Assessing Simulations of Imperial Dynamics and Conflict in the Ancient World

The development of models to capture large-scale dynamics in human history is one of the core contributions of cliodynamics. Most often, these models are assessed by their predictive capability on some macro-scale and aggregated measure and compared to manually curated historical data. In this report, we consider the model from Turchin et al. (2013), where the evaluation is done on the prediction of "imperial density": the relative frequency with which a geographical area belonged to large-scale polities over a certain time window. We implement the model and release both code and data for reproducibility. We then assess its behaviour against three historical data sets: the relative size of simulated polities vs historical ones; the spatial correlation of simulated imperial density with historical population density; the spatial correlation of simulated conflict vs historical conflict. At the global level, we show good agreement with population density ($R^2 < 0.75$), and some agreement with historical conflict in Europe ($R^2 < 0.42$). The model instead fails to reproduce the historical shape of individual polities. Finally, we tweak the model to behave greedily by having polities preferentially attacking weaker neighbours. Results significantly degrade, suggesting that random attacks are a key trait of the original model. We conclude by proposing a way forward by matching the probabilistic imperial strength from simulations to inferred networked communities from real settlement data

Modelling interdependencies between the electricity and information infrastructures

The aim of this paper is to provide qualitative models characterizing interdependencies related failures of two critical infrastructures: the electricity infrastructure and the associated information infrastructure. The interdependencies of these two infrastructures are increasing due to a growing connection of the power grid networks to the global information infrastructure, as a consequence of market deregulation and opening. These interdependencies increase the risk of failures. We focus on cascading, escalating and common-cause failures, which correspond to the main causes of failures due to interdependencies. We address failures in the electricity infrastructure, in combination with accidental failures in the information infrastructure, then we show briefly how malicious attacks in the information infrastructure can be addressed

Machine Learning in Wireless Sensor Networks: Algorithms, Strategies, and Applications

Wireless sensor networks monitor dynamic environments that change rapidly over time. This dynamic behavior is either caused by external factors or initiated by the system designers themselves. To adapt to such conditions, sensor networks often adopt machine learning techniques to eliminate the need for unnecessary redesign. Machine learning also inspires many practical solutions that maximize resource utilization and prolong the lifespan of the network. In this paper, we present an extensive literature review over the period 2002-2013 of machine learning methods that were used to address common issues in wireless sensor networks (WSNs). The advantages and disadvantages of each proposed algorithm are evaluated against the corresponding problem. We also provide a comparative guide to aid WSN designers in developing suitable machine learning solutions for their specific application challenges.Comment: Accepted for publication in IEEE Communications Surveys and Tutorial

The Long Run Impact of Bombing Vietnam

We investigate the impact of U.S. bombing on later economic development in Vietnam. The Vietnam War featured the most intense bombing campaign in military history and had massive humanitarian costs. We use a unique U.S. military dataset containing bombing intensity at the district level (N=584). We compare the heavily bombed districts to other districts controlling for baseline demographic characteristics and district geographic factors, and use an instrumental variable approach exploiting distance to the 17th parallel demilitarized zone. U.S. bombing does not have a robust negative impact on poverty rates, consumption levels, infrastructure, literacy or population density through 2002. This finding suggests that local recovery from war damage can be rapid under certain conditions, although further work is needed to establish the generality of the finding in other settings.

The Adaptive Significance of Natural Genetic Variation in the DNA Damage Response of Drosophila melanogaster.

Despite decades of work, our understanding of the distribution of fitness effects of segregating genetic variants in natural populations remains largely incomplete. One form of selection that can maintain genetic variation is spatially varying selection, such as that leading to latitudinal clines. While the introduction of population genomic approaches to understanding spatially varying selection has generated much excitement, little successful effort has been devoted to moving beyond genome scans for selection to experimental analysis of the relevant biology and the development of experimentally motivated hypotheses regarding the agents of selection; it remains an interesting question as to whether the vast majority of population genomic work will lead to satisfying biological insights. Here, motivated by population genomic results, we investigate how spatially varying selection in the genetic model system, Drosophila melanogaster, has led to genetic differences between populations in several components of the DNA damage response. UVB incidence, which is negatively correlated with latitude, is an important agent of DNA damage. We show that sensitivity of early embryos to UVB exposure is strongly correlated with latitude such that low latitude populations show much lower sensitivity to UVB. We then show that lines with lower embryo UVB sensitivity also exhibit increased capacity for repair of damaged sperm DNA by the oocyte. A comparison of the early embryo transcriptome in high and low latitude embryos provides evidence that one mechanism of adaptive DNA repair differences between populations is the greater abundance of DNA repair transcripts in the eggs of low latitude females. Finally, we use population genomic comparisons of high and low latitude samples to reveal evidence that multiple components of the DNA damage response and both coding and non-coding variation likely contribute to adaptive differences in DNA repair between populations

Sea Otter, Enhydra lutris, mortalities in California, 1968 through 1993

Sea otter, Enhydra lutris, mortality in California and the relative contribution from specific causes was assessed for the 26 years from 1968 through 1993. There were 2,082 dead sea otters recorded from Tomales Bay (Marin County) south to Bluff Cove (Los Angeles County) during that period. The average number of carcasses recorded was 80 per year and seven per month. Sex was identified in 87% (n=1,819) of the cases and was composed of 47% female and 53% male. A relative age was assigned to 97% (n=2,017) of the cases and was composed of 28% pup, 18% subadult and 54% adult. Specific causes of death were determined for 26% (n=55 1) of the cases. The majority of these (n=381) were considered to be due to natural causes and included the following specific causes: shark bitten (n=78), probably shark bitten (n=106), other natural causes (n=140), and mating wounds (n=57). The remaining (n=170) were considered to be due to human-related causes and included the following specific causes: shot (n=72), probably shot (n=8), net drowned (n=76), and other human causes (n=14). The large proportion of carcasses without an identified specific cause of death prompted a more detailed necropsy effort in 1992 and 1993. During that period, 78 of the 232 recovered carcasses were examined by veterinary pathologists and a specific cause of death was determined in 76% (n=59) of the cases. This effort identified a wide range of specific causes of death that otherwise may have been categorized as "unknown without trauma". Considering the variety of diseases diagnosed in this expanded necropsy program, it would be prudent to continue this level of examination to refine our knowledge of sea otter pathology. (48pp.