Futures for farmers: hedging participation and the Mexican corn scheme

Administered commodity price schemes in developing countries have proved ineffective in raising farmers' incomes and price stabilisation through futures markets is increasingly advocated as the alternative policy objective. A potential difficulty is that farmers tend not to hedge extensively, even in developed countries where access to futures markets is long established. Explanations for this reticence are examined here with context provided by the Mexican hedging programme, which incorporates financial incentives to spur adoption. Applying representative data for corn to a well-known analysis of the hedging decision suggests that limited participation may reflect rational calculation rather than farmer 'inertia'. A policy implication is that permanent access subsidies are difficult to justify from the national perspective.

Genetic parameters of wool colour and skin traits in Corriedale sheep.

Clean wool colour (CWC) is an important wool price determinant and has been related to suint characteristics, i.e. sudoriparous and sebaceous gland secretions, such as suint percentage and suint K content. In this work heritability, phenotypic and genetic correlations among wool colour and skin traits were examined. The genetic estimates were assessed by Restricted Maximum Likelihood (REML) procedures using average information algorithm (AIREML) in a Corriedale flock. The traits analysed were wool colour traits (CWC), yellow predictive colour (YPC), and Visual Score; suint traits such as suint percentage and potassium and sodium concentrations in suint, and physiological traits such as potassium and sodium concentrations in the skin, including plasma and red blood cells. The objectives of this study were to assess phenotypic and genetic correlations between wool colour and skin traits, and to find the suitability of these traits as indirect selection criteria for clean wool colour. Suint traits were highly genetically correlated to YPC. Suint K, but not suint percentage, was found to have a high genetic correlation with CWC. Skin K, Visual Score, YPC and suint K were amongst the best indirect selection criteria for clean wool colour. However, selection using these traits was expected to reduceCWCfrom 52% to 49% of that estimated under direct selection

Melhoramento de espécies aquícolas com foco na resistência a doenças.

Introdução. Aspectos a serem considerados no melhoramento genético com foco em doenças. Estimativas de herdabilidade e de correlações genéticas entre resistência a doenças e outras características. Cuidados no desenho experimental dos desafios para a fenotipagem de animais. Considerações finais. Referências.bitstream/item/136151/1/CNPASA2015doc17.pd

Indirect selection criteria against clean wool colour in Corriedale sheep and their effects on wool production traits.

The potential of greasy wool colour subjective assessment Visual Colour Score (VCS) and the yellow predictive test (YPC) as indirect selection criteria for reduction of clean wool colour (CWC) in Corriedale sheep was examined. The heritability of these wool colour traits and the wool production traits, greasy (GFW) and clean fleece weights (CFW), and mean fibre diameter (MFD) and the phenotypic and genetic correlations among these traits were estimated from a Corriedale flock using AIREML procedures. A high genetic correlation between YPC and CWC was observed, indicating that YPC could be a suitable indirect selection criterium for CWC. However, direct selection against CWC was predicted to produce faster genetic improvements in CWC than that expected under indirect selection via YPC. Single trait selection based on VCS or YPC were expected to reduce the response in CWC to 51% and 49% of that estimated for direct selection. The positive genetic correlations of CWC, YPC and VCS with CFW and MFD would cause a reduction in both MFD and CFW to result from selection that reduces wool colour. The results showed that the most effective way to genetically improve CWC was through indirect selection to reduce MFD, CFW or GFW, followed by direct selection, but the premiums for CWC in the Corriedale breed may not be sufficient to justify the expected losses in CFW

How to Complete an Interactive Configuration Process?

When configuring customizable software, it is useful to provide interactive tool-support that ensures that the configuration does not breach given constraints. But, when is a configuration complete and how can the tool help the user to complete it? We formalize this problem and relate it to concepts from non-monotonic reasoning well researched in Artificial Intelligence. The results are interesting for both practitioners and theoreticians. Practitioners will find a technique facilitating an interactive configuration process and experiments supporting feasibility of the approach. Theoreticians will find links between well-known formal concepts and a concrete practical application.Comment: to appear in SOFSEM 201

A putative resistant DNA marker for wool yellowing susceptibility in sheep.

An Australian Merino flock was screened for low (resistant) and high (susceptible) yellow predictive colour (YPC) breeding values in order to compare extreme individuals using the differential display of mRNA technique. One differentially expressed cDNA band was visualised only in the resistant group. This band showed no identity with the DNA sequences of public databases; however, they showed short homologies with three database sequences related to transmembrane signalling functions. The use of these candidate genes as DNA markers needs to be confirmed against sheep with a wide range of susceptibility to wool yellowing to verify the results

Variability Modelling Challenges from the Trenches of an Open Source Product Line Re-Engineering Project

Variability models, feature diagrams ahead, have become commonplace in the software product lines engineering literature. Whereas ongoing research keeps improving their expressiveness, formalisation and automation, more experience reports on their usage in real projects are needed. This paper describes some challenges encountered during the re-engineering of PloneMeeting, an Open Source software family, into a software product line. The main challenging issues we could observe were (i) the ambiguity originating from implicit information (missing definitions of feature labels and unclear modelling viewpoint), (ii) the necessity of representing spurious features, (iii) the difficulty of making diagrams and constraints resistant to change, and (iv) the risks of using feature attributes to represent large sets of subfeatures. Our study reveals the limitations of current constructs, and calls for both language and methodological improvements. It also suggests further comparative evaluations of modelling alternatives.Comisión Interministerial de Ciencia y Tecnología TIN2006-0047

Physical Wigner functions

In spite of their potential usefulness, the characterizations of Wigner functions for Bose and Fermi statistics given by O'Connell and Wigner himself almost thirty years ago has drawn little attention. With an eye towards applications in quantum chemistry, we revisit and reformulate them in a more convenient way.Comment: Latex, 10 page