VIP: Incorporating Human Cognitive Biases in a Probabilistic Model of Retweeting

Information spread in social media depends on a number of factors, including how the site displays information, how users navigate it to find items of interest, users' tastes, and the `virality' of information, i.e., its propensity to be adopted, or retweeted, upon exposure. Probabilistic models can learn users' tastes from the history of their item adoptions and recommend new items to users. However, current models ignore cognitive biases that are known to affect behavior. Specifically, people pay more attention to items at the top of a list than those in lower positions. As a consequence, items near the top of a user's social media stream have higher visibility, and are more likely to be seen and adopted, than those appearing below. Another bias is due to the item's fitness: some items have a high propensity to spread upon exposure regardless of the interests of adopting users. We propose a probabilistic model that incorporates human cognitive biases and personal relevance in the generative model of information spread. We use the model to predict how messages containing URLs spread on Twitter. Our work shows that models of user behavior that account for cognitive factors can better describe and predict user behavior in social media.Comment: SBP 201

Uncertainties of size measurements in electron microscopy characterization of nanomaterials in foods

Electron microscopy is a recognized standard tool for nanomaterial characterization, and recommended by the European Food Safety Authority for the size measurement of nanomaterials in food. Despite this, little data have been published assessing the reliability of the method, especially for size measurement of nanomaterials characterized by a broad size distribution and/or added to food matrices. This study is a thorough investigation of the measurement uncertainty when applying electron microscopy for size measurement of engineered nanomaterials in foods. Our results show that the number of measured particles was only a minor source of measurement uncertainty for nanomaterials in food, compared to the combined influence of sampling, sample preparation prior to imaging and the image analysis. The main conclusion is that to improve the measurement reliability, care should be taken to consider replications and matrix removal prior to sample preparation

Long-Term Structural Price Relationships in Real Estate Markets

This study investigates the long-run stochastic properties of real estate assets by geographical breakdown. We also study their linkages with financial assets. The initial tests find that almost all property types exhibit the presence of nonstationarity. Thus, cointegrated methodologies are used. Structural breakpoints identified in the literature are used as a guide to divide the data into two windows, 1983-1989 and 1990-1996. The results show that real estate in the different regions exhibit a closer relationship with each other in the second period, compared with the first. Also, strong linkages between real estate regions and financial assets are noted in the second period. The South is the only region to exhibit segmentation in both periods. Overall, the information derived from our analysis sheds light on linkages among real estate assets and between real estate and financial assets and also provides a framework for creating diversified portfolios.

Moving forward in GME reform: a 4 + 1 model of resident ambulatory training

Traditional ambulatory training models have limitations in important domains, including opportunities for residents to learn, fragmentation of care delivery experience, and satisfaction with ambulatory experiences. New models of ambulatory training are needed. To compare the impact of a traditional ambulatory training model with a templated 4 + 1 model. A large university-based internal medicine residency using three different training sites: a patient-centered medical home, a hospital-based ambulatory clinic, and community private practices. Residents, faculty, and administrative staff. Development of a templated 4 + 1 model of residency where trainees do not attend to inpatient and outpatient responsibilities simultaneously. A mixed-methods analysis of survey and nominal group data measuring three primary outcomes: 1) Perception of learning opportunities and quality of faculty teaching; 2) Reported fragmentation of care delivery experience; 3) Satisfaction with ambulatory experiences. Self-reported empanelment was a secondary outcome. Residents\u27 learning opportunities increased (p = 0.007) but quality of faculty teaching was unchanged. Participants reported less fragmentation in the care residents provide patients in the inpatient and outpatient setting (p \u3c 0.0001). Satisfaction with ambulatory training improved (p \u3c 0.0001). Self-reported empanelment also increased (p \u3c 0.0001). Results held true for residents, faculty, and staff at all three ambulatory training sites (p \u3c 0.0001). A 4 + 1 model increased resident time in ambulatory continuity clinic, enhanced learning opportunities, reduced fragmentation of care residents provide, and improved satisfaction with ambulatory experiences. More studies of similar models are needed to evaluate effects on additional trainee and patient outcomes. (C) Society of General Internal Medicine 201

Impact on house staff evaluation scores when changing from a Dreyfus- to a Milestone-based evaluation model: one internal medicine residency program\u27s findings

