular unit using a lattice-based computational model

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    In this paper we develop a lattice-based computational model focused on bone resorption by osteoclasts in a single cortical basic multicellular unit (BMU). Our model takes into account the interaction of osteoclasts with the bone matrix, the interaction of osteoclasts with each other, the generation of osteoclasts from a growing blood vessel, and the renewal of osteoclast nuclei by cell fusion. All these features are shown to strongly influence the geometrical properties of the developing resorption cavity including its size, shape and progression rate, and are also shown to influence the distribution, resorption pattern and trajectories of individual osteoclasts within the BMU. We demonstrate that for certain parameter combinations, resorption cavity shapes can be recovered from the computational model that closely resemble resorption cavity shapes observed from microCT imaging of human cortical bone.Comment: 17 pages, 11 figures, 1 table. Revised version: paper entirely rewritten for a more biology-oriented readership. Technical points of model description now in Appendix. Addition of two new figures (Fig. 5 and Fig. 9) and removal of former Fig.

    The Estimation of Cable Input Impedance Through Analytical Techniques

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    In this paper, two analytical techniques for computing the input impedance of cables are introduced. Given the pivotal role of the SMA connector in altering cable input impedance, it is essential to account for the significant effect of the connector in the impedance calculations. This effect is addressed through the use of two models for the connector, namely the circuit model and the cascade model. These analytical techniques can be applied to various cables, provided that the impedance of the cable up to the connector is known, and the impact of the connector on the input impedance is appropriately considered by the models

    The effect of fluoride on enamel and dentin formation in the uremic rat incisor

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    Renal impairment in children is associated with tooth defects that include enamel pitting and hypoplasia. However, the specific effects of uremia on tooth formation are not known. In this study, we used rat mandibular incisors, which continuously erupt and contain all stages of tooth formation, to characterize the effects of uremia on tooth formation. We also tested the hypothesis that uremia aggravates the fluoride (F)-induced changes in developing teeth. Rats were subjected to a two-stage 5/6 nephrectomy or sham operation and then exposed to 0 (control) or 50 ppm NaF in drinking water for 14 days. The effects of these treatments on food intake, body growth rate, and biochemical serum parameters for renal function and calcium metabolism were monitored. Nephrectomy reduced food intake and weight gain. Intake of F by nephrectomized rats increased plasma F levels twofold and further decreased food intake and body weight gain. Uremia affected formation of dentin and enamel and was more extensive than the effect of F alone. Uremia also significantly increased predentin width and induced deposition of large amounts of osteodentin-like matrix-containing cells in the pulp chamber. In enamel formation, the cells most sensitive to uremia were the transitional-stage ameloblasts. These data demonstrate that intake of F by rats with reduced renal function impairs F clearance from the plasma and aggravates the already negative effects of uremia on incisor tooth development
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