18,294 research outputs found
From Differentiated Coffee Markets Towards Alternative Trade and Knowledge Networks
This chapter presents a case study focusing on the Community Agroecology Network (CAN), an organization started by the United States and Mesoamerica’s activists, whose effort is to create an alternative trade and knowledge network. The basic aim behind CAN is to benefit conservation and social development efforts by linking producers, consumers, and producer organizations. CAN is a response to the problems arising out of the dominance of certification processes in Fair Trade and organic coffee networks, and the chapter discusses the organization’s main goals of intercommunity relationship development, direct coffee marketing, and ecological sustainability. It moots a comparison between alternative agro-food networks and CAN on the grounds of biodiversity conservation, empowerment, and enhanced livelihoods
Hadronic molecules: meson-baryon hybrids
The existence of hadronic molecular-type hybrids consisting of a baryon and a
meson is argued. Long-range interactions due to one-pion exchange is shown to
be strong enough to produce a loosely bound state. Specific features of a
molecular hybrid are discussed.Comment: 7 pages in RevTeX plus 1 figure (available upon request
The effect of reionization on the COBE normalization
We point out that the effect of reionization on the microwave anisotropy
power spectrum is not necessarily negligible on the scales probed by COBE. It
can lead to an upward shift of the COBE normalization by more than the
one-sigma error quoted ignoring reionization. We provide a fitting function to
incorporate reionization into the normalization of the matter power spectrum.Comment: 3 pages LaTeX file with three figures incorporated (uses mn.sty and
epsf
Self-dual solutions of Yang-Mills theory on Euclidean AdS space
We find non-trivial, time-dependent solutions of the (anti) self-dual
Yang-Mills equations in the four dimensional Euclidean Anti-de Sitter space. In
contrast to the Euclidean flat space, the action depends on the moduli
parameters and the charge can take any non-integer value.Comment: 11 pages, 2 figures; version 2: new references added, to appear in
PR
Low frequency measurements of synchrotron absorbing HII regions and modeling of observed synchrotron emissivity
Cosmic rays (CRs) and magnetic fields are dynamically important components in
the Galaxy, and their energy densities are comparable to that of the turbulent
interstellar gas. The interaction of CRs and Galactic magnetic fields produces
synchrotron radiation clearly visible in the radio regime. Detailed
measurements of synchrotron radiation averaged over the line-of-sight (LOS),
so-called synchrotron emissivities, can be used as a tracer of the CR density
and Galactic magnetic field (GMF) strength. Our aim is to model the synchrotron
emissivity in the Milky Way using a 3 dimensional dataset instead of
LOS-integrated intensity maps on the sky. Using absorbed HII regions we can
measure the synchrotron emissivity over a part of the LOS through the Galaxy,
changing from a 2 dimensional to a 3 dimensional view. Performing these
measurements on a large scale is one of the new applications of the window
opened by current low frequency arrays. Using various simple axisymmetric
emissivity models and a number of GMF-based emissivity models we can simulate
the synchrotron emissivities and compare them to the observed values in the
catalog. We present a catalog of low-frequency absorption measurements of HII
regions, their distances and electron temperatures, compiled from literature.
These data show that the axisymmetric emissivity models are not complex enough,
but the GMF-based emissivity models deliver a reasonable fit. These models
suggest that the fit can be improved by either an enhanced synchrotron
emissivity in the outer reaches of the Milky Way, or an emissivity drop near
the Galactic center. State-of-the-art GMF models plus a constant CR density
model cannot explain low-frequency absorption measurements, but the fits
improved with slight (ad-hoc) adaptations. It is clear that more detailed
models are needed, but the current results are very promising.Comment: 14 pages, 9 figures, accepted for publication in A&
The Drell-Yan process and Deep Inelastic Scattering from the lattice
We report on measurements of the h_1 structure function, relevant to
calculating cross-sections for the Drell-Yan process. This is a quantity which
can not be measured in Deep Inelastic Scattering, it gives additional
information on the spin carried by the valence quarks, as well as insights on
how relativistic the quarks are.Comment: 3 pages, Latex, 3 figures, espcrc2.sty included, Talk presented at
LATTICE96(phenomenology
The nonperturbative origin of delta-function singularity in the chirally-odd twist-3 distribution function e(x)
We analytically prove that the existence of the delta-function singularity in
the chirally-odd twist-3 distribution of the nucleon is inseparably
connected with the nonvanishing quark condensate as a signal of the spontaneous
chiral symmetry breaking of the QCD vacuum. This singularity in , which
would be observed as a sizable violation of the 1st moment sum rule, is then
interpreted as giving a very rare case that the nontrivial vacuum structure of
QCD manifests in an observable of a localized QCD excitation, i.e. the nucleon.Comment: 9 pages, 1 eps-figur
Ex-ante measure of patent quality reveals intrinsic fitness for citation-network growth
We have constructed a fitness parameter, characterizing the intrinsic
attractiveness for patents to be cited, from attributes of the associated
inventions known at the time a patent is granted. This exogenously obtained
fitness is shown to determine the temporal growth of the citation network in
conjunction with mechanisms of preferential attachment and obsolescence-induced
ageing that operate without reference to characteristics of individual patents.
Our study opens a window on understanding quantitatively the interplay of the
rich-gets-richer and fit-gets-richer paradigms that have been suggested to
govern the growth dynamics of real-world complex networks.Comment: 6 pages, 3 figures, RevTex4.1, v2: minor changes, version to appear
as a Rapid Communication in Phys. Rev.
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