Software for interpreting cardiopulmonary exercise tests

<p>Abstract</p> <p>Background</p> <p>Cardiopulmonary exercise testing (CPET) has become an important modality for the evaluation and management of patients with a diverse array of medical problems. However, interpreting these tests is often difficult and time consuming, requiring significant expertise.</p> <p>Methods</p> <p>We created a computer software program (XINT) that assists in CPET interpretation. The program uses an integrative approach as recommended in the Official Statement of the American Thoracic Society/American College of Chest Physicians (ATS/ACCP) on Cardiopulmonary Exercise Testing. In this paper we discuss the principles behind the software. We also provide the detailed logic in an accompanying file (Additional File <supplr sid="S1">1</supplr>). The actual program and the open source code are also available free over the Internet at <url>http://www.xint.org</url>. For convenience, the required download files can also be accessed from this article.</p> <suppl id="S1"> <title> <p>Additional file 1</p> </title> <text> <p>XINTlogic. This file provides the detailed logic used by the XINT program. The variable names are described in Table <tblr tid="T1">1</tblr>. The actual source code may also be read directly simply by opening the source code with a text editor.</p> </text> <file name="1471-2466-7-15-S1.doc"> <p>Click here for file</p> </file> </suppl> <p>Results</p> <p>To test the clinical usefulness of XINT, we present the computer generated interpretations of the case studies discussed in the ATS/ACCP document in another accompanying file (Additional File <supplr sid="S2">2</supplr>). We believe the interpretations are consistent with the document's criteria and the interpretations given by the expert panel.</p> <suppl id="S2"> <title> <p>Additional file 2</p> </title> <text> <p>XINTinterpretations. These are the XINT generated reports based on the five examples provided in the ATS/ACCP statement on cardiopulmonary exercise testing <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>.</p> </text> <file name="1471-2466-7-15-S2.doc"> <p>Click here for file</p> </file> </suppl> <p>Conclusion</p> <p>Computers have become an integral part of modern life. Peer-reviewed scientific journals are now able to present not just medical concepts and experimental studies, but actual functioning medical interpretive software. This has enormous potential to improve medical diagnoses and patient care. We believe XINT is such a program that will give clinically useful interpretations when used by the medical community at large.</p

Which Way Was I Going? Contextual Retrieval Supports the Disambiguation of Well Learned Overlapping Navigational Routes

Groundbreaking research in animals has demonstrated that the hippocampus contains neurons that distinguish betweenoverlapping navigational trajectories. These hippocampal neurons respond selectively to the context of specific episodes despite interference from overlapping memory representations. The present study used functional magnetic resonanceimaging in humans to examine the role of the hippocampus and related structures when participants need to retrievecontextual information to navigate well learned spatial sequences that share common elements. Participants were trained outside the scanner to navigate through 12 virtual mazes from a ground-level first-person perspective. Six of the 12 mazes shared overlapping components. Overlapping mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required the retrieval of contextual information relevant to thecurrent navigational episode. Results revealed greater activation during the successful navigation of the overlapping mazes compared with the non-overlapping mazes in regions typically associated with spatial and episodic memory, including thehippocampus, parahippocampal cortex, and orbitofrontal cortex. When combined with previous research, the current findings suggest that an anatomically integrated system including the hippocampus, parahippocampal cortex, and orbitofrontal cortexis critical for the contextually dependent retrieval of well learned overlapping navigational routes

A best choice among asset pricing models? The conditional CAPM in Australia.

We use Australian data to test the Conditional CAPM (Jagannathan and Wang, 1996). Our results are generally supportive: the model performs well compared with a number of competing asset pricing models. In contrast to Jagannathan and Wang’s study, however, we find that the inclusion of the market for human capital does not ‘save’ the concept of the time-independent market beta (it remains insignificant). We find support for the role of a “small-minus-big” factor (Fama and French, 1993) in pricing the cross-section of returns and find grounds to disagree with Jagannathan and Wang’s argument that this factor proxies for misspecified market risk

Bias and consistency of the maximum Sharpe ratio

We show that the maximum Sharpe ratio obtained via the Markowitz optimization procedure from a sample of returns on a number of risky assets is, under commonly satisfied assumptions, biased upwards for the population value. Thus investment advice, decisions and assessments based on the estimated Sharpe ratio will be overly optimistic. The bias in the estimator is shown theoretically and illustrated using a data set of Spiders and iShares. We obtain bounds on the difference between the sample maximum Sharpe ratio and its population counterpart and show that the sample estimator is consistent for the population value; thus the bias disappears asymptotically, under some reasonable assumptions. However, the bias can be significant in finite samples and persist even in very large samples. We demonstrate this with simulations based on portfolios formed from normally and t–distributed returns. As expected, the over-optimistic risk-return tradeoff predicted by the procedure is not reflected in corresponding good out-of-sample portfolio performance of the Spiders and iShares

Identity dynamics as a barrier to organizational change

This article seeks to explore the construction of group and professional identities in situations of organizational change. It considers empirical material drawn from a health demonstration project funded by the Scottish Executive Health Department, and uses insights from this project to discuss issues that arise from identity construction(s) and organizational change. In the course of the project studied here, a new organizational form was developed which involved a network arrangement with a voluntary sector organization and the employment of “lay-workers” in what had traditionally been a professional setting. Our analysis of the way actors made sense of their identities reveals that characterizations of both self and other became barriers to the change process. These identity dynamics were significant in determining the way people interpreted and responded to change within this project and which may relate to other change-oriented situations