7,764 research outputs found
To what extent would the poorest consumers nutritionally and socially benefit from a global food tax and subsidy reform ? A framed field experiment based on daily food intake
In this paper we propose a new method in experimental economics, designed to evaluate the effectiveness of public policy incentives aimed at altering consumer behaviors. We apply this method to wide-ranging policies on food prices, which use subsidies to increase the consumption of healthy products and taxes to reduce that of unhealthy ones. Our protocol allows for observation of an individual’s daily food consumption before and after the policy. We examine two separate policies: the one subsidizes fruit and vegetables, while the other one combines taxes and subsidies. We measure their nutritional and economic impacts on the choices of low-income French consumers, compared to a reference group. Both policies have a positive effect on the nutritional quality of food choices of the two groups but initial gaps widen, especially with the subsidies. In the low-income group this can be explained by an initially unfavorable pattern and by weaker price elasticities. The redistributive effects are therefore doubly regressive. Moreover, the individual price elasticities, that the experimental approach enables us to measure, show widely diverse behaviors. They are counter-effective for close to 40% of our sample of poor women.OBESITY;PUBLIC POLICY;SOCIAL INEQUALITIES;POVERTY;INCOME REDISTRIBUTION;REGRESSIVE TAX;INDIVIDUALIZED PRICE INDEX;NUTRITIONAL TAX SYSTEM;FOOD TAX
Voltage induced control and magnetoresistance of noncollinear frustrated magnets
Noncollinear frustrated magnets are proposed as a new class of spintronic
materials with high magnetoresistance which can be controlled with relatively
small applied voltages. It is demonstrated that their magnetic configuration
strongly depends on position of the Fermi energy and applied voltage. The
voltage induced control of noncollinear frustrated materials (VCFM) can be seen
as a way to intrinsic control of colossal magnetoresistance (CMR) and is the
bulk material counterpart of spin transfer torque concept used to control giant
magnetoresistance in layered spin-valve structures.Comment: 4 pages, 4 figure
Nucleon exchange in heavy-ion collisions within stochastic mean-field approach
Nucleon exchange mechanism is investigated in deep-inelastic symmetric
heavy-ion collisions in the basis of the Stochastic Mean-Field approach. By
extending the previous work to off-central collisions, analytical expression is
deduced for diffusion coefficient of nucleon exchange mechanism. Numerical
calculations are carried out for Ca + Ca and Zr +
Zr systems and the results are compared with the phenomenological
nucleon exchange model. Also, calculations are compared with the available
experimental results of deep-inelastic collisions between calcium nuclei.Comment: 8 pages, 7 figure
An evaluation of Northern Florida Bay as a nursery area for red drum, Sciaenops ocellatus, and other juvenile and small resident fishes.
Red drum is one ofthe most popular species sought by anglers in Florida Bay, yet juveniles are rarely encountered. We evaluated Florida Bay as a nursery area for red drum by sampling for recently-settled late larvae in basin areas within the bay with an epi-benthic sled at
six stations in November 2000, and at seven stations during December 2000 through February 2001. In November 2000 we surveyed potential sampling sites in quiet backwaters adjacent to mangroves for juvenile red drum. A total of 202 sites were sampled mainly in northern Florida Bay and adjacent waters with a cast net. We collected only one recently-settled red drum larvae and no juveniles. Obviously the sites that we sampled in Florida Bay and adjacent waters are not nursery habitat for this valuable species. Sled collections were dominated by bay anchovy,
Anchoa mitchilli, but densities were biased by one collection. Five small resident species were among the dominant species: rainwater killifish, Lucania parva; dusky pipefish, Syngnathus floridae; dwarf seahorse, Hippocampus zosterae; and clown goby, Microgobius gulosus. Three
species that spawn outside Florida Bay in the GulfofMexico were common: pinfish, Lagodon rhomboides; pigfish, Orthopristis chrysoptera; and silver perch, Bairdiella chrysoura. Twenty-seven species were collected with the cast net. Hardhead silversides (Atherinomorus stipes), bay
anchovy, tidewater mojarra (Eucinostomus harengulus), silver jenny (Eucinostomus gula), and goldspotted killifish (Floridichthys carpio) were the most common in cast net collections. Although only one red drum was collected, we were able to: (1) identify mesohaline waters from our cast net sites to test our preliminary assessment that mesohaline habitat might be limited in Florida Bay, (2) document the distribution and abundance of fishes collected by cast net that should enhance our understanding of ichthyofauna in the Northern Subdivision ofFlorida Bay
and adjacent waters, and (3) from epibenthic sled collections, describe the habitats, abundance and distribution of recently settled larvae/small juveniles/small resident fishes during late fall and winter. This information should be useful to managers and future research. (PDF contains 34 pages
Graphene in periodically alternating magnetic field: unusual quantization of the anomalous Hall effect
We study the energy spectrum and electronic properties of graphene in a
periodic magnetic field of zero average with a symmetry of triangular lattice.
