4,922 research outputs found
THE ORGANIC LABEL: HOW TO RECONCILE ITS MEANING WITH CONSUMER PREFERENCES
The USDA's National Organic Program (NOP), with its unified definition and labeling requirements, holds great promise for increasing commerce in and decreasing transaction costs associated with purchasing organic food. However, the label and its meaning must both be well understood and reflect the traits consumers want if this promise is to be realized. This paper reports the results of a survey and experimental auction on consumers' preferences for organic standards. On one hand, the USDA NOP's Final Rule broadly conforms to consumer preferences regarding what practices should or should not be permitted in organic production and processing. Consumers support a strict definition of organic in general, opposing the use of a variety of practices historically banned by organic certifiers. For example, both the survey and auction methods found that consumers support the banning of Genetically Modified Organisms in organic food and are willing to pay a premium to avoid them. Consumers are also in accord with the Final Rule's exclusion of irradiation, biosolids, growth regulators, etc. On the other hand, the survey and auction results reveal a lack of understanding of the label's meaning as well as a disconnect between the label's function (detailing acceptable production practices) and consumers' stated motivations for buying organic (e.g., support for a local sustainable food system). Implications of these findings for decision makers in policy and industry are discussed. Of particular focus will be the role of these agents in promoting products that allow consumers to purchase items that reflect and support these values.Consumer/Household Economics,
CONSUMER PREFERENCES FOR ORGANIC STANDARDS: GUIDING DEMAND-EXPANSION STRATEGIES FOR ORGANIC FOOD
Consumer/Household Economics,
Resistive Magnetohydrodynamic Equilibria in a Torus
It was recently demonstrated that static, resistive, magnetohydrodynamic
equilibria, in the presence of spatially-uniform electrical conductivity, do
not exist in a torus under a standard set of assumed symmetries and boundary
conditions. The difficulty, which goes away in the ``periodic straight cylinder
approximation,'' is associated with the necessarily non-vanishing character of
the curl of the Lorentz force, j x B. Here, we ask if there exists a spatial
profile of electrical conductivity that permits the existence of zero-flow,
axisymmetric r esistive equilibria in a torus, and answer the question in the
affirmative. However, the physical properties of the conductivity profile are
unusual (the conductivity cannot be constant on a magnetic surface, for
example) and whether such equilibria are to be considered physically possible
remains an open question.Comment: 17 pages, 4 figure
Vitis riparia Michx.
https://thekeep.eiu.edu/herbarium_specimens_byname/19457/thumbnail.jp
Vitis riparia Michx.
https://thekeep.eiu.edu/herbarium_specimens_byname/19457/thumbnail.jp
Thickness dependence of spin-orbit torques generated by WTe2
We study current-induced torques in WTe2/permalloy bilayers as a function of
WTe2 thickness. We measure the torques using both second-harmonic Hall and
spin-torque ferromagnetic resonance measurements for samples with WTe2
thicknesses that span from 16 nm down to a single monolayer. We confirm the
existence of an out-of-plane antidamping torque, and show directly that the
sign of this torque component is reversed across a monolayer step in the WTe2.
The magnitude of the out-of-plane antidamping torque depends only weakly on
WTe2 thickness, such that even a single-monolayer WTe2 device provides a strong
torque that is comparable to much thicker samples. In contrast, the
out-of-plane field-like torque has a significant dependence on the WTe2
thickness. We demonstrate that this field-like component originates
predominantly from the Oersted field, thereby correcting a previous inference
drawn by our group based on a more limited set of samples.Comment: 8 pages, 8 figure
Anterior Prefrontal Cortex Contributes to Action Selection through Tracking of Recent Reward Trends
The functions of prefrontal cortex remain enigmatic, especially for its anterior sectors, putatively ranging from planning to self-initiated behavior, social cognition, task switching, and memory. A predominant current theory regarding the most anterior sector, the frontopolar cortex (FPC), is that it is involved in exploring alternative courses of action, but the detailed causal mechanisms remain unknown. Here we investigated this issue using the lesion method, together with a novel model-based analysis. Eight patients with anterior prefrontal brain lesions including the FPC performed a four-armed bandit task known from neuroimaging studies to activate the FPC. Model-based analyses of learning demonstrated a selective deficit in the ability to extrapolate the most recent trend, despite an intact general ability to learn from past rewards. Whereas both brain-damaged and healthy controls used comparisons between the two most recent choice outcomes to infer trends that influenced their decision about the next choice, the group with anterior prefrontal lesions showed a complete absence of this component and instead based their choice entirely on the cumulative reward history. Given that the FPC is thought to be the most evolutionarily recent expansion of primate prefrontal cortex, we suggest that its function may reflect uniquely human adaptations to select and update models of reward contingency in dynamic environments
Seismometer Detection of Dust Devil Vortices by Ground Tilt
We report seismic signals on a desert playa caused by convective vortices and
dust devils. The long-period (10-100s) signatures, with tilts of ~10
radians, are correlated with the presence of vortices, detected with nearby
sensors as sharp temporary pressure drops (0.2-1 mbar) and solar obscuration by
dust. We show that the shape and amplitude of the signals, manifesting
primarily as horizontal accelerations, can be modeled approximately with a
simple quasi-static point-load model of the negative pressure field associated
with the vortices acting on the ground as an elastic half space. We suggest the
load imposed by a dust devil of diameter D and core pressure {\Delta}Po is
~({\pi}/2){\Delta}PoD, or for a typical terrestrial devil of 5 m diameter
and 2 mbar, about the weight of a small car. The tilt depends on the inverse
square of distance, and on the elastic properties of the ground, and the large
signals we observe are in part due to the relatively soft playa sediment and
the shallow installation of the instrument. Ground tilt may be a particularly
sensitive means of detecting dust devils. The simple point-load model fails for
large dust devils at short ranges, but more elaborate models incorporating the
work of Sorrells (1971) may explain some of the more complex features in such
cases, taking the vortex winds and ground velocity into account. We discuss
some implications for the InSight mission to Mars.Comment: Contributed Article for Bulletin of the Seismological Society of
America, Accepted 29th August 201
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