565 research outputs found
Survey of the Farm Management, Focusing on the Regional Difference and Cattle Farming in Burkina Faso
In Burkina Faso the history using of cattle as draft power for cultivation is not long. This study was conducted to investigate the farm management, focusing on the regional difference and the presence of cattle farming in the country. Interview was carried out on 30 farms from B Province in the Centre-West Region consisting of 8 non-cattle owners (BNs) and 22 cattle owners (BCs), and on 9 farms of cattle owners from H Province in the Haut-Bassins Region (HCs) in November 2013. The average household sizes of BNs, BCs and HCs were 16.5, 27.2 and 31.3, respectively. The ratios of BNs, BCs and HCs having income sources from livestock farming equivalent to or more than crop farming were 25, 50 and 67%, respectively. The average cattle number of BCs was 8.6 and that of HCs was 50.8. The average planted areas of BNs, BCs and HCs were 4.9, 12.0 and 7.0 ha, respectively. The BCs and BNs had large planted area of millet, rice, sorghum and peanut, on the other hand, planted area of maize, sesame seed, cotton and vegetables was large in HCs. The gross income from the crop farming of BNs and BCs were 95,000 and 114,000 FCFA/year, respectively, which were higher than that of HCs: 59,000 FCFA/year. The gross income and profit from cattle farming of HCs were twice and thrice as high as those of BCs, respectively. The ratio of the gross income from cattle farming to that from total farming of BCs and HCs were high, 72 and 80%, respectively. The results suggested that cattle farming contributed to the profit of farmers in B Province, who had a low profit margin of the crop and vegetable farming due to the constraints of soil condition and climate results from the limit of precipitation
Delay Induced Excitability
We analyse the stochastic dynamics of a bistable system under the influence
of time-delayed feedback. Assuming an asymmetric potential, we show the
existence of a regime in which the systems dynamic displays excitability by
calculating the relevant residence time distributions and correlation times.
Experimentally we then observe this behaviour in the polarization dynamics of a
vertical cavity surface emitting laser with opto-electronic feedback. Extending
these observations to two-dimensional systems with dispersive coupling we
finally show numerically that delay induced excitability can lead to the
appearance of propagating wave-fronts and spirals.Comment: 5 pages, 6 figure
A propensity criterion for networking in an array of coupled chaotic systems
We examine the mutual synchronization of a one dimensional chain of chaotic
identical objects in the presence of a stimulus applied to the first site. We
first describe the characteristics of the local elements, and then the process
whereby a global nontrivial behaviour emerges. A propensity criterion for
networking is introduced, consisting in the coexistence within the attractor of
a localized chaotic region, which displays high sensitivity to external
stimuli,and an island of stability, which provides a reliable coupling signal
to the neighbors in the chain. Based on this criterion we compare homoclinic
chaos, recently explored in lasers and conjectured to be typical of a single
neuron, with Lorenz chaos.Comment: 4 pages, 3 figure
Construction of an isotropic cellular automaton for a reaction-diffusion equation by means of a random walk
We propose a new method to construct an isotropic cellular automaton
corresponding to a reaction-diffusion equation. The method consists of
replacing the diffusion term and the reaction term of the reaction-diffusion
equation with a random walk of microscopic particles and a discrete vector
field which defines the time evolution of the particles. The cellular automaton
thus obtained can retain isotropy and therefore reproduces the patterns found
in the numerical solutions of the reaction-diffusion equation. As a specific
example, we apply the method to the Belousov-Zhabotinsky reaction in excitable
media
Mismatch between morphological and functional assessment of the length of coronary artery disease
