Ranking Network of a Captive Rhesus Macaque Society: A Sophisticated Corporative Kingdom

We develop a three-step computing approach to explore a hierarchical ranking network for a society of captive rhesus macaques. The computed network is sufficiently informative to address the question: Is the ranking network for a rhesus macaque society more like a kingdom or a corporation? Our computations are based on a three-step approach. These steps are devised to deal with the tremendous challenges stemming from the transitivity of dominance as a necessary constraint on the ranking relations among all individual macaques, and the very high sampling heterogeneity in the behavioral conflict data. The first step simultaneously infers the ranking potentials among all network members, which requires accommodation of heterogeneous measurement error inherent in behavioral data. Our second step estimates the social rank for all individuals by minimizing the network-wide errors in the ranking potentials. The third step provides a way to compute confidence bounds for selected empirical features in the social ranking. We apply this approach to two sets of conflict data pertaining to two captive societies of adult rhesus macaques. The resultant ranking network for each society is found to be a sophisticated mixture of both a kingdom and a corporation. Also, for validation purposes, we reanalyze conflict data from twenty longhorn sheep and demonstrate that our three-step approach is capable of correctly computing a ranking network by eliminating all ranking error

Comparing the hierarchy of keywords in on-line news portals

The tagging of on-line content with informative keywords is a widespread phenomenon from scientific article repositories through blogs to on-line news portals. In most of the cases, the tags on a given item are free words chosen by the authors independently. Therefore, relations among keywords in a collection of news items is unknown. However, in most cases the topics and concepts described by these keywords are forming a latent hierarchy, with the more general topics and categories at the top, and more specialised ones at the bottom. Here we apply a recent, cooccurrence-based tag hierarchy extraction method to sets of keywords obtained from four different on-line news portals. The resulting hierarchies show substantial differences not just in the topics rendered as important (being at the top of the hierarchy) or of less interest (categorised low in the hierarchy), but also in the underlying network structure. This reveals discrepancies between the plausible keyword association frameworks in the studied news portals

Hierarchy measure for complex networks

Nature, technology and society are full of complexity arising from the intricate web of the interactions among the units of the related systems (e.g., proteins, computers, people). Consequently, one of the most successful recent approaches to capturing the fundamental features of the structure and dynamics of complex systems has been the investigation of the networks associated with the above units (nodes) together with their relations (edges). Most complex systems have an inherently hierarchical organization and, correspondingly, the networks behind them also exhibit hierarchical features. Indeed, several papers have been devoted to describing this essential aspect of networks, however, without resulting in a widely accepted, converging concept concerning the quantitative characterization of the level of their hierarchy. Here we develop an approach and propose a quantity (measure) which is simple enough to be widely applicable, reveals a number of universal features of the organization of real-world networks and, as we demonstrate, is capable of capturing the essential features of the structure and the degree of hierarchy in a complex network. The measure we introduce is based on a generalization of the m-reach centrality, which we first extend to directed/partially directed graphs. Then, we define the global reaching centrality (GRC), which is the difference between the maximum and the average value of the generalized reach centralities over the network. We investigate the behavior of the GRC considering both a synthetic model with an adjustable level of hierarchy and real networks. Results for real networks show that our hierarchy measure is related to the controllability of the given system. We also propose a visualization procedure for large complex networks that can be used to obtain an overall qualitative picture about the nature of their hierarchical structure.Comment: 29 pages, 9 figures, 4 table

Modelling Dominance Hierarchies Under Winner and Loser Effects

Animals that live in groups commonly form themselves into dominance hierarchies which are used to allocate important resources such as access to mating opportunities and food. In this paper, we develop a model of dominance hierarchy formation based upon the concept of winner and loser effects using a simulation-based model and consider the linearity of our hierarchy using existing and new statistical measures. Two models are analysed: when each individual in a group does not know the real ability of their opponents to win a fight and when they can estimate their opponents' ability every time they fight. This estimation may be accurate or fall within an error bound. For both models, we investigate if we can achieve hierarchy linearity, and if so, when it is established. We are particularly interested in the question of how many fights are necessary to establish a dominance hierarchy

Crayfish Recognize the Faces of Fight Opponents

The capacity to associate stimuli underlies many cognitive abilities, including recognition, in humans and other animals. Vertebrates process different categories of information separately and then reassemble the distilled information for unique identification, storage and recall. Invertebrates have fewer neural networks and fewer neural processing options so study of their behavior may reveal underlying mechanisms still not fully understood for any animal. Some invertebrates form complex social colonies and are capable of visual memory–bees and wasps, for example. This ability would not be predicted in species that interact in random pairs without strong social cohesion; for example, crayfish. They have chemical memory but the extent to which they remember visual features is unknown. Here we demonstrate that the crayfish Cherax destructor is capable of visual recognition of individuals. The simplicity of their interactions allowed us to examine the behavior and some characteristics of the visual features involved. We showed that facial features are learned during face-to-face fights, that highly variable cues are used, that the type of variability is important, and that the learning is context-dependent. We also tested whether it is possible to engineer false identifications and for animals to distinguish between twin opponents

