1,066 research outputs found
Consumer preferences and the National Treatment Principle: emerging environmental regulations prompt a new look at an old problem
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
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
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
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
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.
A modified coordinated reorder procedure under aggregate investment and service constraints using optimal policiy surfaces
Enamel malformations associated with a defined dentin sialophosphoprotein mutation in two families
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90129/1/EOS_874_sm_FigS1-9.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/90129/2/j.1600-0722.2011.00874.x.pd
The Estimation of Cable Input Impedance Through Analytical Techniques
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
Enamel proteins and proteases in Mmp20 and Klk4 null and double‐null mice
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90347/1/j.1600-0722.2011.00866.x.pd
The effect of fluoride on enamel and dentin formation in the uremic rat incisor
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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