Vanderbilt University

About: Vanderbilt University is a education organization based out in Nashville, Tennessee, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 45066 authors who have published 106528 publications receiving 5435039 citations. The organization is also known as: Vandy.

Helicobacter pylori: gastric cancer and beyond

Abstract: Helicobacter pyloricauses gastric adenocarcinoma in a minority of infected individuals. What have we learned about bacterial and host-specific factors that lead to malignancy, and what canH. pyloritell us about inflammatory carcinomas that develop beyond the gastric niche? Helicobacter pylori is the dominant species of the human gastric microbiome, and colonization causes a persistent inflammatory response. H. pylori-induced gastritis is the strongest singular risk factor for cancers of the stomach; however, only a small proportion of infected individuals develop malignancy. Carcinogenic risk is modified by strain-specific bacterial components, host responses and/or specific host–microbe interactions. Delineation of bacterial and host mediators that augment gastric cancer risk has profound ramifications for both physicians and biomedical researchers as such findings will not only focus the prevention approaches that target H. pylori-infected human populations at increased risk for stomach cancer but will also provide mechanistic insights into inflammatory carcinomas that develop beyond the gastric niche.

Long γ-ray bursts and core-collapse supernovae have different environments

Abstract: When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration γ-ray burst. One would then expect that these long γ-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the γ-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long γ-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration γ-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long γ-ray bursts are relatively rare in galaxies such as our own Milky Way.

Determinants of Board Size and Composition: A Theory of Corporate Boards

Abstract: This paper models the interaction of firm insiders and outsiders on a corporate board and addresses the question of the board's ideal size and composition. In the model, the board is responsible for monitoring projects and making CEO succession decisions. Inside directors are better informed regarding the quality of firm investment projects, but outsiders can use CEO succession to motivate insiders to reveal their superior information and help the board implement higher value projects. The optimal board structure is determined by the trade-off between maximizing the incentive for insiders to reveal their private information, minimizing coordination costs among outsiders and maximizing the ability of outsiders to reject inferior projects. I show that optimal board size and composition are functions of the directors' and the firm's characteristics. I also develop testable implications for cross sectional variations in the optimal board structure across firms.

Reliability Estimation in a Multilevel Confirmatory Factor Analysis Framework

Abstract: Scales with varying degrees of measurement reliability are often used in the context of multistage sampling, where variance exists at multiple levels of analysis (e.g., individual and group). Because methodological guidance on assessing and reporting reliability at multiple levels of analysis is currently lacking, we discuss the importance of examining level-specific reliability. We present a simulation study and an applied example showing different methods for estimating multilevel reliability using multilevel confirmatory factor analysis and provide supporting Mplus program code. We conclude that (a) single-level estimates will not reflect a scale's actual reliability unless reliability is identical at each level of analysis, (b) 2-level alpha and composite reliability (omega) perform relatively well in most settings, (c) estimates of maximal reliability (H) were more biased when estimated using multilevel data than either alpha or omega, and (d) small cluster size can lead to overestimates of reliability at the between level of analysis. We also show that Monte Carlo confidence intervals and Bayesian credible intervals closely reflect the sampling distribution of reliability estimates under most conditions. We discuss the estimation of credible intervals using Mplus and provide R code for computing Monte Carlo confidence intervals.

Infectious Diseases Society of America Guidelines on the Treatment and Management of Patients with COVID-19.

Abstract: Background There are many pharmacologic therapies that are being used or considered for treatment of COVID-19. There is a need for frequently updated practice guidelines on their use, based on critical evaluation of rapidly emerging literature. Objective Develop evidence-based rapid guidelines intended to support patients, clinicians and other health-care professionals in their decisions about treatment and management of patients with COVID-19. Methods IDSA formed a multidisciplinary guideline panel of infectious disease clinicians, pharmacists, and methodologists with varied areas of expertise. Process followed a rapid recommendation checklist. The panel prioritized questions and outcomes. Then a systematic review of the peer-reviewed and grey literature was conducted. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the certainty of evidence and make recommendations. Results The IDSA guideline panel agreed on 7 treatment recommendations and provided narrative summaries of other treatments undergoing evaluations. Conclusions The panel expressed the overarching goal that patients be recruited into ongoing trials, which would provide much needed evidence on the efficacy and safety of various therapies for COVID-19, given that we could not make a determination whether the benefits outweigh harms for most treatments.