Storage of organically produced crops (OF0127T)

This is the final report of Defra Project OF0127T. The main objective of this review was to establish best storage practice for field vegetables, potatoes, cereals and top fruit. A literature review was carried out and information was also gathered from the industry. Information relevant to growers and farmers has been drawn together to provide a comprehensive base from which technical advisory leaflets can be produced. The costs of different storage methods are provided, and case studies used wherever possible. In general, organic crops can be stored using the same methods as conventional crops but there is an increased risk that sometimes there will be higher storage losses because pesticides and sprout suppressants are not used. On the whole, specific problems with pests and diseases can be avoided using good organic husbandry techniques and by storing undamaged, healthy crops. In the case of cereals storage at correct moisture content and temperatures can avoid pests and moulds. However, there are some areas where more technical development or research would be useful and these have been identified. Relatively few organic growers store vegetables, but in order to maintain a supply of good quality UK produce throughout the year, more long term cold storage space is required (either on farm or in co-operative type stores). Based on the limited data available, economic analysis revealed that long term storage of organic vegetables has generally not been profitable. However, as the market expands in the future, it is likely that storage will become as essential for vegetables as it is for organic cereals and fruit

Phase-space structure of two-dimensional excitable localized structures

In this work we characterize in detail the bifurcation leading to an excitable regime mediated by localized structures in a dissipative nonlinear Kerr cavity with a homogeneous pump. Here we show how the route can be understood through a planar dynamical system in which a limit cycle becomes the homoclinic orbit of a saddle point (saddle-loop bifurcation). The whole picture is unveiled, and the mechanism by which this reduction occurs from the full infinite-dimensional dynamical system is studied. Finally, it is shown that the bifurcation leads to an excitability regime, under the application of suitable perturbations. Excitability is an emergent property for this system, as it emerges from the spatial dependence since the system does not exhibit any excitable behavior locally.Comment: 10 pages, 9 figure

Fluctuations and correlations in hexagonal optical patterns

We analyze the influence of noise in transverse hexagonal patterns in nonlinear Kerr cavities. The near field fluctuations are determined by the neutrally stable Goldstone modes associated to translational invariance and by the weakly damped soft modes. However these modes do not contribute to the far field intensity fluctuations which are dominated by damped perturbations with the same wave vectors than the pattern. We find strong correlations between the intensity fluctuations of any arbitrary pair of wave vectors of the pattern. Correlation between pairs forming 120 degrees is larger than between pairs forming 180 degrees, contrary to what a naive interpretation of emission in terms of twin photons would suggest.Comment: 10 pages, 13 figure

Friend or foe? The role of state and mutual Fund ownership in the split share structure reform in China

The recent split share structure reform in China involves the nontradable shareholders proposing a compensation package to the tradable shareholders in exchange for the listing rights of their shares. We find that state ownership (the major owners of nontradable shares) has a positive effect on the final compensation ratio. In contrast, mutual fund ownership (the major institutional owner of tradable shares) has a negative effect on the compensation ratio and especially in state-owned firms. The evidence is consistent with our predictions that state shareholders have incentives to complete the reform quickly and exert political pressure on mutual funds to accept the terms without a fight. Copyright © 2010 Michael G. Foster School of Business, University of Washington.published_or_final_versio

Drifting instabilities of cavity solitons in vertical cavity surface-emitting lasers with frequency selective feedback

In this paper we study the formation and dynamics of self-propelled cavity solitons (CSs) in a model for vertical cavity surface-emitting lasers (VCSELs) subjected to external frequency selective feedback (FSF), and build their bifurcation diagram for the case where carrier dynamics is eliminated. For low pump currents, we find that they emerge from the modulational instability point of the trivial solution, where traveling waves with a critical wavenumber are formed. For large currents, the branch of self-propelled solitons merges with the branch of resting solitons via a pitchfork bifurcation. We also show that a feedback phase variation of 2\pi can transform a CS (whether resting or moving) into a different one associated to an adjacent longitudinal external cavity mode. Finally, we investigate the influence of the carrier dynamics, relevant for VCSELs. We find and analyze qualitative changes in the stability properties of resting CSs when increasing the carrier relaxation time. In addition to a drifting instability of resting CSs, a new kind of instability appears for certain ranges of carrier lifetime, leading to a swinging motion of the CS center position. Furthermore, for carrier relaxation times typical of VCSELs the system can display multistability of CSs.Comment: 11 pages, 12 figure

Leverage and investment under a state-owned bank lending environment: Evidence from China

This study examines the relations between leverage and investment in China's listed firms, where corporate debt is principally provided by state-owned banks. We obtain three major findings. First, there is a negative relation between leverage and investment. Second, the negative relation between leverage and investment is weaker in firms with low growth opportunities and poor operating performance than in firms with high growth opportunities and good operating performance. Third, the negative relation between leverage and investment is weaker in firms with a higher level of state shareholding than in firms with a lower level of state shareholding. Overall, our results are consistent with the hypothesis that the state-owned banks in China impose fewer restrictions on the capital expenditures of low growth and poorly performing firms and also firms with greater state ownership. This creates an overinvestment bias in these firms.preprin

Spatial correlations in hexagons generated via a Kerr nonlinearity

We consider the hexagonal pattern forming in the cross-section of an optical beam produced by a Kerr cavity, and we study the quantum correlations characterizing this structure. By using arguments related to the symmetry broken by the pattern formation, we identify a complete scenario of six-mode entanglement. Five independent phase quadratures combinations, connecting the hexagonal modes, are shown to exhibit sub-shot-noise fluctuations. By means of a non-linear quantum calculation technique, quantum correlations among the mode photon numbers are demonstrated and calculated.Comment: ReVTeX file, 20 pages, 7 eps figure