Isotopic constraints confirm the significant role of microbial nitrogen oxides emissions from the land and ocean environment

Nitrogen oxides (NO_x, the sum of nitric oxide (NO) and N dioxide (NO₂)) emissions and deposition have increased markedly over the past several decades, resulting in many adverse outcomes in both terrestrial and oceanic environments. However, because the microbial NO_x emissions have been substantially underestimated on the land and unconstrained in the ocean, the global microbial NO_x emissions and their importance relative to the known fossil-fuel NO_x emissions remain unclear. Here we complied data on stable N isotopes of nitrate in atmospheric particulates over the land and ocean to ground-truth estimates of NO_x emissions worldwide. By considering the N isotope effect of NO_x transformations to particulate nitrate combined with dominant NO_x emissions in the land (coal combustion, oil combustion, biomass burning and microbial N cycle) and ocean (oil combustion, microbial N cycle), we demonstrated that microbial NO_x emissions account for 24 ± 4%, 58 ± 3% and 31 ± 12% in the land, ocean and global environment, respectively. Corresponding amounts of microbial NO_x emissions in the land (13.6 ± 4.7 Tg N yr⁻¹), ocean (8.8 ± 1.5 Tg N yr⁻¹) and globe (22.5 ± 4.7 Tg N yr⁻¹) are about 0.5, 1.4 and 0.6 times on average those of fossil-fuel NO_x emissions in these sectors. Our findings provide empirical constraints on model predictions, revealing significant contributions of the microbial N cycle to regional NO_x emissions into the atmospheric system, which is critical information for mitigating strategies, budgeting N deposition and evaluating the effects of atmospheric NO_x loading on the world.     

按劳分配与按劳动力价值分配

本文认为在社会主义初级阶段,个人消费品的基本分配方式是按劳动力价值分配。因为,在现阶段,劳动者个人同生产物质条件发生一定程度的分离,国家与劳动者个人交换,只能遵循“等价交换”的原则;在现阶段,劳动者既是国家的主人,又是国家的“雇员”,其收入分配,既按劳动力价值分配;又参与剩余价值的分割,并不否认劳动者主人翁地位     

Removing barriers and building bridges: American deaf interns teaching Chinese deaf children.

Two deaf American student-teaching M.A. candidates did an internship at a school for the Deaf in China. This was the first such internship ever done in China. Critical procedures for establishing international internships are described; cultural and educational experiences and the accommodations made to guarantee the success of such internships are analyzed, including issues related to communication modality, educational philosophy, expectations for deaf learners, and teaching methods. The views of both interns, and those of two teacher educators one American and one Chinese, are included.     

Understanding the Experiences of Beginning Secondary School Teachersy

This paper reports a study which sought to obtain deeper insights into the experiences of beginning secondary school teachers in Swaziland during 1997. Out of a sample of 48 beginning teachers, 28 participated in the study. They were invited to complete a questionnaire and were also visited in their schools where they were interviewed and observed during teaching practice. The paper describes the experiences of these teachers. The study found that, while there were several common concerns and experiences during the first year of teaching, there were also some significant different experiences. The paper discusses some implications of the study for teacher education.     

青少年篮球队员投篮稳定性的研究

对青少年篮球队员投篮稳定性的影响主要有心理因素和技术因素,对前者可采取程序训练法和情绪调控训练来加以改善;对后者则需要抓好投篮技术动作、提高投篮技术动作的动力定型、提高技战术组合能力。