The periodic field leads to formation of a set of minibands separated by gaps,
which can be manipulated by external field. The Berry phase, related to the
motion of electrons in space, and the corresponding Chern numbers
characterizing topology of the energy bands are calculated analytically and
numerically. In this connection, we discuss the anomalous Hall effect in the
insulating state, when the Fermi level is located in the minigap. The results
of calculations show that in the model of gapless Dirac spectrum of graphene
the anomalous Hall effect can be treated as a sum of fractional quantum
numbers, related to the nonequivalent Dirac points.Comment: 6 pages, 5 figure
Life History, Diet, Abundance and Distribution, and Length-Frequencies of Selected Invertebrates in Florida Bay, Everglades National Park, Florida
This report presents information on the life history, diet, abundance and distribution, and length-frequency distributions of five invertebrates in Florida Bay, Everglades National Park. Collections were made with an otter trawl in basins on a bi-monthly basis. Non-parametric
statistics were used to test spatial and temporal differences in the abundance of invertebrates when numbers were appropriate (i. e., $25). Invertebrate species are presented in four sections. The sections on Life History, and Diet were derived from the literature. The section on
Abundance and Distribution consists of data from otter-trawl collections. In addition, comparisons with other studies are included here following our results. The section on Length-frequency Distributions consists of length measurements from all collections, except 1984-1985
when no measurements were taken. Length-frequency distributions were used, when possible, to estimate life stage captured, spawning times, recruitment into Florida Bay for those species which spawn outside the Bay, and growth. Additional material from the literature was added
when appropriate. (PDF contains 39 pages
Dzyaloshinski-Moriya interactions in the kagome lattice
The kagom\'e lattice exhibits peculiar magnetic properties due to its
strongly frustated cristallographic structure, based on corner sharing
triangles. For nearest neighbour antiferromagnetic Heisenberg interactions
there is no Neel ordering at zero temperature both for quantum and classical s
pins. We show that, due to the peculiar structure, antisymmetric
Dzyaloshinsky-Moriya interactions ()
are present in this latt ice. In order to derive microscopically this
interaction we consider a set of localized d-electronic states. For classical
spins systems, we then study the phase diagram (T, D/J) through mean field
approximation and Monte-Carlo simulations and show that the antisymmetric
interaction drives this system to ordered states as soon as this interaction is
non zero. This mechanism could be involved to explain the magnetic structure of
Fe-jarosites.Comment: 4 pages, 2 figures. Presented at SCES 200
Anomalous Hall Effect due to the spin chirality in the Kagom\'{e} lattice
We consider a model for a two dimensional electron gas moving on a kagom\'{e}
lattice and locally coupled to a chiral magnetic texture. We show that the
transverse conductivity does not vanish even if spin-orbit
coupling is not present and it may exhibit unusual behavior. Model parameters
are the chirality, the number of conduction electrons and the amplitude of the
local coupling. Upon varying these parameters, a topological transition
characterized by change of the band Chern numbers occur. As a consequence,
can be quantized, proportional to the chirality or have a non
monotonic behavior upon varying these parameters.Comment: 8 pages, 7 figure
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