Sustainably feeding the world's growing population is a challenge, and closing yield gaps (that is, differences between farmers' yields and what are attainable for a given region) is a vital strategy to address this challenge. The magnitude of yield gaps is particularly large in developing countries where smallholder farming dominates the agricultural landscape. Many factors and constraints interact to limit yields, and progress in problem-solving to bring about changes at the ground level is rare. Here we present an innovative approach for enabling smallholders to achieve yield and economic gains sustainably via the Science and Technology Backyard (STB) platform. STB involves agricultural scientists living in villages among farmers, advancing participatory innovation and technology transfer, and garnering public and private support. We identified multifaceted yield-limiting factors involving agronomic, infrastructural, and socioeconomic conditions. When these limitations and farmers' concerns were addressed, the farmers adopted recommended management practices, thereby improving production outcomes. In one region in China, the five-year average yield increased from 67.9% of the attainable level to 97.0% among 71 leading farmers, and from 62.8% to 79.6% countywide (93,074 households); this was accompanied by resource and economic benefits.

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Double cropping of wheat and maize is common on the North China Plain, but it provides limited income to rural households due to the small farm sizes in the region. Local farmers in Quzhou County have therefore innovated their production system by integration of watermelon as a companion cash crop into the system. We examine the economic performance and sustainability of this novel intercropping system using crop yield data from 2010 to 2012 and farm household survey data collected in 2012. Our results show that the gross margin of the intercropping system exceeded that of the double cropping system by more than 50% in 2012. Labor use in the intercropping system was more than three times that in double cropping. The lower returns per labor hour in intercropping, however, exceeded the average off-farm wage in the region by a significant margin. Nutrient surpluses and irrigation water use are significant larger under the intercropping system. We conclude that the novel wheat-maize/watermelon intercropping system contributes to rural poverty alleviation and household-level food security, by raising farm incomes and generating more employment, but needs further improvement to enhance its sustainability.

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Background] Recent research on mining app reviews for software evolution indicated that the elicitation and analysis of user requirements can benefit from supplementing user reviews by data from other sources. However, only a few studies reported results of leveraging app changelogs together with app reviews.[Aims] Motivated by those findings, this exploratory experimental study looks into the role of app changelogs in the classification of requirements derived from app reviews. We aim at understanding if the use of app changelogs can lead to more accurate identification and classification of functional and non-functional requirements from app reviews. We also want to know which classification technique works better in this context. [Method]We did a case study on the effect of app changelogs on automatic classification of app reviews. Specifically, manual labeling, text preprocessing, and four supervised machine learning algorithms were applied to a series of experiments, varying in the number of app changelogs in the experimental data. [Results] We compared the accuracy of requirements classification from app reviews, by training the four classifiers with varying combinations of app reviews and changelogs. Among the four algorithms, Naïve Bayes was found to be more accurate for categorizing app reviews.[Conclusions] The results show that official app changelogs did not contribute to more accurate identification and classification of requirements from app reviews. In addition, Naïve Bayes seems to be more suitable for our further research on this topic. CCS CONCEPTS• Software and its engineering → Requirements analysis

Three-dimensional (3D) printing as a powerful manufacturing platform has been increasingly used in biomedical engineering over the past two decades. Such technologies greatly improve our ability to fabricate a variety of complex and customized biomedical products accurately, efficiently, economically, and with high reproducibility through layer-by-layer positioning of materials, biomolecules, or even living cells in the products. Despite the impressive progress of 3D printing in biomedical engineering, more and greater efforts are needed to develop new and much improved biomedical products via 3D printing. In particular, many challenges in 3D printing processes, materials, and applications must be addressed in order to make available high-quality products and novel products to millions of patients. Addressing these challenges requires the integration of advances in physics, materials science, engineering, biological sciences, and medicine. In this article, we provide a comprehensive and up-to-date review of 3D printing and its applications in the biomedical field. We systematically present and discuss 3D printing technologies, materials, cells, and applications that are associated with biomedical engineering. Additionally, 4D printing and bioprinting are reviewed. We give our analysis and put forward our views on the challenges for 3D printing in biomedical engineering and also possible future developments. It is apparent that 3D printing plays a more and more important role in biomedical engineering and can create a diverse range of high-value biomedical products. This comprehensive review can help to understand the current status and identify future directions of 3D printing in biomedical engineering, as well as moving 3D printing toward manufacturing newer and better biomedical products.

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