“Seeking Information from the Lips of People”: oral history in the archives of Qatar and the Gulf region

The turn to oral history in Qatar and the Arabian (also known as Persian) Gulf is not a rejection of traditional archival authority as has been the case in other parts of the world. In the Gulf, oral history has been embraced out of a desire to fill the silences of the largely unwritten record attributable to previous low levels of literacy and strong oral traditions in the region. Today, oral history is seen as the best method to capture details about traditional ways of life during the pre-oil era. After discussing archival concerns about the evidentiary nature of oral histories, this paper explores how it has come to be a crucial documentation tool in the Gulf, adapted to the specific nation building and cultural heritage priorities of the region.     

Applying LDA Topic Modeling in Communication Research: Toward a Valid and Reliable Methodology

ABSTRACT

Latent Dirichlet allocation (LDA) topic models are increasingly being used in communication research. Yet, questions regarding reliability and validity of the approach have received little attention thus far. In applying LDA to textual data, researchers need to tackle at least four major challenges that affect these criteria: (a) appropriate pre-processing of the text collection; (b) adequate selection of model parameters, including the number of topics to be generated; (c) evaluation of the model’s reliability; and (d) the process of validly interpreting the resulting topics. We review the research literature dealing with these questions and propose a methodology that approaches these challenges. Our overall goal is to make LDA topic modeling more accessible to communication researchers and to ensure compliance with disciplinary standards. Consequently, we develop a brief hands-on user guide for applying LDA topic modeling. We demonstrate the value of our approach with empirical data from an ongoing research project.     

Serrated lithium fluoride nanofibers-woven interlayer enables uniform lithium deposition for lithium-metal batteries

The uncontrollable formation of Li dendrites has become the biggest obstacle to the practical application of Li-metal anodes in high-energy rechargeable Li batteries. Herein, a unique LiF interlayer woven by millimeter-level, single-crystal and serrated LiF nanofibers (NFs) was designed to enable dendrite-free and highly efficient Li-metal deposition. This high-conductivity LiF interlayer can increase the Li⁺ transference number and induce the formation of ‘LiF–NFs-rich’ solid–electrolyte interface (SEI). In the ‘LiF–NFs-rich’ SEI, the ultra-long LiF nanofibers provide a continuously interfacial Li⁺ transport path. Moreover, the formed Li–LiF interface between Li-metal and SEI film renders low Li nucleation and high Li⁺ migration energy barriers, leading to uniform Li plating and stripping processes. As a result, steady charge–discharge in a Li//Li symmetrical cell for 1600 h under 4 mAh cm⁻² and 400 stable cycles under a high area capacity of 5.65 mAh cm⁻² in a high-loading Li//rGO–S cell at 17.9 mA cm⁻² could be achieved. The free-standing LiF–NFs interlayer exhibits superior advantages for commercial Li batteries and displays significant potential for expanding the applications in solid Li batteries.     

财政补贴、融资约束与高端装备制造企业研发投入

选取2010-2017年我国高端装备制造业上市公司的微观数据,考察财政补贴、融资约束与企业研发投入之间的关系.研究结果表明:财政补贴对高端装备制造企业的研发投入强度具有显著的促进作用,且这种促进作用在国有企业、年轻型企业和成长型企业中更明显;而融资约束不仅直接对高端装备制造企业的研发投入强度产生抑制作用,还抑制财政补贴...