Spreading in Social Systems: Reflections

In this final chapter, we consider the state-of-the-art for spreading in social systems and discuss the future of the field. As part of this reflection, we identify a set of key challenges ahead. The challenges include the following questions: how can we improve the quality, quantity, extent, and accessibility of datasets? How can we extract more information from limited datasets? How can we take individual cognition and decision making processes into account? How can we incorporate other complexity of the real contagion processes? Finally, how can we translate research into positive real-world impact? In the following, we provide more context for each of these open questions.Comment: 7 pages, chapter to appear in "Spreading Dynamics in Social Systems"; Eds. Sune Lehmann and Yong-Yeol Ahn, Springer Natur

Peer relations linking overweight and obesity, and mediator factors among Turkish adolescents

Depending on the individual’s body height and frame structure and body weight, obesity is considered both as a socially accepted norm in a society and as exceeding the accepted upper limits. The present study aimed to determine the associations between overweight and obesity, peer relationships, and nutritional and physical activity behaviour among Turkish adolescents. A cross-sectional study was conducted in Ankara, and the sample consisted of 402 adolescents (171 boys and 231 girls) aged between 12 and 17 years. A physical examination was conducted to collect anthropometric measurements (height, weight, BMI, and body fat using bio-impedance analysis), and detailed information was collected on adolescents’ behaviour (Peer Relationship Scale with four sub-scales of commitment, trust and identification, self-disclosure, and loyalty), diet (24h recall dietary questionnaire), physical activity, self-reported weight, parental attitudes, and socio-economic circumstances. BMI was evaluated using IOTF cut-off points, and simple mediation analyses were performed using ordinary least squares path analysis by the PROCESS macro for SPSS. The results showed that according to the weight status by BMI using IOTF cut-offs, thinness was more prominent in girls (9.5%), overweight was higher in girls (19%), while obesity was higher in boys (8.8%). Total body fat percentage was found to be higher in girls in all weight groups (p < 0.001). The Peer Relationship Scale and, commitment, self-disclosure, and loyalty sub-scales were found to be statistically significant (p < 0.001); girls tend to have higher scores except for the loyalty sub- scale. According to the results, self-reported and actual weight differences were found to be significant in both sexes (p < 0.001), and among IOTF weight groups overweight girls tended to report their weight approximately 2 kg lower than their actual weight and obese girls more than 5 kg lower. In conclusion, the mediation analysis showed that fat percentage, self-reported weight difference, and BMI were significant predictors of Peer Relationship Score where fat percentage partially mediated the relationship between the Peer Relationship Scale and BMI, and full mediation effect of self-reported weight difference was also significant. The relation of the high level of fat accumulation and overweight/obesity with Peer Relationship Scores and its sub-domains should be carefully monitored

Fashion, Cooperation, and Social Interactions

Fashion plays such a crucial rule in the evolution of culture and society that it is regarded as a second nature to the human being. Also, its impact on economy is quite nontrivial. On what is fashionable, interestingly, there are two viewpoints that are both extremely widespread but almost opposite: conformists think that what is popular is fashionable, while rebels believe that being different is the essence. Fashion color is fashionable in the first sense, and Lady Gaga in the second. We investigate a model where the population consists of the afore-mentioned two groups of people that are located on social networks (a spatial cellular automata network and small-world networks). This model captures two fundamental kinds of social interactions (coordination and anti-coordination) simultaneously, and also has its own interest to game theory: it is a hybrid model of pure competition and pure cooperation. This is true because when a conformist meets a rebel, they play the zero sum matching pennies game, which is pure competition. When two conformists (rebels) meet, they play the (anti-) coordination game, which is pure cooperation. Simulation shows that simple social interactions greatly promote cooperation: in most cases people can reach an extraordinarily high level of cooperation, through a selfish, myopic, naive, and local interacting dynamic (the best response dynamic). We find that degree of synchronization also plays a critical role, but mostly on the negative side. Four indices, namely cooperation degree, average satisfaction degree, equilibrium ratio and complete ratio, are defined and applied to measure people's cooperation levels from various angles. Phase transition, as well as emergence of many interesting geographic patterns in the cellular automata network, is also observed.Comment: 21 pages, 12 figure

