Tracking urban human activity from mobile phone calling patterns.

Timings of human activities are marked by circadian clocks which in turn are entrained to different environmental signals. In an urban environment the presence of artificial lighting and various social cues tend to disrupt the natural entrainment with the sunlight. However, it is not completely understood to what extent this is the case. Here we exploit the large-scale data analysis techniques to study the mobile phone calling activity of people in large cities to infer the dynamics of urban daily rhythms. From the calling patterns of about 1,000,000 users spread over different cities but lying inside the same time-zone, we show that the onset and termination of the calling activity synchronizes with the east-west progression of the sun. We also find that the onset and termination of the calling activity of users follows a yearly dynamics, varying across seasons, and that its timings are entrained to solar midnight. Furthermore, we show that the average mid-sleep time of people living in urban areas depends on the age and gender of each cohort as a result of biological and social factors.

Admission serum lactate predicts mortality in aneurysmal subarachnoid hemorrhage.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (SAH) is the most devastating form of hemorrhagic stroke. Primary predictors of mortality are based on initial clinical presentation. Initial serum lactic acid levels have been shown to predict mortality and disease severity. Initial serum lactate may be an objective predictor or mortality. METHODS: Retrospective review of aneurysmal SAH in a large academic center over a 42-month period. Data collected included demographics, clinical data, serum, and clinical outcomes data. Epidemiologic data were collected at baseline, and patients were followed up through their inpatient stay. We compared data in the group of patients who were deceased (group A) vs survivors (group B). RESULTS: There were a total of 249 patients. Mortality was 21.5%. Mean age was the same for both groups: 57 years (group A) and 55 years (group B). Mean admission serum lactate level was 3.5 ± 2.5 (group A) and 2.2 ± 1.6 (group B; P <. 0001). The range was 0.01 to 14.7. Multivariable analysis controlling for Hunt and Hess grades showed lactic acid levels to be an independent predictor of mortality with a P value of .0018. CONCLUSIONS: In aneurysmal SAH, elevated serum lactate levels on admission may have a predictive role for mortality and represent a marker of disease severity. Currently, lactic acid levels are not ordered on all patients with SAH but perhaps should be part of the routine initial blood work and may serve as an additional prognostic marker.

Human-agent coordination in a group formation game.

Coordination and cooperation between humans and autonomous agents in cooperative games raise interesting questions on human decision making and behaviour changes. Here we report our findings from a group formation game in a small-world network of different mixes of human and agent players, aiming to achieve connected clusters of the same colour by swapping places with neighbouring players using non-overlapping information. In the experiments the human players are incentivized by rewarding to prioritize their own cluster while the model of agents' decision making is derived from our previous experiment of purely cooperative game between human players. The experiments were performed by grouping the players in three different setups to investigate the overall effect of having cooperative autonomous agents within teams. We observe that the human subjects adjust to autonomous agents by being less risk averse, while keeping the overall performance efficient by splitting the behaviour into selfish and cooperative actions performed during the rounds of the game. Moreover, results from two hybrid human-agent setups suggest that the group composition affects the evolution of clusters. Our findings indicate that in purely or lesser cooperative settings, providing more control to humans could help in maximizing the overall performance of hybrid systems.

Morningness-eveningness assessment from mobile phone communication analysis.

Human behaviour follows a 24-h rhythm and is known to be governed by the individual chronotypes. Due to the widespread use of technology in our daily lives, it is possible to record the activities of individuals through their different digital traces. In the present study we utilise a large mobile phone communication dataset containing time stamps of calls and text messages to study the circadian rhythms of anonymous users in a European country. After removing the effect of the synchronization of East-West sun progression with the calling activity, we used two closely related approaches to heuristically compute the chronotypes of the individuals in the dataset, to identify them as morning persons or "larks" and evening persons or "owls". Using the computed chronotypes we showed how the chronotype is largely dependent on age with younger cohorts being more likely to be owls than older cohorts. Moreover, our analysis showed how on average females have distinctly different chronotypes from males. Younger females are more larkish than males while older females are more owlish. Finally, we also studied the period of low calling activity for each of the users which is considered as a marker of their sleep period during the night. We found that while "extreme larks" tend to sleep more than "extreme owls" on the weekends, we do not observe much variation between them on weekdays. In addition, we have observed that women tend to sleep even less than males on weekdays while there is not much difference between them on the weekends.

