On effectiveness of wiretap programs in mapping social networks

Snowball sampling methods are known to be a biased toward highly connected actors and consequently produce core-periphery networks when these may not necessarily be present. This leads to a biased perception of the underlying network which can have negative policy consequences, as in the identification of terrorist networks. When snowball sampling is used, the potential overload of the information collection system is a distinct problem due to the exponential growth of the number of suspects to be monitored. In this paper, we focus on evaluating the effectiveness of a wiretapping program in terms of its ability to map the rapidly evolving networks within a covert organization. By running a series of simulation-based experiments, we are able to evaluate a broad spectrum of information gathering regimes based on a consistent set of criteria. We conclude by proposing a set of information gathering programs that achieve higher effectiveness then snowball sampling, and at a lower cost. Maksim Tsvetovat is an Assistant Professor at the Center for Social Complexity and department of Public and International Affairs at George Mason University, Fairfax, VA. He received his Ph.D. from the Computation, Organizations and Society program in the School of Computer Science, Carnegie Mellon University. His dissertation was centered on use of artificial intelligence techniques such as planning and semantic reasoning as a means of studying behavior and evolution of complex social networks, such as these of terrorist organizations. He received a Master of Science degree from University of Minnesota with a specialization in Artificial Intelligence and design of Multi-Agent Systems, and has also extensively studied organization theory and social science research methods. His research is centered on building high-fidelity simulations of social and organizational systems using concepts from distributed artificial intelligence and multi-agent systems. Other projects focus on social network analysis for mapping of internal corporate networks or study of covert and terrorist orgnaizations. Maksim’s vita and publications can be found on Kathleen M. Carley is a professor in the School of Computer Science at Carnegie Mellon University and the director of the center for Compuational Analysis of Social and Organizational Systems (CASOS) which has over 25 members, both students and research staff. Her research combines cognitive science, social networks and computer science to address complex social and organizational problems. Her specific research areas are dynamic network analysis, computational social and organization theory, adaptation and evolution, text mining, and the impact of telecommunication technologies and policy on communication, information diffusion, disease contagion and response within and among groups particularly in disaster or crisis situations. She and her lab have developed infrastructure tools for analyzing large scale dynamic networks and various multi-agent simulation systems. The infrastructure tools include ORA, a statistical toolkit for analyzing and visualizing multi-dimensional networks. ORA results are organized into reports that meet various needs such as the management report, the mental model report, and the intelligence report. Another tool is AutoMap, a text-mining systems for extracting semantic networks from texts and then cross-classifying them using an organizational ontology into the underlying social, knowledge, resource and task networks. Her simulation models meld multi-agent technology with network dynamics and empirical data. Three of the large-scale multi-agent network models she and the CASOS group have developed in the counter-terrorism area are: BioWar a city-scale dynamic-network agent-based model for understanding the spread of disease and illness due to natural epidemics, chemical spills, and weaponized biological attacks; DyNet a model of the change in covert networks, naturally and in response to attacks, under varying levels of information uncertainty; and RTE a model for examining state failure and the escalation of conflict at the city, state, nation, and international as changes occur within and among red, blue, and green forces. She is the founding co-editor with Al. Wallace of the journal Computational Organization Theory and has co-edited several books and written over 100 articles in the computational organizations and dynamic network area. Her publications can be found at: http://www.casos.cs.cmu.edu/bios/carley/publications.php     

Initial organic geochemical investigation on Late Neoproterozoic-Early Cambrian sediments in the Yangtze region, China

Totally 19 samples of typical Upper Proterozoic-Lower Cambrian sedimentary rocks were collected and analyzed for an organic geochemical investigation. Almost all these rocks have high TOCs, super-maturities and similar biomarker distribution. As an exception, however, the Sinian Nantuo Tillite shows much lower TOCs and little phytane and pristane in comparison with those in other strata, which implies a very faint photosynthetic process, and a restricted euphotic zone and quite limited sunlight within the sedimentary water column during the Sinian glaciation age in the western Yangtze region providing an evidence for palaeo-oceanic environment of the Neoproterozoic Snowball Earth age.     

既是历史学的,又是人类学的——再读《雪球:汉民族的人类学分析》有感

历史人类学在中国有着广泛的应用前景。由徐杰舜教授主编的《雪球 :汉民族的人类学分析》即是应用历史人类学的理论与方法来研究汉族历史和文化的创新之作 ,从学术上来说 ,《雪球》在对汉民族作人类学分析时 ,既强调汉民族文化的历史向度 ,也用人类学理论对汉族文化作了详细的分析 ,它既是历史学的 ,又是人类学的。《雪球》一书的出版 ,标志着历史人类学在中国有了良好的开端 ,扩大了人类学理论在历史学界的影响     

汉族案例：中华民族从多元走向一体

中华民族从多元走向一体是一个过程，而且是一个很长的历史过程。在这个历史过程中，民族与民族之间的分分合合、合合分分必然会形成一些阶段性的民族融合成果。其中汉民族就是一个典型的从多元走向一体的案例，从中可以窥见中华民族的未来将如何在发展中实现“多元一体”。     

Geochemistry of Sinian tillites from Hunan Province, South China--A test of the Snowball Earth hypothesis

A glaciomarine succession of Neoproterozoic age (between 748～584 Ma) is widespread on the Yangtze Platform, South China. The deposition took place during an intermediate to low paleolatitude position of the Yangtze Platform. The Snowball Earth hypothesis offers an explanation for the occurrence of low-latitude tillites in general. It is based on records obtained of deposits underlying and overlying the tillites. In contrast, we focused on the tillites themselves by using geochemistry to obtain detailed information about the conditions during the glaciation. Of particular interest are environmental conditions, which are closely related to the climate development. Additionally, stable isotope geochemistry was used for a paleoclimate interpretation. The geochemical results of the Sinian glacial succession on the Yangtze Platform are compared to the predictions made by the Snowball Earth hypothesis.     

对《雪球》“族群”理论运用的商榷

《雪球》一书在汉民族研究的方法论上有许多突破,但《雪球》在“族群”理论运用中也存在一些不足。与国内“族群”理论的研究成果相比较,该书在“族群”理论的运用上可以进行更多的借鉴。