Pituitary infiltration by non-Hodgkin's lymphoma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Pituitary adenomas represent the most frequently observed type of sellar masses; however, the presence of a rapidly growing sellar tumor, diabetes insipidus, ophthalmoplegia and headaches in an older patient strongly suggests metastasis to the pituitary. Since the anterior pituitary has a great reserve capacity, metastasis to the pituitary and pituitary involvement in lymphoma are usually asymptomatic. Whereas diabetes insipidus is the most frequent symptom, patients can present with headaches, ophthalmoplegia and bilateral hemianopsia.</p> <p>Case presentation</p> <p>A 70-year-old woman with no previous history of malignancy presented with headaches, right oculomotor nerve palsy and diabetes insipidus. As magnetic resonance imaging revealed a sellar mass involving the pituitary gland and infundibular stalk, which also extended into the right cavernous sinus and sphenoid sinus, the patient underwent an immediate transsphenoidal decompression surgery. Her prolactin was 102.4 ng/ml, whereas her gonadotropic hormone levels were low. A low level of urine osmolality after overnight water deprivation, along with normal plasma osmolality suggested diabetes insipidus. Histological examination revealed that the mass had been the infiltration of a high grade B-cell non-Hodgkin's lymphoma involving respiratory system epithelial cells. Paranasal sinus computed tomography scanning and magnetic resonance imaging of the thorax and abdomen were performed. Since magnetic resonance imaging did not reveal any abnormality, after paranasal sinus computed tomography was performed, we concluded that the primary lymphoma originated from the sphenoid sinus and infiltrated the pituitary. Chemotherapy and radiotherapy to the sellar area were planned, but the patient died and her family did not permit an autopsy.</p> <p>Conclusion</p> <p>Lymphoma infiltration to the pituitary is difficult to differentiate from pituitary adenoma, meningioma and other sellar lesions. To plan the treatment of lymphoma infiltration of the pituitary gland, it must be differentiated from other sellar lesions.</p

Dynamics in online social networks

An increasing number of today's social interactions occurs using online social media as communication channels. Some online social networks have become extremely popular in the last decade. They differ among themselves in the character of the service they provide to online users. For instance, Facebook can be seen mainly as a platform for keeping in touch with close friends and relatives, Twitter is used to propagate and receive news, LinkedIn facilitates the maintenance of professional contacts, Flickr gathers amateurs and professionals of photography, etc. Albeit different, all these online platforms share an ingredient that pervades all their applications. There exists an underlying social network that allows their users to keep in touch with each other and helps to engage them in common activities or interactions leading to a better fulfillment of the service's purposes. This is the reason why these platforms share a good number of functionalities, e.g., personal communication channels, broadcasted status updates, easy one-step information sharing, news feeds exposing broadcasted content, etc. As a result, online social networks are an interesting field to study an online social behavior that seems to be generic among the different online services. Since at the bottom of these services lays a network of declared relations and the basic interactions in these platforms tend to be pairwise, a natural methodology for studying these systems is provided by network science. In this chapter we describe some of the results of research studies on the structure, dynamics and social activity in online social networks. We present them in the interdisciplinary context of network science, sociological studies and computer science.Comment: 17 pages, 4 figures, book chapte

Modality-Dependent Impact of Hallucinations on Low-Frequency Fluctuations in Schizophrenia

Prior resting-state functional magnetic resonance imaging (fMRI) analyses have identified patterns of functional connectivity associated with hallucinations in schizophrenia (Sz). In this study, we performed an analysis of the mean amplitude of low-frequency fluctuations (ALFF) to compare resting state spontaneous low-frequency fluctuations in patients with Sz who report experiencing hallucinations impacting different sensory modalities. By exploring dynamics across 2 low-frequency passbands (slow-4 and slow-5), we assessed the impact of hallucination modality and frequency range on spatial ALFF variation. Drawing from a sample of Sz and healthy controls studied as part of the Functional Imaging Biomedical Informatics Research Network (FBIRN), we replicated prior findings showing that patients with Sz have decreased ALFF in the posterior brain in comparison to controls. Remarkably, we found that patients that endorsed visual hallucinations did not show this pattern of reduced ALFF in the back of the brain. These patients also had elevated ALFF in the left hippocampus in comparison to patients that endorsed auditory (but not visual) hallucinations. Moreover, left hippocampal ALFF across all the cases was related to reported hallucination severity in both the auditory and visual domains, and not overall positive symptoms. This supports the hypothesis that dynamic changes in the ALFF in the hippocampus underlie severity of hallucinations that impact different sensory modalities

Quantitative imaging of concentrated suspensions under flow

We review recent advances in imaging the flow of concentrated suspensions, focussing on the use of confocal microscopy to obtain time-resolved information on the single-particle level in these systems. After motivating the need for quantitative (confocal) imaging in suspension rheology, we briefly describe the particles, sample environments, microscopy tools and analysis algorithms needed to perform this kind of experiments. The second part of the review focusses on microscopic aspects of the flow of concentrated model hard-sphere-like suspensions, and the relation to non-linear rheological phenomena such as yielding, shear localization, wall slip and shear-induced ordering. Both Brownian and non-Brownian systems will be described. We show how quantitative imaging can improve our understanding of the connection between microscopic dynamics and bulk flow.Comment: Review on imaging hard-sphere suspensions, incl summary of methodology. Submitted for special volume 'High Solid Dispersions' ed. M. Cloitre, Vol. xx of 'Advances and Polymer Science' (Springer, Berlin, 2009); 22 pages, 16 fig