Purpose: As graduate medical education (GME) moves into the Next Accreditation System (NAS), programs must take a critical look at their current models of evaluation and assess how well they align with reporting outcomes. Our objective was to assess the impact on house staff evaluation scores when transitioning from a Dreyfus-based model of evaluation to a Milestone-based model of evaluation. Milestones are a key component of the NAS. Method: We analyzed all end of rotation evaluations of house staff completed by faculty for academic years 2010-2011 (pre-Dreyfus model) and 2011-2012 (post-Milestone model) in one large university-based internal medicine residency training program. Main measures included change in PGY-level average score; slope, range, and separation of average scores across all six Accreditation Council for Graduate Medical Education (ACGME) competencies. Results: Transitioning from a Dreyfus-based model to a Milestone-based model resulted in a larger separation in the scores between our three post-graduate year classes, a steeper progression of scores in the PGY-1 class, a wider use of the 5-point scale on our global end of rotation evaluation form, and a downward shift in the PGY-1 scores and an upward shift in the PGY-3 scores. Conclusions: For faculty trained in both models of assessment, the Milestone-based model had greater discriminatory ability as evidenced by the larger separation in the scores for all the classes, in particular the PGY-1 class

Evidence based treatment for unstable slipped upper femoral epiphysis : systematic review and exploratory patient level analysis

The management of slipped upper femoral epiphysis is controversial and evolving as insight into the condition develops. Loder introduced the concept of slip stability and demonstrated a strong association between poor outcome and instability. Almost half of patients with unstable slip developed femoral head osteonecrosis. This has been influential in surgeons' choice of treatments. Some surgeons have adopted a minimal intervention approach such as pinning in situ or gentle reduction and pinning whereas others advocated an urgent open reduction and stabilisation of slip using various surgical techniques. In this review we analysed the influence of various interventions, timing of surgery and severity of the slip on the outcome of unstable slip

The Impact Of Insider Trading On Market Liquidity In The NASDAQ Market

This study examines the relationship between insider trading and market liquidity (spread and depth) of NASDAQ-100 stocks. Tests on an intraday sample of sell trades show no evidence of cross-sectional association between the width of the spread and insider trading, but detect some widening of the spread after the fact. Overall, our results provide mixed evidence on the ability of NASDAQ dealers to unravel informed order flow and adjust spreads accordingly. Their short-term behavior suggests an inability to detect insider trading and widen spreads, but their behavior over time suggests that dealers may attempt to recover what they apparently lose at a given point and time

The Impact Of Insider Trading On Market Liquidity In The NASDAQ Market

This study examines the relationship between insider trading and market liquidity (spread and depth) of NASDAQ-100 stocks.  Tests on an intraday sample of sell trades show no evidence of cross-sectional association between the width of the spread and insider trading, but detect some widening of the spread after the fact.  Overall, our results provide mixed evidence on the ability of NASDAQ dealers to unravel informed order flow and adjust spreads accordingly.  Their short-term behavior suggests an inability to detect insider trading and widen spreads, but their behavior over time suggests that dealers may attempt to recover what they apparently lose at a given point and time

Perioperative Teaching and Feedback: How are we doing in Canadian OTL-HNS programs?

Background: Discrepancies between resident and faculty perceptions regarding optimal teaching and feedback during surgery are well known but these differences have not yet been described in Otolaryngology - Head and Neck Surgery (OTL-HNS). The objectives were thus to compare faculty and resident perceptions of perioperative teaching and feedback in OTL-HNS residency programs across Canada with the aim of highlighting potential areas for improvement. Methods: An anonymous electronic questionnaire was distributed to residents and teaching faculty in OTL-HNS across Canada with additional paper copies distributed at four institutions. Surveys consisted of ratings on a 5-point Likert scale and open-ended questions. Responses among groups were analysed with the Wilcoxon-Mann Whitney test, while thematic analysis was used for the open-ended questions. Results: A total of 143 teaching faculty and residents responded with statistically significant differences on 11 out of 25 variables. Namely, faculty reported higher rates of pre and intra-operative teaching compared to resident reports. Faculty also felt they gave adequate feedback on residents\u27 strengths and technical skills contrary to what the residents thought. Both groups did agree however that pre-operative discussion is not consistently done, nor is feedback consistently given or sought. Conclusion: Faculty and residents in OTL-HNS residency programs disagree on the frequency and optimal timing of peri-operative teaching and feedback. This difference in perception emphasizes the need for a more structured approach to feedback delivery including explicitly stating when feedback is being given, and the overall need for better communication between residents and staff