Collective action for the conservation of on-farm genetic diversity in a center of crop diversity: an assessment of the role of traditional farmers' networks

"This project explored the possible role of collective action among small-scale farmers in managing and maintaining genetic resources in a center of crop diversity. It focused on the local institutions that ensure the supply of seed of diverse maize landraces to small-scale farmers in the Central Valleys of Oaxaca, Mexico. The key hypothesis was that the medium-to-long-term supply of a diverse set of varieties to any individual small-scale maize farmer depends on an agreement among a group of farmers to manage and supply the seed of these landraces to each other, if the need arises, and that this constitutes a form of collective action. Six communities were studied, three of them in-depth. Methodologies used included in-depth semi-structured interviews with key informants, focus group discussions, and a tracer study—following the flows of seed among different farmers. The results show that, while there is a well-developed local seed supply system based on sets of social relationships and involving multiple types of transactions, there is no evidence of collective action. Most farmers rely on and prefer to select and save seed from their own harvests. There are seed flows, however, and most seed transactions take place among people with social links, but not within a well-defined group. There are no specialized suppliers of seed, either individuals or groups. Most transactions are bilateral and while the most common transaction is the sale and purchase of seed, this is not done for profit but out of a sense of moral obligation. The system is based on the creation of trust, which is needed because seed is not transparent—that is, it is not possible to fully predict the plant phenotype that may result from a given seed simply by looking at the seed. Farmers demand different types of maize and they believe that there is a strong genotype-by-environment interaction, hence “foreign” maize types may not be appropriate for them. At the same time, farmers also find occasional experimentation beneficial and believe that they can slowly modify the characteristics of “foreign” landraces. In this system, there are strong incentives to be conservative, but also to try new landraces and experiment. The local seed system of these farmers is resilient but able to innovate as well. Interventions to support the conservation of landraces on farm, based on specialized networks for seed that rely on collective action, may not work.." Author's AbstractCentral America, Europe and North America, Small farmers, Collective action, Informal seed systems, Crop diversification, Seed supply, Trust,

Photoluminescence Studies on ZnO Thin Films Obtained by Sol-Gel Method

The sol-gel process is a friendly room temperature method to prepare transparent glasses in the form of monoliths, films, and fibers. The zinc oxide films have been obtained by sol-gel method, which are very important materials in the ceramic technology due to their piezoelectric properties and applications in various pressure transducers and acoustic-optic devices, surface and bulk acoustic wave devices, and solar cells. Structure and characteristic ultraviolet-blue emissions of amorphous and crystalline zinc oxide thin films–coated glass substrates by dip-coating deposition are explained by photoluminescence studies in this chapter

Simplified Self-Consistent Theory of Colloid Dynamics

One of the main elements of the self-consistent generalized Langevin equation (SCGLE) theory of colloid dynamics [Phys. Rev. E {\bf 62}, 3382 (2000); ibid {\bf 72}, 031107 (2005)] is the introduction of exact short-time moment conditions in its formulation. The need to previously calculate these exact short-time properties constitutes a practical barrier for its application. In this note we report that a simplified version of this theory, in which this short-time information is eliminated, leads to the same results in the intermediate and long-time regimes. Deviations are only observed at short times, and are not qualitatively or quantitatively important. This is illustrated by comparing the two versions of the theory for representative model systems.Comment: 1 text archive, 3 figure

Robust Linear Longitudinal Feedback Control of a Flapping Wing Micro Air Vehicle

This paper falls under the idea of introducing biomimetic miniature air vehicles in ambient assisted living and home health applications. The concepts of active disturbance rejection control and flatness based control are used in this paper for the trajectory tracking tasks in the flapping-wing miniature air vehicle (FWMAV) time-averaged model. The generalized proportional integral (GPI) observers are used to obtain accurate estimations of the flat output associated phase variables and of the time-varying disturbance signals. This information is used in the proposed feedback controller in (a) approximate, yet close, cancelations, as lumped unstructured time-varying terms, of the influence of the highly coupled nonlinearities and (b) the devising of proper linear output feedback control laws based on the approximate estimates of the string of phase variables associated with the flat outputs simultaneously provided by the disturbance observers. Numerical simulations are provided to illustrate the effectiveness of the proposed approach

Incorporation of biosynthesized silver nanoparticles in active biodegradable films of potato starch

En este trabajo se presenta el estudio del efecto de la incorporación de nanopartículas de plata biosintetizadas sobre las propiedades de películas biodegradables fabricadas a partir de almidón de papa y comprobar su potencial para ser usado como material activo. Las nanopartículas de plata fueron fabricadas mediante ruta verde a partir de residuos de uva y fueron añadidas en el proceso de gelatinización de las películas en concentraciones de 3% y 6% v/v. Las nanopartículas de plata fueron caracterizadas mediante espectroscopía UV-Vis y FTIR, mientras que las películas fabricas fueron caracterizadas mediante su densidad y % de contenido de humedad. Las propiedades activas se caracterizaron usando cinética de absorción de agua y biodegradación por enterramiento en suelo. Se confirmó la integración de las nanopartículas de plata en películas biodegradables fabricadas a partir de almidón de papa confirmando los efectos en sus características físicas y propiedades activas en función del porcentaje de AgNp, las cuales pueden ser aprovechadas para la fabricación de materiales activos

The Role of the Unfolded Protein Response on Renal Lipogenesis in C57BL/6 Mice.

Renal injury observed in several pathologies has been associated with lipid accumulation in the kidney. While it has been suggested that the accumulation of renal lipids depends on free fatty acids released from adipose tissue, it is not known whether in situ renal lipogenesis due to endoplasmic reticulum (ER) stress contributes to kidney injury. The aim of the present study was to elucidate the role of pharmacological ER stress in renal structure and function and its effect on renal lipid metabolism of C57BL/6 mice. ER stress increased serum creatinine and induced kidney structural abnormalities. Tunicamycin-administered mice developed hyperinsulinemia, augmented lipolysis and increased circulating leptin and adiponectin. Renal unfolded protein response (UPR) gene expression markers, the lipogenic transcription factor SREBP1 and the phosphorylation of eIF2α increased 8 h after tunicamycin administration. At 24 h, an increase in BiP protein content was accompanied by a reduction in p-eIF2α and increased SREBP-1 and FASn protein content, in addition to a significant increase in triglyceride content and a reduction in AMPK. Thus, ER stress induces in situ lipid synthesis, leading to renal lipid accumulation and functional alterations. Future pharmacological and/or dietary strategies must target renal ER stress to prevent kidney damage and the progression of metabolic diseases