Comparing Means under Heteroscedasticity and Nonnormality: Further Exploring Robust Means Modeling

Comparing the means of independent groups is a concern when the assumptions of normality and variance homogeneity are violated. Robust means modeling (RMM) was proposed as an alternative to ANOVA-type procedures when the assumptions of normality and variance homogeneity are violated. The purpose of this study is to compare the Type I error and power rates of RMM to the trimmed Welch procedure. A Monte Carlo study was used to investigate RMM and the trimmed Welch procedure under several conditions of nonnormality and variance heterogeneity. The results suggest that the trimmed Welch provides a better balance of Type I error control and power than RMM

Quantum Mass and Central Charge of Supersymmetric Monopoles - Anomalies, current renormalization, and surface terms

We calculate the one-loop quantum corrections to the mass and central charge of N=2 and N=4 supersymmetric monopoles in 3+1 dimensions. The corrections to the N=2 central charge are finite and due to an anomaly in the conformal central charge current, but they cancel for the N=4 monopole. For the quantum corrections to the mass we start with the integral over the expectation value of the Hamiltonian density, which we show to consist of a bulk contribution which is given by the familiar sum over zero-point energies, as well as surface terms which contribute nontrivially in the monopole sector. The bulk contribution is evaluated through index theorems and found to be nonvanishing only in the N=2 case. The contributions from the surface terms in the Hamiltonian are cancelled by infinite composite operator counterterms in the N=4 case, forming a multiplet of improvement terms. These counterterms are also needed for the renormalization of the central charge. However, in the N=2 case they cancel, and both the improved and the unimproved current multiplet are finite.Comment: 1+40 pages, JHEP style. v2: small corrections and additions, references adde

New and improved demonstrations, each illustrating a single scientific paper

Thesis (Ed.M.)--Boston Universit

Comparison of three techniques for paravertebral brachial plexus blockade in dogs

OBJECTIVE To compare success and complication rates, based on staining of nerves and other structures, among three techniques of paravertebral brachial plexus blockade (PBPB) in dogs. STUDY DESIGN Prospective randomized design. ANIMALS A total of 68 thoracic limbs from 34 dogs. METHODS Limbs were randomly assigned to blind (BL) (n=24), nerve stimulator-guided (NS) (n=21), or ultrasound-guided (US) (n=23) technique. Injections were made with 0.3 mL kg-1 of lidocaine mixed with new methylene blue. Time to perform each block and Current used during NS technique were recorded. Dogs were anesthetized during the blocks and euthanized once completed. Dissections were performed to evaluate staining of nerves, spinal cord, mediastinum, pleura and vessels. An ANOVA and Tukey adjustment for time, logistic regression for association between current and nerve staining and generalized linear mixed model for staining of different structures were used. Significance was considered when p ≤0.05. RESULTS The median (range) number of nerves stained was 2 (0-4) with BL, 1 (0.3) with NS and 1 (0.4) with US guided technique. No significant differences in straining of C6, C8 and T1 or other structures were found among techniques. Nerve C7 was more likely to be stained by BL (p=0.05). Time to perform the blocks was significantly different among techniques, with mean ± CD duration in minutes of 3.6 ± 1.8 with BL, 6.3 ± 2.7 with US and 12.2 ± 5 with NS. The most common complication was staining of the spinal cord (29%, 38% and 39% with BL, NS and US, respectively).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1467-2995/mn201

Longitudinal Effects of Embryonic Exposure to Cocaine on Morphology, Cardiovascular Physiology, and Behavior in Zebrafish

A sizeable portion of the societal drain from cocaine abuse results from the complications of in utero drug exposure. Because of challenges in using humans and mammalian model organisms as test subjects, much debate remains about the impact of in utero cocaine exposure. Zebrafish offer a number of advantages as a model in longitudinal toxicology studies and are quite sensitive physiologically and behaviorally to cocaine. In this study, we have used zebrafish to model the effects of embryonic pre-exposure to cocaine on development and on subsequent cardiovascular physiology and cocaine-induced conditioned place preference (CPP) in longitudinal adults. Larval fish showed a progressive decrease in telencephalic size with increased doses of cocaine. These treated larvae also showed a dose dependent response in heart rate that persisted 24 h after drug cessation. Embryonic cocaine exposure had little effect on overall health of longitudinal adults, but subtle changes in cardiovascular physiology were seen including decreased sensitivity to isoproterenol and increased sensitivity to cocaine. These longitudinal adult fish also showed an embryonic dose-dependent change in CPP behavior, suggesting an increased sensitivity. These studies clearly show that pre-exposure during embryonic development affects subsequent cocaine sensitivity in longitudinal adults

Using Cluster Analysis of Cytokines to Identify Patterns of Inflammation in Hospitalized Patients with Community-acquired Pneumonia:A Pilot Study

