Enfoques de investigación en problemas verbales aritméticos aditivos

A main field in the current research in Mathematics Education is the work with arithmetical word problem solving, which is both interesting and useful. There is ample previous work on this topic and it has received a very systematic treatment from different focuses. Researchers getting involved in this field need to know previous works and current focuses to clarify their research goals. In this study we offer a review about previous research done on difficulties with arithmetical word problems

Patterns and barriers for innovation and R&D cooperation between Argentine and Spanish firms

10 tables, 4 figures, 27 pagesThis paper examines co-operative innovation and research and development (R&D) behaviour between Argentine and Spanish firms. Based on theoretical perspectives from the literature, we surveyed a sample of 540 Argentine and Spanish firms believed to have cooperated for technological innovation. We present empirical evidence based on 104 firms of patterns of cooperation in several processes and out-puts, highlighting firm characteristics, the motives of the collaborating parties, types of partners and R&D and innovation activities, leadership, and obstacles to cooperation. Our results reveal that the determinants of success differ considerably among countries depending on the sector, the firm specific characteristics and funding. These differences have important implications for public policy and instruments to support R&D and innovation activities

Innovation in Early music festivals. domains, strategies and outcomes

This chapter takes an in-depth look at innovation in cultural festivals, in particular in early music festivals, which is a type of festival aimed at a generally local and minority audience. It identifies and analyses types of innovations, the strategies used by early music festivals to innovate and the results of these innovations in the framework of a collaboration with the European Early Music Network, whose members, festival directors, agreed to participate in the survey designed for this purpose. Different types of product, production and pre-production process, marketing and communication innovations are identified but also maintain traditional products and communication channels for their most loyal audience. The analysis shows that early music festivals engage in a range of innovations and employ a meaningful combination of innovation strategies with diverse stakeholders. Innovation efforts have led to several intangible and tangible improvements, including increased prestige and bigger and more diverse audiences. Although some of the innovations identified are common to other cultural festivals, many product innovations depend on musicology research; therefore, similar to other science-based sectors, relationships with researchers are very important

Chitosan application in maize (Zea mays) to counteract the effects of abiotic stress at seedling level

Worldwide, the conditions of biotic and abiotic stresses adversely affect the potential production of maize. Drought or heat facilitate the infection with fungi such as Aspergillus flavus and Fusarium moniliforme, and consequently increase the production of mycotoxins. There are several strategies for managing the problem, but in the future, people will prefer the cleaner and cheaper technology. The use of elicitors for protection of corn can be considered a cheap and clean technology. Chitosan elicitor is a linear polysaccharide produced commercially by deacetylation of chitin. It has been reported that this elicitor induce phytoalexin accumulation in plant tissue. Application of chitosan to seeds in rice significantly increased rice yield. About this, there are no reports in corn. For this reason, the aim of this study was to determine the protective effect of chitosan in maize seedlings subjected to abiotic stresses. To this end, three treatments were tested (a negative control, a positive control, and a group coated with chitosan solution) under four abiotic stresses conditions since their germination stage: drought, moisture, acid pH and alkaline pH. During five weeks, the seedlings growth was evaluated by measuring their total length, the length of leaves, stems and the thickness of these and presence of fungi. Positive effect was observed in seeds treated with chitosan or stressed with acidic pH in dimensions of seedlings and there was no fungal growth.Key words: Abiotic stress, Zea mays, chitosan, pH, drought, humidit

Peroxidase expression in a cereal cyst nematode (Heterodera avenae) resistant hexaploid wheat line.

The incompatible interaction between plant and pathogen is often determined by the hypersensitive reaction (HR). This response is associated with accumulation of reactive oxygen species (ROS), which results in adverse growth conditions for pathogens. Two major mechanisms involving either NADPH oxidases or peroxidases have been proposed for generation of ROS. Peroxidases (PER, EC 1.11.1.7), present in all land plants, are members of a large multigenic family with high number of isoforms involved in a broad range of physiological processes. PER genes, which are expressed in nematode feeding sites, have been identified in several plant species (Zacheo et al. 1997). A strong correlation between HR and PER activities at four and seven days post nematode infection, was detected in roots of wheat lines carrying Cre2, Cre5 (from Ae. ventricosa) or Cre7 (from Ae. triuncialis) Heterodera avenae resistance genes (Andrés et al. 2001; Montes et al. 2003, 2004). We have studied changes in root of peroxidase mRNAs levels after infection by H. avenae of a wheat/Ae. ven¬tricosa introgression line (H-93-8) carrying Cre2 (Delibes et al. 1993). We also report and classify the predicted protein sequences derived from complete peroxidase transcripts

Motives for inter-firm cooperation on R&D and innovation: empirical evidence from Argentine and Spain

Ingenio Working Paper SeriesMotives and determinants supporting inter-firm technological cooperation have been extensively investigated in developed countries but scarcely addressed in developing countries. This paper addresses these issues, investigating empirically several factors influencing the likelihood to cooperate on R&D and innovation between Argentine and Spanish firms, their strategic motives and firms characteristics which influence cooperation. We draw upon data collected through a survey of 104 firms and complementary information gathered from 19 in-depth interviews, combining both qualitative and quantitative methodology. Results of a multinomial regression and the interviews show that the probability to cooperate increases with the firm size and exportation activities and decrease with the firm age whereas, opposite to literature findings, technological intensity of the firm is a non-significant variable. While for Argentine firms the principal motives are cost reduction and the possibilities for improving learning and capabilities, access to new knowledge for technological development and the search for market opportunities are the principal motives for firms located in Spain. Results of interviews also indicates that firm-specific motives and expectations may differ considerably according the activity sector, with relevant implication for norms and regulation policies in each country.N

Annual Legumes as an Alternative for Animal Feeding in Cuba

Studies conducted in Cuba have demonstrated the importance of the agronomic and nutritional performance of the species Vigna unguiculata (cowpea), Canavalia ensiformis (jackbean), Stizolobium niveum (mucuna), Lablab purpureus (dolicho) and Glycine max (soybean) as feed sources for non-ruminant species. Under Cuban tropical conditions, and with minimum agricultural inputs, jackbean, dolicho and mucuna have attained forage yields between 4 and 6 t dry matter (DM)/ha and grain yields between 2.57 and 3.41 t/ha and cowpea and soybean have given yields of between 1 and 2 t/ha (Díaz 2000). This study was carried out to determine the chemical composition of grains and forages of these annual legumes in relation to their use in animal feeding