We present a study that examines how a social media activism campaign aimed
at improving gender diversity within engineering gained and maintained momentum
in its early period. We examined over 50,000 Tweets posted over the first ~75
days of the #ILookLikeAnEngineer campaign and found that diverse participation
- of types of users - increased activity at crucial moments. We categorize
these triggers into four types: 1) Event-Driven: Alignment of the campaign with
offline events related to the issue (Diversity SFO, Disrupt, etc.); 2)
Media-Driven: News coverage of the events in the media (TechCrunch, CNN, BBC,
etc.); 3) Industry-Driven: Web participation in the campaign by large
organizations (Microsoft, Tesla, GE, Cisco, etc.); and 4) Personality-Driven:
Alignment of the events with popular and/or known personalities (e.g. Isis
Anchalee; Michelle Sun; Ada Lovelace.) This study illustrates how one mechanism
- triggering - supports connective action in social media campaign.

研究社交媒体行动主义活动如何利用触发机制来促进获得和维持动力，以实现工程领域的性别多样化，发现多样化的参与类型会在至关重要的时刻增加活动性。触发机制分为四种类型：与离线事件对齐，媒体报道，行业参与和知名人物对齐。

社交媒体如何通过多元用户和活动引发联合行动：来自 Twitter Hashtag 活动 #ILookLikeAnEngineer 的启示

How Diverse Users and Activities Trigger Connective Action via Social  Media: Lessons from the Twitter Hashtag Campaign #ILookLikeAnEngineer

The ETAS model is widely employed to model the spatio-temporal distribution
of earthquakes, generally using spatially invariant parameters. We propose an
efficient method for the estimation of spatially varying parameters, using the
Expectation-Maximization (EM) algorithm and spatial Voronoi tessellation
ensembles. We use the Bayesian Information Criterion (BIC) to rank inverted
models given their likelihood and complexity and select the best models to
finally compute an ensemble model at any location. Using a synthetic catalog,
we also check that the proposed method correctly inverts the known parameters.
We apply the proposed method to earthquakes included in the ANSS catalog that
occurred within the time period 1981-2015 in a spatial polygon around
California. The results indicate a significant spatial variation of the ETAS
parameters. We find that the efficiency of earthquakes to trigger future ones
(quantified by the branching ratio) positively correlates with surface heat
flow. In contrast, the rate of earthquakes triggered by far-field tectonic
loading or background seismicity rate shows no such correlation, suggesting the
relevance of triggering possibly through fluid-induced activation. Furthermore,
the branching ratio and background seismicity rate are found to be uncorrelated
with hypocentral depths, indicating that the seismic coupling remains invariant
of hypocentral depths in the study region. Additionally, triggering seems to be
mostly dominated by small earthquakes. Consequently, the static stress change
studies should not only focus on the Coulomb stress changes caused by specific
moderate to large earthquakes but also account for the secondary static stress
changes caused by smaller earthquakes.

本文提出一种使用期望最大化（EM）算法和空间 Voronoi 镶嵌集进行空间变化参数估计的有效方法，应用于模拟地震空间 - 时间分布，结果发现地震触发效率正相关于地表热流量且大部分是小地震所致所以静态应力变化研究不仅应关注中等到大型地震引起的库仑应力变化，还应考虑更小地震引起的次级静态应力变化。