Purpose: Patients with severe community-acquired pneumonia (CAP) are believed to have an exaggerated inflammatory response to bacterial infection. Therapies aiming to modulate the inflammatory response have been largely unsuccessful, perhaps reflecting that CAP is a heterogeneous disorder that cannot be modulated by a single anti-inflammatory approach. We hypothesize that the host inflammatory response to pneumonia may be characterized by distinct cytokine patterns, which can be harnessed for personalized therapies. Methods: Here, we use hierarchical cluster analysis of cytokines to examine if patterns of inflammatory response in 13 hospitalized patients with CAP can be defined. This was a secondary data analysis of the Community-Acquired Pneumonia Inflammatory Study Group (CAPISG) database. The following cytokines were measured in plasma and sputum on the day of admission: interleukin (IL)-1β, IL-1 receptor antagonist (IL-1ra), IL-6, CXCL8 (IL-8), IL-10, IL-12p40, IL-17, interferon (IFN)γ, tumor necrosis factor (TNF)α, and CXCL10 (IP-10). Hierarchical agglomerative clustering algorithms were used to evaluate clusters of patients within plasma and sputum cytokine determinations. Results: A total of thirteen patients were included in this pilot study. Cluster analysis identified distinct inflammatory response patterns of cytokines in the plasma, sputum, and the ratio of plasma to sputum. Conclusions: Inflammatory response patterns in plasma and sputum can be identified in hospitalized patients with CAP. Characterization of the local and systemic inflammatory response may help to better discriminate patients for enrollment into clinical trials of immunomodulatory therapies

Clinician attitudes to using low dose radiotherapy to treat COVID-19 lung disease

Introduction: Current treatments for COVID-19 lung disease have limited efficacy. Low dose radiotherapy (LDRT) has received both interest and criticism as a potential treatment for this condition. In this qualitative study we explored clinicians’ perspectives in order to identify barriers to testing LDRT in clinical trials and implementing it in clinical practice. Methods: Semi-structured interviews were undertaken with six clinicians from three medical disciplines. Interviews were recorded, transcribed verbatim and analysed thematically, using a framework approach. Common themes regarding barriers to using LDRT for COVID-19 lung disease were identified from the data. Results: Three categories of barriers emerged: i) the potential to do harm to the patient, including difficulty in predicting harm and lack of existing data to inform quantification of risks; ii) the feasibility of trialling this novel treatment strategy in the clinical setting, in particular patient selection and buy-in from relevant clinician groups; and iii) the logistics of delivering the treatment, in particular risks of transmission to other patients and resources required for patient transfer. Conclusions: This study identified several barriers that may impede the evaluation and subsequent implementation of LDRT as a treatment for COVID-19 lung disease, from the perspectives of clinicians in three relevant specialties. By documenting and articulating these concerns, we hope to enhance discussion of why these barriers exist, and enable them to be addressed in a proactive manner in order to facilitate research into the potential benefits of radiation treatment for patients with COVID-19 lung disease

Cohort Profile:Scottish Diabetes Research Network Type 1 Bioresource Study (SDRNT1BIO)

No abstract available

A Review of the N-bound and the Maximal Mass Conjectures Using NUT-Charged dS Spacetimes

The proposed dS/CFT correspondence remains an intriguing paradigm in the context of string theory. Recently it has motivated two interesting conjectures: the entropic N-bound and the maximal mass conjecture. The former states that there is an upper bound to the entropy in asymptotically de Sitter spacetimes, given by the entropy of pure de Sitter space. The latter states that any asymptotically de Sitter spacetime cannot have a mass larger than the pure de Sitter case without inducing a cosmological singularity. Here we review the status of these conjectures and demonstrate their limitation. We first describe a generalization of gravitational thermodynamics to asymptotically de Sitter spacetimes, and show how to compute conserved quantities and gravitational entropy using this formalism. From this we proceed to a discussion of the N-bound and maximal mass conjectures. We then illustrate that these conjectures are not satisfied for certain asymptotically de Sitter spacetimes with NUT charge. We close with a presentation of explicit examples in various spacetime dimensionalities.Comment: 49 pages, 17 figures, a few typos corrected, addendum added with regard to some references that were later brought to our attentio

Publication bias in gastroenterological research – a retrospective cohort study based on abstracts submitted to a scientific meeting

BACKGROUND: The aim of this study was to examine the determinants of publication and whether publication bias occurred in gastroenterological research. METHODS: A random sample of abstracts submitted to DDW, the major GI meeting (1992–1995) was evaluated. The publication status was determined by database searches, complemented by a mailed survey to abstract authors. Determinants of publication were examined by Cox proportional hazards model and multiple logistic regression. RESULTS: The sample included abstracts on 326 controlled clinical trials (CCT), 336 other clinical research reports (OCR), and 174 basic science studies (BSS). 392 abstracts (47%) were published as full papers. Acceptance for presentation at the meeting was a strong predictor of subsequent publication for all research types (overall, 54% vs. 34%, OR 2.3, 95% CI 1.7 to 3.1). In the multivariate analysis, multi-center status was found to predict publication (OR 2.8, 95% CI 1.6–4.9). There was no significant association between direction of study results and subsequent publication. Studies were less likely to be published in high impact journals if the results were not statistically significant (OR 0.5, 95 CI 95% 0.3–0.6). The author survey identified lack of time or interest as the main reason for failure to publish. CONCLUSIONS: Abstracts which were selected for presentation at the DDW are more likely to be followed by full publications. The statistical significance of the study results was not found to be a predictor of publication but influences the chances for high impact publication