Incomplete Diversification and Asset Pricing

Investors in equilibrium are modeled as facing investor specific risks across the space of assets. Personalized asset pricing models reflect these risks. Averaging across the pool of investors we obtain a market asset pricing model that reflects market risk exposures. It is observed on invoking a law of large numbers applied to an infinite population of investors, that many personally relevant risk considerations can be eliminated from the market asset pricing model. Examples illustrating the effects of undiversified labor income and taste specific price indices are provided. Suggestions for future work on asset pricing include a need to focus on identifying and explaining investor specific risk exposures.Diversification, Asset Pricing, Investor specific risks

Cardiac Allograft Vasculopathy: Pathogenesis and Role of Coronary Computed Tomography Angiography in the Diagnosis and Surveillance

Cardiac allograft vasculopathy (CAV) is an entity unique to the cardiac transplant patients and remains the leading cause of mortality after the first year of transplantation causing chronic allograft rejection. It is an accelerated form of coronary artery disease, occurring diffusely, starting from the small distal vessels and ultimately extending to intramyocardial and epicardial vessels of the allograft. Multiple traditional metabolic risk factors known to cause atherosclerosis have been identified as a trigger for CAV. Moreover, several nontraditional environmental risk factors such as viral infections, donor’s age, underlying cardiac disease and mechanism of donor brain death have also been implicated. The pathogenesis of CAV is complex with involvement of both immunological and non-immunological mechanisms and still remains poorly understood. Clinical diagnosis of CAV is difficult as symptoms of angina are usually lacking because of denervated nature of the allograft and it is identified when the graft is already compromised. Currently, invasive testing stands as the gold standard for its diagnosis; however its utility has been questioned. Coronary CT angiography (CCTA) has emerged as a promising noninvasive tool for the diagnosis of CAV. This review discusses the risk factors, pathogenesis and diagnosis of CAV and utility of CCTA in its diagnosis and surveillance

Rapid Estimation of Fouled Railroad Ballast Mechanical Properties

Ballast fouling and ballast deterioration are significant maintenance concerns. Ballast fouling occurs because of the wearing of the ballast against the tie and other ballast, along with the intrusion of fines from the subgrade and deposition of coal dust or soil particles from the surface. In this study, the assessment of mechanical properties of fouled ballast using available geotechnical tests is discussed. These mechanical properties include subgrade reaction modulus from static plate loading tests, dynamic deformation modulus from light weight deflectometer (LWD) tests, and California bearing ratio (CBR) from dynamic cone penetrometer (DCP) tests. The test results show similar trends for these mechanical properties, which were determined by varying the fouling amount as well as the moisture content. The mechanical properties first increased with the moisture content up to a certain value and then decreased rapidly after a peak value. This article also discusses the correlations between these mechanical properties developed from the tests

A phenomenological exploration of the feedback experience of medical students after summative exam failure

Background: Preventing medical students entering cycles of underperformance following assessment is a priority due to the consequences for the student, faculty, and wider society. The benefits from feedback may be inadequately accessed by students in difficulty due to the emotional response evoked by examination failure. This study aims to explore medical students’ experiences of receiving feedback after summative assessment failure and investigate the role of emotions on motivation for learning after underperformance, to better support remediation and preparation for future assessments. Methods: This study used interpretative phenomenological analysis (IPA) to explore the experiences of four medical students who failed summative assessments. Additionally, a content analysis was conducted using Linguistic Inquiry and Word Count (LIWC) to investigate the characteristics and use of language to describe their emotional response. Results: Anger, fear, anxiety, and sadness were emotions frequently experienced after examination failure. These emotions led to feelings of mistrust of the medical school and subsequent distrust in the university’s assessment processes, impacting on the desire to engage with feedback. There was dissonance between the students' perceptions of what feedback should provide and what benefit feedback provided after summative assessments. The linguistic inquiry further confirmed an initial (and sometimes long lived) negative affective state after experiencing failure, and a barrier to engagement with remediation when not effectively managed. Conclusions: A range of emotions, directed at themselves and the medical school are experienced by students following exam failure. These emotions lead to a range of negative feelings and responses that affect how students make sense of and move on from the failure experience. There is a need for educators to better understand and support students to manage, reflect and contextualise their emotional responses, minimise external attribution and to enable focus on remediation and learning