Modeling Social Dominance: Elo-Ratings, Prior History, and the Intensity of Aggression

Among studies of social species, it is common practice to rank individuals using dyadic social dominance relationships. The Elo-rating method for achieving this is powerful and increasingly popular, particularly among studies of nonhuman primates, but suffers from two deficiencies that hamper its usefulness: an initial burn-in period during which the model is unreliable and an assumption that all win–loss interactions are equivalent in their influence on rank trajectories. Here, I present R code that addresses these deficiencies by incorporating two modifications to a previ- ously published function, testing this with data from a 9-mo observational study of social interactions among wild male chimpanzees (Pan troglodytes) in Uganda. I found that, unmodified, the R function failed to resolve a hierarchy, with the burn-in period spanning much of the study. Using the modified function, I incorporated both prior knowledge of dominance ranks and varying intensities of aggression. This effectively eliminated the burn-in period, generating rank trajectories that were consistent with the direction of pant-grunt vocalizations (an unambiguous demonstration of subordinacy) and field observations, as well as showing a clear relationship between rank and mating success. This function is likely to be particularly useful in studies that are short relative to the frequency of aggressive interactions, for longer-term data sets disrupted by periods of lower quality or missing data, and for projects investigating the relative importance of differing behaviors in driving changes in social dominance. This study highlights the need for caution when using Elo-ratings to model social dominance in nonhuman primates and other species

Interventional Removal of Intravascular Medical Devices: Methods and Technical Success

Purpose: Evaluation of the technical success rate and complications when retrieving dislocated intravascular foreign bodies. Material and Methods: Between 1999 and 2015 38 patients (21 female; 17 male; Age: 17 -92; Average 54.3 years) underwent an extraction of intravascular dislocated foreign bodies, which were not lost during a radiological intervention. The extracted material included 29 port catheters, 3 tips of tunneled dialysis catheters, 2 stents, 2 guide wires, 1 CVC tip and 1 AS occluder device. Various catheters for repositioning and extraction were used. The access was transarterial as well as transvenous. Technical success was defined as complete removal of the foreign body. Results: The technical success rate was 92.1 % (35 of 38). In 17 patients an additional catheter was necessary to reposition the foreign body in order to make it accessible for the extraction catheter. In one case a stent was relocated and remodeled within the patient and was not extracted. In another case we experienced a dislocation of a small fragment of the port catheter into the distal parts of the pulmonary artery, which couldn't be extracted. A guide wire could not be extracted as it was already adhered with the vessel wall. Peri-interventional complications were not documented. Conclusion: The percutaneous extraction of dislocated intravascular foreign bodies is technically successful and poor of complications. Interventional therapy can avoid surgical removal. Key points: The percutaneous extraction of dislocated intravascular foreign bodies is technically successful and safe. In most cases surgical removal can be avoided. The gooseneck-snare catheter was mainly used for the extraction of intravascular foreign bodies. Citation Format: Ayx I, Goessmann H, Hubauer H et al. Interventional Removal of Intravascular Medical Devices: Methods and Technical Success. Fortschr Rontgenstr 2016; 188: 566-57

Contrast-enhanced ultrasound with perfusion analysis in patients with venous malformations before and after percutaneous treatment with ethanol-gel

INTRODUCTION: Percutaneous sclerotherapy is a well-established treatment option for venous malformations (VM). A recently established sclerosing agent is ethanol-gel. Aim of this study was to identify, if contrast-enhanced ultrasound (CEUS) with an integrated perfusion analysis allows for differentiation between untreated VM, healthy tissue, and with gelified ethanol treated malformation tissue. MATERIAL AND METHODS: In this institutional review board approved prospective study symptomatic VM patients underwent CEUS at exactly the same position before and after sclerotherapy with ethanol-gel. Two experienced sonographers performed all examinations after the bolus injection of microbubbles using a multi-frequency probe with 6 - 9 MHz of a high-end ultrasound machine. An integrated perfusion analysis was applied in the center of the VM and in healthy, surrounding tissue. For both regions peak enhancement (peak), time to peak (TTP), area under the curve (AUC), and mean transit time (MTT) were evaluated. Wilcoxon signed rank test was executed; p-values <0.05 were regarded statistically significant. RESULTS: In 23 patients including children (mean age 25.3 years, 19 females) before treatment all identified parameters were significantly higher in the VM center compared to healthy tissue (peak: p < 0.01; TTP: p < 0.01; AUC: p < 0.01; MTT: p < 0.01). Comparing the VM center before and after treatment, TTP (p < 0.02) and MTT (p < 0.01) reduced significantly after sclerotherapy. In surrounding tissue only peak changed after treatment in comparison to pre-treatment results (p = 0.04). Comparing data in the VM center with surrounding tissue after sclerotherapy, results still differed significantly for peak (p < 0.01), TTP (p < 0.01), and AUC (p < 0.01), but assimilated for MTT (p = 0.07). CONCLUSION: All with CEUS identified parameters seem to be excellent tools for differentiating between VM and healthy tissue. TTP and MTT could distinguish between with ethanol-gel sclerotized VM portions and untreated malformation parts and thereby might assist the monitoring of sclerotherapy with ethanol-gel