2,760 research outputs found

    Time as a limited resource: Communication Strategy in Mobile Phone Networks

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    We used a large database of 9 billion calls from 20 million mobile users to examine the relationships between aggregated time spent on the phone, personal network size, tie strength and the way in which users distributed their limited time across their network (disparity). Compared to those with smaller networks, those with large networks did not devote proportionally more time to communication and had on average weaker ties (as measured by time spent communicating). Further, there were not substantially different levels of disparity between individuals, in that mobile users tend to distribute their time very unevenly across their network, with a large proportion of calls going to a small number of individuals. Together, these results suggest that there are time constraints which limit tie strength in large personal networks, and that even high levels of mobile communication do not fundamentally alter the disparity of time allocation across networks.Comment: 10 pages, 3 figures. Accepted for publication in Social Network

    Treatment of bleeding in patients with liver disease

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    Patients with cirrhosis frequently have complex alterations in their hemostatic system. Although routine diagnostic tests of hemostasis in cirrhosis (platelet count, prothrombin time, fibrinogen level) are suggestive of a bleeding tendency, it is now widely accepted that these tests do not reflect hemostatic competence in this population. Rather, patients with cirrhosis appear to have a rebalanced hemostatic system with hypercoagulable elements. Therefore, routine correction of hemostasis laboratory values, for example by fresh frozen plasma or platelet concentrates, with the aim to avoid spontaneous or procedure-related bleeding is not indicated as is outlined in recent clinical guidance documents. However, little guidance on how to manage patients with cirrhosis that are actively bleeding is available. Here we present three common bleeding scenarios, variceal bleeding, post-procedural bleeding and bleeding in a critically ill cirrhosis patient, with specific management suggestions. As patients with cirrhosis generally have adequate hemostatic competence and as bleeding complications may be unrelated to hemostatic failure, prohemostatic therapy is not the first line of management in bleeding patients with cirrhosis, even in the presence of markedly abnormal platelet counts and/or prothrombin times. We provide a rationale for the restrictive approach to prohemostatic therapy in bleeding patients with cirrhosis

    Compact Radio Sources within 30" of Sgr A*: Proper Motions, Stellar Winds and the Accretion Rate onto Sgr A*

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    Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR counterparts, as well as 44 proplyd candidates within 30" of Sgr A*. Radio observations obtained in 2011 and 2014 have been used to derive proper motions of eight young stars near Sgr A*. The accuracy of proper motion estimates based on near-IR observations by Lu et al. and Paumard et al. have been investigated by using their proper motions to predict the 2014 epoch positions of near-IR stars and comparing the predicted positions with those of radio counterparts in the 2014 radio observations. Predicted positions from Lu et al. show an rms scatter of 6 mas relative to the radio positions, while those from Paumard et al. show rms residuals of 20 mas, which is mainly due to uncertainties in the IR-based proper motions. Under the assumption of homogeneous ionized winds, we also determine the mass-loss rates of 11 radio stars, finding rates that are on average \sim2 times smaller than those determined from model atmosphere calculations and near-IR data. Clumpiness of ionized winds would reduce the mass loss rate of WR and O stars by additional factors of 3 and 10, respectively. One important implication of this is a reduction in the expected mass accretion rate onto Sgr A* from stellar winds by nearly an order of magnitude to a value of few×107\times10^{-7} \msol\ yr1^{-1}. Finally, we present the positions of 318 compact 34.5 GHz radio sources within 30\arcs\ of Sgr A*. At least 45 of these have stellar counterparts in the near-IR KsK_s (2.18 μ\mum) and LL' (3.8μ\mum) bands.Comment: 30 pages, 4 figures, ApJ (in press

    Online Health Information Seeking Behaviors and Infant Feeding Practices: A Social Cognitive Theory Perspective