Basic essential education program (BEEP): a brief introductory faculty development course for medical teachers

Background: Physicians have a unique role in teaching future physicians and allied health professionals. Yet, most medical doctors have limited instruction in this critical component of their daily activity. Methods: This study was a prospective cohort study of the effectiveness of a local teaching program at two teaching hospitals for junior faculty. Based on a needs analysis and literature review, the teaching program was developed in an accessible and compact format of six consecutive, one-hour "lunch and learn" sessions, held locally over a six week period. Pre-post questionnaires and focus groups were used to evaluate the program. Results: Participants reported being satisfied with the course as whole, particularly in respect to the format and location. There was an improvement in their knowledge in all content areas covered. The greatest benefits were derived from fostering a community of practice and having the opportunity to role play and simulate teaching skills. An attitudinal change towards teaching was noted. Conclusions: A brief, local faculty development program was effective in enhancing physicians’ knowledge, skills, and attitudes in teaching

Evaluation of Soil Saver Walls on Aquatic Organism Passage Through Box Culverts

Reinforced concrete box culverts are designed to provide hydraulic conveyance at peak stream discharge in a cost-effective manner; however, these structures can promote headcutting. Many state departments of transportation construct soil saver walls or similar structures on the upstream of box culverts to prevent headcutting. These walls act as a drop inlet and may hinder free movement of aquatic organisms. The potential impact on aquatic organism passage has resulted in regulatory pressure to develop alternatives or modifications to the traditional soil saver wall design. This article contains the results of an analysis of the potential impact of box culverts with solid soil saver walls on aquatic organism passage. The results of a survey of thirty states and fifteen field sites on the current state-of-practice for box culverts, and flume tests using model box culverts with a solid soil saver wall and with modified design to promote aquatic passage are presented. Modifications to the soil saver wall design are recommended based on the results of the survey of states, field surveys, and flume testing

A Stein characterisation of the generalized hyperbolic distribution

The generalized hyperbolic (GH) distributions form a five parameter family of probability distributions that includes many standard distributions as special or limiting cases, such as the generalized inverse Gaussian distribution, Student's $t$-distribution and the variance-gamma distribution, and thus the normal, gamma and Laplace distributions. In this paper, we consider the GH distribution in the context of Stein's method. In particular, we obtain a Stein characterisation of the GH distribution that leads to a Stein equation for the GH distribution. This Stein equation reduces to the Stein equations from the current literature for the aforementioned distributions that arise as limiting cases of the GH superclass.Comment: 19 pages, to appear in ESAIM: Probability and Statistics, 2017

The Sinus Venosus Veno-Venous Bridge: Not a septal defect

This review provides an update on the morphology of the sinus venosus defect. It was earlier believed that a 'common wall' separated the right pulmonary veins from the superior caval vein. In the sinus venosus defects, this wall was absent. Current evidence shows that the superior rim of the oval fossa, rather than forming a second septum or representing a common wall, is an infolding between the walls of the caval veins and the right pulmonary veins. The sinus venosus defect is caused by the anomalous connection of one or more pulmonary veins to a systemic vein. However, the pulmonary vein(s) retain their left atrial connections, leading to a veno-venous bridge that allows interatrial shunting outside the oval fossa. True atrial septal defects are located within the oval fossa or in the anteo-inferior buttress, while sinus venosus defects, ostium defects and coronary sinus defects are morphologically distinct from them. Keywords: Heart Septal Defects, Atrial; Diagnostic Imaging; Sinoatrial Node; Vena Cava, Superior

Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2ﾠfield effect transistors

We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility