7,950 research outputs found
Precaution and Protectionism: GM Food and the WTO
The dispute between the US and EU over GM foods at the WTO is examined in terms of the issues it raises about protectionism and environmental protection and precaution. The issue of whether GM, GM Derived and Non-GM foods are equivalent to each other is examined using data from a national choice modelling study in the UK. These categories of food are critical since they underpin the EU's new food labelling regime which it hoped would defuse the WTO dispute. The results are analysed using a Bayesian mixed logit model which allows greater flexibility in the modelling of preference distributions. This is particularly crucial where, as in this case, bi-modal distributions are identified with some indifferent or mildly averse to GM foodtypes while others are strongly averse. A strong finding of the analysis is that people treat ingredients derived from GM crops (but free from altered DNA) as equivalent to GM ingredients. This supports a labelling regime based on process rather than simply product and suggests considerable consumer benefits from the EU's new GM labelling regime.GM food, mixed logit, WTP, Bayesian, WTO, International Relations/Trade, C11, C24, C25, D12, Q18,
Precaution and Protectionism: 'Likeness' and GM Food at the WTO
The dispute between the US and EU over GM foods at the WTO is examined in terms of the issues it raises about protectionism, environmental protection and precaution. The issue of whether GM, GM Derived and Non-GM foods are equivalent to each other is examined using data from a national choice modelling study in the UK. These categories of food are critical since they underpin the EU's new food labelling regime which it hoped would defuse the WTO dispute. The results are analysed using a Bayesian mixed logit model which allows greater flexibility in the modelling of preference distributions than that allowed through classical estimation. The Bayesian approach allows the use of censored normal and Johnson's SB distributions which can accommodate a bounded distribution with a probability mass point at zero (i.e. indifference). This is particularly important where, as in the case of GM food, we may expect some to be indifferent to the food whilst others dislike it, some strongly so. The results indicate bi-modal distributions regarding GM foodtypes, with some indifferent or mildly averse to GM foodtypes and others are strongly averse. A strong finding of the analysis is that most people treat ingredients derived from GM crops (but free from altered DNA) as equivalent to GM ingredients. This supports a labelling regime based on process rather than simply product and suggests considerable consumer benefits from the EU's new GM labelling regime.GM food, mixed logit, WTP, Bayesian, WTO, International Relations/Trade, Q51, Q55, Q56, Q58,
ASIAN DEMOGRAPHIC TRANSITION: AN INSTRUMENTAL-VARIABLES PANEL APPROACH
We examine patterns in fertility during the demographic transition using a panel data set across 25 Asian countries for 1975-2003. The adult female literacy rate is used as an instrumental variable for the endogenous female labor force participation rate, which has been unsolved in the population literature. The preliminary panel data analysis suggests that relative cohort size is significant in explaining the decline in fertility before controlling for simultaneity bias. This result, however, may be spurious. After considering the instrumental variables estimation in the panel data structure, the age structure variable no longer plays a dominant role in explaining declining fertility rates in many Asian countries. Systematic differences were found between East and South Asia. A policy implication in South Asia is that development may reduce fertility directly through increasing income rather than indirectly through a change in female labor force participation or urbanization. In East Asia, the indirect effects dominate.Fertility, Easterlin hypothesis, Transition Economies, Relative Cohort Size, Age Structure
Fertility in Sub-Saharan African Countries with Consideration to Health and Poverty
Fertility has begun to fall in Sub-Saharan Africa but it remains high on average and particularly for a few countries. This paper examines African fertility using a panel data set of 47 Sub-Saharan countries between 1962 and 2003. Fixed and random country effect estimates are made in models where the explanatory variables are suggested by the theory of the demographic transition as modified by Caldwell. Special attention is paid to the economic status of women, urbanization, the poverty level, and the health of the population including total health expenditures and the prevalence of HIV/AIDS. The results support Caldwell’s hypothesis and are generally supportive of hypothesis that a fertility transition is occurring. HIV/AIDS is found to have a negative impact on fertility.Africa, infant mortality, fertility, poverty, health
Fractional Chern insulator edges and layer-resolved lattice contacts
Fractional Chern insulators (FCIs) realized in fractional quantum Hall
systems subject to a periodic potential are topological phases of matter for
which space group symmetries play an important role. In particular, lattice
dislocations in an FCI can host topology-altering non-Abelian topological
defects, known as genons. Genons are of particular interest for their potential
application to topological quantum computing. In this work, we study FCI edges
and how they can be used to detect genons. We find that translation symmetry
can impose a quantized momentum difference between the edge electrons of a
partially-filled Chern band. We propose {\it layer-resolved lattice contacts},
which utilize this momentum difference to selectively contact a particular FCI
edge electron. The relative current between FCI edge electrons can then be used
to detect the presence of genons in the bulk FCI. Recent experiments have
demonstrated graphene is a viable platform to study FCI physics. We describe
how the lattice contacts proposed here could be implemented in graphene subject
to an artificial lattice, thereby outlining a path forward for experimental
dectection of non-Abelian topological defects.Comment: 5+7 pages, 10 figures, v2: modified figure
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Evolutionary Signatures In The Formation Of Low-Mass Protostars. II. Toward Reconciling Models And Observations
A long-standing problem in low-mass star formation is the "luminosity problem," whereby protostars are underluminous compared to the accretion luminosity expected both from theoretical collapse calculations and arguments based on the minimum accretion rate necessary to form a star within the embedded phase duration. Motivated by this luminosity problem, we present a set of evolutionary models describing the collapse of low-mass, dense cores into protostars. We use as our starting point the evolutionary model following the inside-out collapse of a singular isothermal sphere as presented by Young & Evans. We calculate the radiative transfer of the collapsing core throughout the full duration of the collapse in two dimensions. From the resulting spectral energy distributions, we calculate standard observational signatures (L(bol), T(bol), L(bol)/L(smm)) to directly compare to observations. We incorporate several modifications and additions to the original Young & Evans model in an effort to better match observations with model predictions; we include (1) the opacity from scattering in the radiative transfer, (2) a circumstellar disk directly in the two-dimensional radiative transfer, (3) a two-dimensional envelope structure, taking into account the effects of rotation, (4) mass-loss and the opening of outflow cavities, and (5) a simple treatment of episodic mass accretion. We find that scattering, two-dimensional geometry, mass-loss, and outflow cavities all affect the model predictions, as expected, but none resolve the luminosity problem. On the other hand, we find that a cycle of episodic mass accretion similar to that predicted by recent theoretical work can resolve this problem and bring the model predictions into better agreement with observations. Standard assumptions about the interplay between mass accretion and mass loss in our model give star formation efficiencies consistent with recent observations that compare the core mass function and stellar initial mass function. Finally, the combination of outflow cavities and episodic mass accretion reduces the connection between observational class and physical stage to the point where neither of the two commonly used observational signatures (T(bol) and L(bol)/L(smm)) can be considered reliable indicators of physical stage.NASA 1224608, 1288664, 1288658, RSA 1377304, NNX 07-AJ72GNSF AST0607793UT Austin University Continuing FellowshipAstronom
Esophageal perforation following anterior cervical spine surgery: Case report and review of the literature
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