Quantitative Analysis Of Contribution Research Articles

Heat‐stress‐induced fertility loss in summer maize (Zea mays L.): Quantitative analysis of contributions from developmental and physiological damage to pollen

AbstractIn recent years, the frequency and intensity of exposure to heat stress have increased gradually, seriously hampering the production of maize. This paper presents a study designed to analyze how the development, physiology and dispersal of pollen from the heat‐resistant maize variety Zhengdan958 and the heat‐sensitive maize variety Xianyu335 are affected by exposure to heat stress during the tasselling stage. Our results showed That exposure to heat stress significantly increased the antioxidant enzyme activity in pollen. Upon visual inspection of the pollen, we found that the lower water content had given rise to wrinkles in the pollen surface, sunken germination pores, and morphological deformations. In addition, the anther dehiscence process was hindered, resulting in a reduced amount of pollen being dispersed. We also found elevated levels of abscisic acid (ABA), jasmonic acid (JA) and its derivatives, indole acetic acid (IAA) and gibberellin‐3 (GA3) in heat‐pollens, as well as elevated ratios of IAA to ABA and ABA to GA3. Ultimately impaired pollen fertility. Summarizing, our experiment revealed that reduced pollen quantity and quality are significant contributors to fertility losses in summer maize exposed to heat stress at anthesis, and we hope that our analysis of the physiological mechanisms involved can contribute to the development of crop management measures aimed at countering the increasingly detrimental effects of heat stress on the production of summer maize.

Border Sharing – a Quantitative Analysis of Contributions to FRONTEX 2012–2018

ABSTRACT From 2011, due to war, conflict, and ensuing unrest, both in the Middle East and Africa, the European Union’s southern external borders were confronted with an influx of migrants and refugees. At its height, the influx became known as a migration (or refugee) crisis and the European Border and Coast Guard Agency (FRONTEX) was perceived as a pivotal partner in crisis management at the borders. FRONTEX does not avail of its own operators nor materiel, and, consequently, Schengen member states and Schengen Associated Countries were requested to contribute personnel and equipment for operations. From 2012 to 2018, this article analyzes the member states’ burden-sharing behavior regarding their contributions to European Border Guard Teams and Technical Equipment Pool. Our findings include both over- and under-contributors. As the sum total of contributions over all member states is high, it could be concluded, member states derive common benefits from border management. However, results also show that, as compared to others, member states situated at the European Union’s Southern and Eastern borders, on average, are over-contributing. Moreover, contributions from individual member states fluctuate over time. Apparently, the acquired benefits are not always perceived in the same way.

Role of interatomic bonding in the mechanical anisotropy and interlayer cohesion of CSH crystals

Atomic scale properties of calcium silicate hydrate (CSH), the main binding phase of hardened Portland cement, are not well understood. Over a century of intense research has identified almost 50 different crystalline CSH minerals which are mainly categorized by their Ca/Si ratio. The electronic structure and interatomic bonding in four major CSH crystalline phases with structures close to those found in hardened cement are investigated via ab initio methods. Our result reveals the critical role of hydrogen bonding and importance of specifying precise locations for water molecules. Quantitative analysis of contributions from different bond types to the overall cohesion shows that while the SiO covalent bonds dominate, the hydrogen bonding and CaO bonding are also very significant. Calculated results reveal the correlation between bond topology and interlayer cohesion. The overall bond order density (BOD) is found to be a more critical measure than the Ca/Si ratio in classifying different CSH crystals.