Background: Morphological evaluation of coronary lesion length is a paramount step during invasive assessment of coronary artery disease. Likewise, the extent of epicardial pressure losses can be measured using longitudinal vessel interrogation with fractional flow reserve (FFR) pullbacks. We aimed to quantify the mismatch in lesion length between morphological (based on quantitative coronary angiography, QCA, and optical coherence tomography, OCT) and functional evaluations. Methods: This is a prospective and multicenter study of patients evaluated by QCA, OCT and motorized fractional flow reserve pullbacks (mFFR). The difference in lesion length between the functional and anatomical evaluations was referred to as FAM. Results: 117 patients (131 vessels) were included. Median lesion length derived from angiography was 16.05 mm [11.40–22.05], from OCT was 28.00 mm [16.63–38.00] and from mFFR 67.12 mm [25.38–91.37]. There was no correlation between QCA and mFFR lesion length (r = 0.124, 95% CI -0.168-0.396, p = 0.390). OCT lesion length did correlate with mFFR (r = 0.469, 95% CI 0.156–0.696, p = 0.004). FAM was strongly associated with the improvement in vessel conductance with percutaneous coronary intervention (PCI), higher mismatch was associated with lower post-PCI FFR. Conclusions: Lesion length assessment differs between morphological and functional evaluations. The morphological-functional mismatch in lesion length is frequent, and influences the results of PCI in terms of post-PCI FFR. Integration of the extent of pressure losses provides clinically relevant information that may be useful for clinical decision-making concerning revascularization strategy
Synchronisation in Coupled Sine Circle Maps
We study the spatially synchronized and temporally periodic solutions of a
1-d lattice of coupled sine circle maps. We carry out an analytic stability
analysis of this spatially synchronized and temporally periodic case and obtain
the stability matrix in a neat block diagonal form. We find spatially
synchronized behaviour over a substantial range of parameter space. We have
also extended the analysis to higher spatial periods with similar results.
Numerical simulations for various temporal periods of the synchronized
solution, reveal that the entire structure of the Arnold tongues and the
devil's staircase seen in the case of the single circle map can also be
observed for the synchronized coupled sine circle map lattice. Our formalism
should be useful in the study of spatially periodic behaviour in other coupled
map lattices.Comment: uuencoded, 1 rextex file 14 pages, 3 postscript figure
Observational operators for dual polarimetric radars in variational data assimilation systems (PolRad VAR v1.0)
We implemented two observational
operators for dual polarimetric radars in two variational data assimilation
systems: WRF Var, the Weather Research and Forecasting Model variational data
assimilation system, and NHM-4DVAR, the nonhydrostatic variational data
assimilation system for the Japan Meteorological Agency nonhydrostatic model.
The operators consist of a space interpolator, two types of variable
converters, and their linearized and transposed (adjoint) operators. The
space interpolator takes account of the effects of radar-beam broadening in
both the vertical and horizontal directions and climatological beam bending.
The first variable converter emulates polarimetric parameters with model
prognostic variables and includes attenuation effects, and the second one
derives rainwater content from the observed polarimetric parameter (specific
differential phase). We developed linearized and adjoint operators for the
space interpolator and variable converters and then assessed whether the
linearity of the linearized operators and the accuracy of the adjoint
operators were good enough for implementation in variational systems. The
results of a simple assimilation experiment showed good agreement between
assimilation results and observations with respect to reflectivity and
specific differential phase but not with respect to differential
reflectivity
Heterogeneous Delays in Neural Networks
We investigate heterogeneous coupling delays in complex networks of excitable
elements described by the FitzHugh-Nagumo model. The effects of discrete as
well as of uni- and bimodal continuous distributions are studied with a focus
on different topologies, i.e., regular, small-world, and random networks. In
the case of two discrete delay times resonance effects play a major role:
Depending on the ratio of the delay times, various characteristic spiking
scenarios, such as coherent or asynchronous spiking, arise. For continuous
delay distributions different dynamical patterns emerge depending on the width
of the distribution. For small distribution widths, we find highly synchronized
spiking, while for intermediate widths only spiking with low degree of
synchrony persists, which is associated with traveling disruptions, partial
amplitude death, or subnetwork synchronization, depending sensitively on the
network topology. If the inhomogeneity of the coupling delays becomes too
large, global amplitude death is induced
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