Abundancia de juveniles de camarones peneidos comerciales en la zona norte de Laguna Madre, México

Monthly samplings were carried out during August, 2005 to November, 2006 to analizing the changes of the abundance of commercial juvenile penaeid shrimps in the North part of Laguna Madre, Tamaulipas. In every nine points a night trawl were carried out using a seine net of mesh size of 1.25 cm and 6 m length of bottom rope. Three commercial penaeid shrimp species were found and each one presented high abundance values for different periods of the year. Brown shrimp, Farfantepenaeus aztecus, in April-May period; pink shrimp, Farfantepenaeus dourarum, in DecemberJanuary, and the white shrimp, Litopenaeus setiferus in July and September. These results showed that different species presented a differential temporal use in Laguna Madre.Se tomaron muestras mensuales de agosto del 2005 a noviembre del 2006, para analizar los cambios de abundancia de juveniles de camarones peneidos comerciales en la parte norte de Laguna Madre, Tamaulipas. En cada una de las nueve estaciones de muestreo se realizó un arrastre nocturno, utilizando una red tipo chinchorro, de tamaño de malla de 1.25 cm y seis metros de longitud de relinga inferior. Se observaron tres especies de peneidos comerciales y cada una de ellas tuvo sus valores más altos de abundancia en diferentes periodos del año. El camarón café, Farfantepenaeus aztecus fue más abundante de abril-mayo; el camarón rosado, Farfantepenaeus dourarum en diciembreenero y el camarón blanco, Litopenaeus setiferus en julio y septiembre. Estos resultados muestran que estas especies tienen un uso temporal diferencial en Laguna Madre, Tamaulipas

Contributions to the INIFAP technology transfer 35 years after its creation / Contribuições para a transferência de tecnologia INIFAP 35 anos após a sua criação

The main contributions that INIFAP has made in the transfer of technologies and knowledge, in support of the rural population of Mexico, are presented, the most outstanding models within the national and international scope that researchers have put into operation and their main results are detailed. Undoubtedly, the institutional contributions to the programs of the Ministry of Agriculture and Rural Development have marked a watershed between the traditional models or what "what occurred to him" to the researcher in contrast to the participatory and inclusive models to contribute to the substantial improvement of the productive processes, the family economy and for the agribusiness

Effectiveness of post-fire soil erosion mitigation treatments: a systematic review and meta-analysis

Wildfires are known to be one of the main causes of soil erosion and land degradation, and their impacts on ecosystems and society are expected to increase in the future due to changes in climate and land use. It is therefore vital to mitigate the increased hydrological and erosive response after wildfires to maintain the sustainability of ecosystems and protect the values at risk downstream from the fire-affected areas. Soil erosion mitigation treatments have been widely applied after wildfires but assessment of their effectiveness has been limited to local and regional-scale studies, whose conclusions may depend heavily on site-specific conditions. To overcome this limitation, a meta-analysis approach was applied to investigations of post-wildfire soil erosion mitigation treatments published in peer-reviewed journals. A meta-analysis database was compiled that consisted of 53 and 222 pairs of treated/untreated observations on post-fire runoff and erosion, respectively, extracted from 34 publications indexed in Scopus. The overall effectiveness of mitigation treatments, expressed as the quantitative metric ‘effect size’, was determined for both the runoff and erosion observations, and further analyzed for four different types of treatments (cover-based, barriers, seeding, and chemical treatments). The erosion observations involving cover-based treatments were analyzed for differences in effectiveness between 3 different types of mulch materials (straw, wood-based, and hydromulch) as well as between different application rates of straw and wood materials. Finally, the erosion observations were also analyzed for the overall effectiveness of post-fire year, burn severity, rainfall amount and erosivity, and ground cover. The meta-analysis results show that all four types of treatments significantly reduced post-fire soil erosion, but that only the cover and barrier treatments significantly reduced post-fire runoff. From the three different cover treatments, straw and wood mulches were significantly more effective in mitigating erosion than hydromulch. In addition, the effectiveness of both straw and wood mulches depended on their application rates. Straw mulching was less effective at rates below than above 200 g m−2, while mulching with wood materials at high rates (1300 to 1750 g m−2) produced more variable outcomes than lower rates. Results also suggest that the overall effectiveness of the treatments was greatest shortly after fire, in severely burned sites, providing or promoting the development of ground cover over 70%, and that it increased with increasing rainfall erosivity. It can be concluded that, in overall terms, the application of the studied post-fire erosion mitigation treatments represented a better choice than doing nothing, especially in sites where erosion is high. However, the meta-analysis highlights under-representation of studies on this topic outside of the USA, Spain and Portugal. It was also observed that most of the studies were conducted at hillslope scale and tested mulching (namely straw, wood and hydromulch) and/or barriers, while larger scales and other treatments were scarcely addressed. Further efforts need to be made in testing, from field and modeling studies, combinations of existing and/or emerging erosion mitigation treatments to ensure that the most adequate measures are applied after fires.publishe

A mathematical model for Babesiosis disease in bovine and tick populations

In this paper, we analyze the Babesiosis transmission dynamics on bovine and tick populations. Ticks play a role of infec- tious agents and vector of the protozoan Babesia hemo-parasite. In this sense, we set out a mathematical model with constant size population for the evolution of the infected bovines with Babesiosis and analyze its qualitative dynamics. Statistical data are used to estimate some of the parameters of the model. Numerical simulations of the model varying the parameters show different scenarios about the spread of the diseaseJose C. Valverde thanks Junta de Comunidades de Castilla-La Mancha and Ministerio de Ciencia e Innovacion of Spain for their support for this work through the grants PEII09-0184-7802 and MTM2008-03679/MTM, respectively.Aranda, DF.; Trejos, DY.; Valverde, JC.; Villanueva Micó, RJ. (2012). A mathematical model for Babesiosis disease in bovine and tick populations. Mathematical Methods in the Applied Sciences. 35(3):249-256. doi:10.1002/mma.1544S249256353Brauer, F., & Castillo-Chávez, C. (2001). Mathematical Models in Population Biology and Epidemiology. Texts in Applied Mathematics. doi:10.1007/978-1-4757-3516-1Hethcote, H. W. (2000). The Mathematics of Infectious Diseases. SIAM Review, 42(4), 599-653. doi:10.1137/s0036144500371907Dietz, K. (1993). The estimation of the basic reproduction number for infectious diseases. Statistical Methods in Medical Research, 2(1), 23-41. doi:10.1177/096228029300200103Simon, C. P., & Jacquez, J. A. (1992). Reproduction Numbers and the Stability of Equilibria of SI Models for Heterogeneous Populations. SIAM Journal on Applied Mathematics, 52(2), 541-576. doi:10.1137/0152030Thieme, H. R. (2003). Mathematics in Population Biology. doi:10.1515/9780691187655Esteva, L., & Vargas, C. (2000). Influence of vertical and mechanical transmission on the dynamics of dengue disease. Mathematical Biosciences, 167(1), 51-64. doi:10.1016/s0025-5564(00)00024-