1,785 research outputs found
Alien Registration- Brewer, Ella M. (Wade, Aroostook County)
https://digitalmaine.com/alien_docs/32592/thumbnail.jp
Influence of guanxi, trust and farmer-specific factors on participation in emerging vegetable markets in China
The fast development of market outlets (e.g., supermarkets, processing industries, international markets) in China provides rich opportunities for small-scale farmers to upgrade quality and increase income. However, the high level of transaction costs incurred in small-volume-based vegetable transactions hinders farmers from participating in these emerging markets. This article explores how personal relationships (called guanxi in China) and trust between farmers and their buyers influence transaction costs in vegetable transactions, and thereby also farmers’ participation in emerging markets. We interviewed 167 vegetable farmers in Jiangsu Province, which provided data for empirical testing using two-stage probit analysis with endogenous variables. The findings suggest that guanxi and trust effectively reduce transaction costs in vegetable marketing in China, which may help and encourage farmers to better participate in emerging markets. The results also reveal that farmers’ age, education, marketing experience, distance to the market, production scale and land quality influence transaction costs. The article ends with policy implications with respect to efficiently reducing transaction costs in vegetable supply chains in order to create a better environment for small-scale farmers in emerging markets in China
MHV Lagrangian for N=4 Super Yang-Mills
Here we formulate two field redefinitions for N=4 Super Yang-Mills in light
cone superspace that generates only MHV vertices in the new Lagrangian. After
careful consideration of the S-matrix equivalence theorem, we see that only the
canonical transformation gives the MHV Lagrangian that would correspond to the
CSW expansion. Being in superspace, it is easier to analyse the equivalence
theorem at loop level. We calculate the on shell amplitude for 4pt
MHV in the new lagrangian and
show that it reproduces the previously known form. We also briefly discuss the
relationship with the off-shell continuation prescription of CSW.Comment: 17 pages 4 figures, 2 sections and several references added typo
correcte
Segmentation of Loops from Coronal EUV Images
We present a procedure which extracts bright loop features from solar EUV
images. In terms of image intensities, these features are elongated ridge-like
intensity maxima. To discriminate the maxima, we need information about the
spatial derivatives of the image intensity. Commonly, the derivative estimates
are strongly affected by image noise. We therefore use a regularized estimation
of the derivative which is then used to interpolate a discrete vector field of
ridge points ``ridgels'' which are positioned on the ridge center and have the
intrinsic orientation of the local ridge direction. A scheme is proposed to
connect ridgels to smooth, spline-represented curves which fit the observed
loops. Finally, a half-automated user interface allows one to merge or split,
eliminate or select loop fits obtained form the above procedure. In this paper
we apply our tool to one of the first EUV images observed by the SECCHI
instrument onboard the recently launched STEREO spacecraft. We compare the
extracted loops with projected field lines computed from
almost-simultaneously-taken magnetograms measured by the SOHO/MDI Doppler
imager. The field lines were calculated using a linear force-free field model.
This comparison allows one to verify faint and spurious loop connections
produced by our segmentation tool and it also helps to prove the quality of the
magnetic-field model where well-identified loop structures comply with
field-line projections. We also discuss further potential applications of our
tool such as loop oscillations and stereoscopy.Comment: 13 pages, 9 figures, Solar Physics, online firs
Poisson homology of r-matrix type orbits I: example of computation
In this paper we consider the Poisson algebraic structure associated with a
classical -matrix, i.e. with a solution of the modified classical
Yang--Baxter equation. In Section 1 we recall the concept and basic facts of
the -matrix type Poisson orbits. Then we describe the -matrix Poisson
pencil (i.e the pair of compatible Poisson structures) of rank 1 or -type
orbits of . Here we calculate symplectic leaves and the integrable
foliation associated with the pencil. We also describe the algebra of functions
on -type orbits. In Section 2 we calculate the Poisson homology of
Drinfeld--Sklyanin Poisson brackets which belong to the -matrix Poisson
family
Proof of the MHV vertex expansion for all tree amplitudes in N=4 SYM theory
We prove the MHV vertex expansion for all tree amplitudes of N=4 SYM theory.
The proof uses a shift acting on all external momenta, and we show that every
N^kMHV tree amplitude falls off as 1/z^k, or faster, for large z under this
shift. The MHV vertex expansion allows us to derive compact and efficient
generating functions for all N^kMHV tree amplitudes of the theory. We also
derive an improved form of the anti-NMHV generating function. The proof leads
to a curious set of sum rules for the diagrams of the MHV vertex expansion.Comment: 40 pages, 7 figure
Determination of color-octet matrix elements from e^+e- process at low energies
We present an analysis of the preliminary experimental data of direct j/psi
production in e^e- process at low energies. We find that the color-octet
contributions are crucially important to the cross section at this energy
region, and their inclusion produces a good description of the data. By fitting
to the data, we extract the individual values of two color-octet matrix
elements: \approx 1.1\times 10^{-2} GeV^3, <{\cal
O}_8^{\psi}(^3P_0)> m_c^2\approx 7.4\times 10^{-3}GeV^3. We discuss the allowed
range of the two matrix elements constrained by the theoretical uncertainties.
We find that is poorly determined because it is
sensitive to the variation of the choice of m_c, \alpha_s and <{\cal
O}_1^{\psi}(^3S_1)>. However m_c^2 is quite stable
(about (6-9)\times 10^{-3}GeV^3) when the parameters vary in reasonable ranges.
The uncertainties due to large experimental errors are also discussed.Comment: 13 page, RevTex, 2 figures in postscript. To appear in Phys. Rev.
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