19,178 research outputs found
Female consumption and evaluation of traditionally male orientated products : a self monitoring perspective
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
The Effects of Government Maize Marketing Policies on Maize Market Prices in Kenya
The Government of Kenya pursues maize marketing policy objectives through the National Cereals and Produce Board (NCPB) which procures and sells maize at administratively determined prices, and stores maize as a contingency against future shortages. A private sector marketing channel competes with the NCPB and prices in this channel are set by supply and demand forces. This paper estimates the effects of NCPB activities on the historical path of private sector maize market prices in Kenya between 1989 and 2004. Results provide important insights into the historical effects of the NCPB, and will provide useful input into deliberations on the appropriate role for the NCPB in the future. It was not possible to use a fully structural econometric model to estimate the historical policy effects because of data limitations in Kenya, which are typical of many developing countries. Instead we use a reduced form vector autoregression model (VAR) and show how policy simulation results can be obtained from a fairly parsimonious VAR that can be estimated with sparse data and imposes only minimal identification restrictions. Results show that NCPB activities have stabilized maize market prices in Kenya, reduced price levels in the early 1990s, and raised price levels by roughly 20 percent between 1995 and 2004. Because roughly 60 percent of Kenya's rural households purchase maize while less than 30 percent sell maize, the government's maize marketing board operations have transferred income from urban consumers and most small rural households to maize selling farmers.Kenya, income transfers, maize policy, price stabilization, VAR, International Development, C22, O2, Q13, Q18,
Toward a Minimum Branching Fraction for Dark Matter Annihilation into Electromagnetic Final States
Observational limits on the high-energy neutrino background have been used to
place general constraints on dark matter that annihilates only into standard
model particles. Dark matter particles that annihilate into neutrinos will also
inevitably branch into electromagnetic final states through higher-order tree
and loop diagrams that give rise to charged leptons, and these charged
particles can transfer their energy into photons via synchrotron radiation or
inverse Compton scattering. In the context of effective field theory, we
calculate the loop-induced branching ratio to charged leptons and show that it
is generally quite large, typically >1%, when the scale of the dark matter mass
exceeds the electroweak scale, M_W. For a branching fraction >3%, the
synchrotron radiation bounds on dark matter annihilation are currently stronger
than the corresponding neutrino bounds in the interesting mass range from 100
GeV to 1 TeV. For dark matter masses below M_W, our work provides a plausible
framework for the construction of a model for "neutrinos only" dark matter
annihilations.Comment: 18 pages, 4 figures, discussion added, matches version in Phys. Rev.
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