Link-centric analysis of variation by demographics in mobile phone communication patterns.

We present a link-centric approach to study variation in the mobile phone communication patterns of individuals. Unlike most previous research on call detail records that focused on the variation of phone usage across individual users, we examine how the calling and texting patterns obtained from call detail records vary among pairs of users and how these patterns are affected by the nature of relationships between users. To demonstrate this link-centric perspective, we extract factors that contribute to the variation in the mobile phone communication patterns and predict demographics-related quantities for pairs of users. The time of day and the channel of communication (calls or texts) are found to explain most of the variance among pairs that frequently call each other. Furthermore, we find that this variation can be used to predict the relationship between the pairs of users, as inferred from their age and gender, as well as the age of the younger user in a pair. From the classifier performance across different age and gender groups as well as the inherent class overlap suggested by the estimate of the bounds of the Bayes error, we gain insights into the similarity and differences of communication patterns across different relationships.

Group formation on a small-world: experiment and modelling.

As a step towards studying human-agent collectives, we conduct an online game with human participants cooperating on a network. The game is presented in the context of achieving group formation through local coordination. The players set initially to a small-world network with limited information on the location of other players, coordinate their movements to arrange themselves into groups. To understand the decision-making process, we construct a data-driven model of agents based on probability matching. The model allows us to gather insight into the nature and degree of rationality employed by the human players. By varying the parameters in agent-based simulations, we are able to benchmark the human behaviour. We observe that while the players use the neighbourhood information in limited capacity, the perception of risk is optimal. We also find that for certain parameter ranges, the agents are able to act more efficiently when compared to the human players. This approach would allow us to simulate the collective dynamics in games with agents having varying strategies playing alongside human proxies.

Cost Analysis of Endovascular Coiling and Surgical Clipping for the Treatment of Ruptured Intracranial Aneurysms.

BACKGROUND: Cost-effectiveness analyses for the treatment of aneurysmal subarachnoid hemorrhage are necessary to determine health policy, treatment guidelines, and screening protocols for cerebral aneurysms. To perform these modeling studies, detailed cost data are necessary and are currently lacking. OBJECTIVE: The goal of this study was to determine detailed inpatient cost of aneurysmal subarachnoid hemorrhage. METHODS: A retrospective review of our ruptured subarachnoid hemorrhage database was performed to identify consecutive patients between January 2013 and December 2015. Patients were searched by International Classification of Disease 9 diagnosis and procedure codes. Patient demographics and clinical characteristics were acquired. The cost breakdown was compiled into a comprehensive itemized list encompassing all aspects of hospitalization. A mean cost based on resource used per patient was obtained. RESULTS: There were 269 patients treated, 209 were coiled and 60 were clipped. Mean age in the clipping group was 49 years and 55 years in the coil group (P = 0.006). Other patient demographics and clinical characteristics were found to be statistically similar for both groups. Total cost per patient for treatment and hospital stay was $74,192 for clipping and $85,553 for coiling (P = 0.06). Cost amplified with increasing Hunt and Hess grade in both clipping and coiling groups. CONCLUSIONS: The detailed cost information reported in this article can be used to help establish appropriate, standardized costs nationally by improving transparency. It can also help provide critical information necessary to develop cost-effective treatment algorithms and screening protocols.

Seasonal and geographical impact on human resting periods.

We study the influence of seasonally and geographically related daily dynamics of daylight and ambient temperature on human resting or sleeping patterns using mobile phone data of a large number of individuals. We observe two daily inactivity periods in the people's aggregated mobile phone calling patterns and infer these to represent the resting times of the population. We find that the nocturnal resting period is strongly influenced by the length of daylight, and that its seasonal variation depends on the latitude, such that for people living in two different cities separated by eight latitudinal degrees, the difference in the resting periods of people between the summer and winter in southern cities is almost twice that in the northern cities. We also observe that the duration of the afternoon resting period is influenced by the temperature, and that there is a threshold from which this influence sets in. Finally, we observe that the yearly dynamics of the afternoon and nocturnal resting periods appear to be counterbalancing each other. This also lends support to the notion that the total daily resting time of people is more or less conserved across the year.