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    Breastfeeding benefits infants, but support is often needed to meet breastfeeding goals. Social media may help disseminate infant feeding information to caregivers. The relationship between parents’ health information-seeking behaviors (HISB) on social media and infant feeding practices remains understudied. Based on social cognitive theory (SCT), parents’ self-efficacy and outcome expectations are two potential factors for improving online HISB. We aimed to use SCT to describe associations between outcome expectations, self-efficacy (eHealth literacy), and online HISB across infant feeding groups among a nationally representative sample of U.S. parents. Eligible participants (N = 580) completed a cross-sectional online survey assessing infant feeding practices (never breastfed, only pumped, only fed-at-the-breast, and both pumped and fed-at-the-breast), self-efficacy (using eHealth literacy as a proxy), outcome expectations in online HISB, parents’ online HISB on social media, and demographic information. Survey weighted linear and logistic regression models were constructed. No online activities differed by infant feeding practices. Parents who pumped only had significantly lower eHealth literacy than parents who never breastfed (adjusted β = -2.63, 95% CI: -4.73, -0.53). Parents who used both methods had 1.78 times greater odds of considering online tools useful for making health-related decisions (95% CI: 0.96, 3.28) and 1.49 times greater odds of considering online tools important for accessing health information (95% Cl: 0.70, 3.15) than parents who never breastfed, though neither association was statistically significant. Understanding these associations between infant feeding practices and online HISB, as well as the two potential factors of parents’ self-efficacy and outcome expectations, may offer implications for tailoring online social media resources to promote breastfeeding outcomes

    Multistage Optimization of a Petroleum Production System with Material Balance Model

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    In this paper, we propose a mathematical formulation for the management of an oil production network as a multistage optimization problem. The reservoir is modeled as a controlled dynamical system by using material balance equations. We use a dynamic programming algorithm to solve the optimization problem. Two numerical applications illustrate our work: the first one consists in optimizing the production of a gas reservoir, whereas the second one tackles an oil reservoir with water injection

    The concept of rebalanced hemostasis in patients with liver disease:Communication from the ISTH SSC working group on hemostatic management of patients with liver disease

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    Patients with liver diseases acquire complex alterations in their hemostatic system that may lead to abnormalities in routine diagnostic test of hemostasis. Thrombocytopenia, prolongations in the prothrombin time and activated partial thromboplastin time, and decreased plasma fibrinogen are common in patients with advanced liver disease. Historically, liver diseases therefore have been classified as an acquired bleeding disorder. Laboratory and clinical observations have demonstrated that although routine diagnostic tests of hemostasis suggest a hypocoagulable state, patients with liver disease also tend to develop thrombotic events. Overall, patients have commensurate changes in both pro- and antihemostatic pathways. This new hemostatic balance, however, appears much more fragile than the hemostatic balance in individuals with normal liver function, and patients with liver disease can readily experience both hemostasis-related bleeding and thrombotic events. These insights into the hemostatic balance in patients with liver disease have led to revised recommendations for clinical management of hemostasis. In 2020, an SSC working group within the ISTH has been founded with the aim to disseminate new concepts on prevention and treatment of bleeding and thrombosis in patients with liver disease. The current document will outline the hemostatic changes in patients with liver disease, the limitations of routine diagnostic tests of hemostasis, and the concept of rebalanced hemostasis

    Using social media to disseminate injury prevention content: Is a picture worth a thousand words?

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    Social media (SM) offers an opportunity for injury professionals to disseminate reliable safety recommendations to parents, yet little is known about the reach and impact of SM messages on parental safety knowledge and safety behavior adoption. It is also unclear whether electronic health (eHealth) literacy level is associated with understanding of messages. Parents of children (\u3c 7 years) were recruited from a nationally representative consumer panel to complete an online survey assessing their Internet and SM usage and eHealth literacy level using the eHealth Literacy Scale (eHEALS). Participants were shown three safety SM posts where images and text matched or did not match. A post-exposure survey captured participant understanding of SM post message. Five-hundred eighty parents completed the survey. A majority of participants were female (58.6%) with high eHealth literacy (84.5%). Compared to low eHealth literate parents, a larger proportion of high eHealth literate parents correctly identified the message in mismatched posts (safe sleep: p = .0081; poison prevention: p = .0052), while similar proportions of parents with high and low eHealth literacy correctly identified a matched post for bike safety (p = .7022). Within each eHealth literacy level, high eHealth literate parents were more often able to correctly identify SM post messaging when the photo and text matched. Parents are using SM to acquire safety, health, and parenting information; therefore, it is incumbent upon disseminators to create content with clear messages. SM posts should utilize matching text with imagery that illustrates the recommended safety behavior to facilitate parental understanding of safety recommendations, regardless of audience eHealth literacy level
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