7,356 research outputs found
World Soybean Demand: An Elasticity Analysis and Long-Term Projections
Soybeans are one of the most valuable crops in the world and are characterized by their multi-purpose uses: food, feed, fuel and other industrial usages such as paint, inks, and plastics. Out of 183.9 million tons of world supply/demand of soybeans in 2001-03 year, about 10% of them were directly consumed as food (5.9%) or feed (3.8%) but 84.2% of them were crushed into soyoil and soymeal. Soyoil is mainly processed to vegetable oil for human consumption and recently used as a biodiesel feedstock. Soymeal is used not only as feed for livestock (especially for pork and poultry due to its low fiber level) and aquaculture, but also as a good source of protein for the human diet in a variety of forms in different cultures. This paper analyzes the relationship of the demand for soybeans with economy at country and international levels. We use the county level domestic demand quantities with GDP data and apply an error correction mechanism (ECM) to estimate the long-term elasticities of demand for soybeans in the market/economy. Using the estimated long-term elasticities, the demands for soybeans are projected through 2030.soybean demand, elasticity, error correction mechanism (ECM), projection, Agribusiness, Crop Production/Industries, Demand and Price Analysis, Marketing, C22, C53, Q11,
World Soybean Production: Area Harvested, Yield, and Long-Term Projections
Soybean, production, yield, land use, long-term projection, exponential smoothing with damped trend, Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Land Economics/Use, Q1,
Immunization of networks with community structure
In this study, an efficient method to immunize modular networks (i.e.,
networks with community structure) is proposed. The immunization of networks
aims at fragmenting networks into small parts with a small number of removed
nodes. Its applications include prevention of epidemic spreading, intentional
attacks on networks, and conservation of ecosystems. Although preferential
immunization of hubs is efficient, good immunization strategies for modular
networks have not been established. On the basis of an immunization strategy
based on the eigenvector centrality, we develop an analytical framework for
immunizing modular networks. To this end, we quantify the contribution of each
node to the connectivity in a coarse-grained network among modules. We verify
the effectiveness of the proposed method by applying it to model and real
networks with modular structure.Comment: 3 figures, 1 tabl
Voter model with non-Poissonian interevent intervals
Recent analysis of social communications among humans has revealed that the
interval between interactions for a pair of individuals and for an individual
often follows a long-tail distribution. We investigate the effect of such a
non-Poissonian nature of human behavior on dynamics of opinion formation. We
use a variant of the voter model and numerically compare the time to consensus
of all the voters with different distributions of interevent intervals and
different networks. Compared with the exponential distribution of interevent
intervals (i.e., the standard voter model), the power-law distribution of
interevent intervals slows down consensus on the ring. This is because of the
memory effect; in the power-law case, the expected time until the next update
event on a link is large if the link has not had an update event for a long
time. On the complete graph, the consensus time in the power-law case is close
to that in the exponential case. Regular graphs bridge these two results such
that the slowing down of the consensus in the power-law case as compared to the
exponential case is less pronounced as the degree increases.Comment: 18 pages, 8 figure
Collective fluctuations in networks of noisy components
Collective dynamics result from interactions among noisy dynamical
components. Examples include heartbeats, circadian rhythms, and various pattern
formations. Because of noise in each component, collective dynamics inevitably
involve fluctuations, which may crucially affect functioning of the system.
However, the relation between the fluctuations in isolated individual
components and those in collective dynamics is unclear. Here we study a linear
dynamical system of networked components subjected to independent Gaussian
noise and analytically show that the connectivity of networks determines the
intensity of fluctuations in the collective dynamics. Remarkably, in general
directed networks including scale-free networks, the fluctuations decrease more
slowly with the system size than the standard law stated by the central limit
theorem. They even remain finite for a large system size when global
directionality of the network exists. Moreover, such nontrivial behavior
appears even in undirected networks when nonlinear dynamical systems are
considered. We demonstrate it with a coupled oscillator system.Comment: 5 figure
Analysis of scale-free networks based on a threshold graph with intrinsic vertex weights
Many real networks are complex and have power-law vertex degree distribution,
short diameter, and high clustering. We analyze the network model based on
thresholding of the summed vertex weights, which belongs to the class of
networks proposed by Caldarelli et al. (2002). Power-law degree distributions,
particularly with the dynamically stable scaling exponent 2, realistic
clustering, and short path lengths are produced for many types of weight
distributions. Thresholding mechanisms can underlie a family of real complex
networks that is characterized by cooperativeness and the baseline scaling
exponent 2. It contrasts with the class of growth models with preferential
attachment, which is marked by competitiveness and baseline scaling exponent 3.Comment: 5 figure
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