Absence makes the heart grow fonder: social compensation when failure to interact risks weakening a relationship.

Social networks require active relationship maintenance if they are to be kept at a constant level of emotional closeness. For primates, including humans, failure to interact leads inexorably to a decline in relationship quality, and a consequent loss of the benefits that derive from individual relationships. As a result, many social species compensate for weakened relationships by investing more heavily in them. Here we study how humans behave in similar situations, using data from mobile call detail records from a European country. For the less frequent contacts between pairs of communicating individuals we observe a logarithmic dependence of the duration of the succeeding call on the time gap with the previous call. We find that such behaviour is likely when the individuals in these dyadic pairs have the same gender and are in the same age bracket as well as being geographically distant. Our results indicate that these pairs deliberately invest more time in communication so as to reinforce their social bonding and prevent their relationships decaying when these are threatened by lack of interaction. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1140/epjds/s13688-016-0097-x) contains supplementary material.

Sex differences in social focus across the life cycle in humans.

Age and gender are two important factors that play crucial roles in the way organisms allocate their social effort. In this study, we analyse a large mobile phone dataset to explore the way life history influences human sociality and the way social networks are structured. Our results indicate that these aspects of human behaviour are strongly related to age and gender such that younger individuals have more contacts and, among them, males more than females. However, the rate of decrease in the number of contacts with age differs between males and females, such that there is a reversal in the number of contacts around the late 30s. We suggest that this pattern can be attributed to the difference in reproductive investments that are made by the two sexes. We analyse the inequality in social investment patterns and suggest that the age- and gender-related differences we find reflect the constraints imposed by reproduction in a context where time (a form of social capital) is limited.

Communication with Family and Friends across the Life Course.

Each stage of the human life course is characterised by a distinctive pattern of social relations. We study how the intensity and importance of the closest social contacts vary across the life course, using a large database of mobile communication from a European country. We first determine the most likely social relationship type from these mobile phone records by relating the age and gender of the caller and recipient to the frequency, length, and direction of calls. We then show how communication patterns between parents and children, romantic partner, and friends vary across the six main stages of the adult family life course. Young adulthood is dominated by a gradual shift of call activity from parents to close friends, and then to a romantic partner, culminating in the period of early family formation during which the focus is on the romantic partner. During middle adulthood call patterns suggest a high dependence on the parents of the ego, who, presumably often provide alloparental care, while at this stage female same-gender friendship also peaks. During post-reproductive adulthood, individuals and especially women balance close social contacts among three generations. The age of grandparenthood brings the children entering adulthood and family formation into the focus, and is associated with a realignment of close social contacts especially among women, while the old age is dominated by dependence on their children.

Motor cortex stimulation for neuropathic pain syndromes: a case series experience.

Neuropathic pain is a chronic condition lacking effective management and responding poorly to standard treatment protocols. Motor cortex stimulation has emerged as a new and promising therapeutic tool with outcomes potentially affected by the specific causes and location. In this study we report a series of eight cases in the neurosurgery practice of one of the authors (R.J.B.), including neuropathic pain syndromes of trigeminal or thalamic origin with or without anesthesia dolorosa. Pain relief was evaluated on the basis of comparison of Visual Analog scores at baseline and at 3 months after surgery. In addition, we assessed differences in pain relief outcomes between cases with trigeminal neuralgia and thalamic stroke, as well as cases with or without anesthesia dolorosa (i.e. pain with numbness of the affected area). Visual Analog Scale scores showed a statistically significant decrease of 4.19 (P=0.002) at 3 months follow-up compared with baseline. Pain relief levels in four of five patients in the subgroup with facial pain were higher than 50%, and none of the patients in the subgroup with thalamic and phantom limb pain showed such a good outcome. Furthermore, we found larger pain relief levels in facial pain conditions with versus without anesthesia dolorosa. These results point to utility of motor cortex stimulation in relieving neuropathic pain, as well as better outcomes for patients with facial pain and anesthesia dolorosa. Future studies should incorporate methods to noninvasively trial those patients who may benefit from surgical implantation to predict the outcomes and maximize their negative predictive value.