Effect of model root exudate on denitrifier community dynamics and activity at different water-filled pore space levels in a fertilised soil

Although a “rhizosphere effect” on denitrification rates has been established, a clear understanding of the effects of exudate addition on denitrifier community dynamics remains elusive. A microcosm experiment was designed to explore the interaction between exudate addition and soil moisture on community dynamics and denitrification rates. Artificial root exudate at 5 different carbon concentrations was added daily to soil microcosms at contrasting target WFPS (50, 70 and 90%). After a 7-day period, total denitrification and N2O emission rates were measured and community dynamics assessed using molecular methods. The response of denitrifier genes to exudate addition was different, with nirS and nosZ-I showing a stronger effect than nirK and nosZ-II. Distinct community structures were observed for nirS and nosZ-I at 90% target WFPS when compared to 50% and 70%. NirS denitrifier population size showed a ca. 5-fold increase in gene copy number at 90% WFPS when exudate was added at the highest C input. Significant total denitrification and N2O emission rates were observed only at 90% WFPS, which increased with C input. Our study improves the understanding of the complex interaction between microbial communities, the abiotic environment and process rates which can inform management practices aimed at increasing complete denitrification and controlling greenhouse gas production from agriculture

Corrigendum to "Biodegradation of polyester polyurethane during commercial composting and analysis of associated fungal communities" [Bioresour. Technol. 158 (2014) 374-377].

The authors regret to inform that the name of the second author was misspelt in the article. Please read the name as Petrus Nzerem instead of Petrus Nzeram. The corrected author name is shown above. The authors would like to apologise for any inconvenience caused

Simulador de negocios Capsim: planeación estratégica en la industria de los sensores

Se describen las decisiones y el resultado de la estrategia implementada por Andrews, empresa del simulador de negocios CAPSTONE. En el primer capítulo se presenta el marco teórico sobre estrategia, el cual se encuentra conformado por teorías que dan herramientas para la solución de diferentes casos que se describirán. El segundo capítulo describe la industria de sensores, la cual es utilizada en el simulador de CAPSTONE, además se describe la planeación y estrategia general de la compañía compuesta por la misión, visión y estructura organizacional. Del capítulo tres al seis se analizan los resultados obtenidos durante la administración de la compañía, los cuales abarcan de los años 2020 al 2027 en las áreas de finanzas, producción, mercadotecnia, calidad, recursos humanos e investigación y desarrollo. Por último, en el séptimo capítulo se presentan las conclusiones sobre el desempeño de la empresa Andrews y la experiencia del uso del simulador de negocios CAPSTONE en la vida profesional del equipo

Structural design techniques applied in astronomical instruments

International audienceWe present in this article some of the techniques applied at the Instituto de Astronomía of the Universidad Nacional Autónoma de México (IA-UNAM) to the mechanical structural design for astronomical instruments. With this purpose we use two recent projects developed by the Instrumentation Department. The goal of this work is to give guidelines about support structures design for achieving a faster and accurate astronomical instruments design. The main guidelines that lead all the design stages for instrument subsystems are the high-level requirements and the overall specifications. From these, each subsystem needs to get its own requirements, specifications, modes of operation, relative position, tip/tilt angles, and general tolerances. Normally these values are stated in the error budget of the instrument. Nevertheless, the error budget is dynamic, it is changing constantly. Depending on the manufacturing accuracy achieved, the error budget is again distributed. That is why having guidelines for structural design helps to know some of the limits of tolerances in manufacture and assembly. The error budget becomes then a quantified way for the interaction between groups; it is the key for teamwork