Bio-inspired swing leg control for spring-mass robots running on ground with unexpected height disturbance.

We proposed three swing leg control policies for spring-mass running robots, inspired by experimental data from our recent collaborative work on ground running birds. Previous investigations suggest that animals may prioritize injury avoidance and/or efficiency as their objective function during running rather than maintaining limit-cycle stability. Therefore, in this study we targeted structural capacity (maximum leg force to avoid damage) and efficiency as the main goals for our control policies, since these objective functions are crucial to reduce motor size and structure weight. Each proposed policy controls the leg angle as a function of time during flight phase such that its objective function during the subsequent stance phase is regulated. The three objective functions that are regulated in the control policies are (i) the leg peak force, (ii) the axial impulse, and (iii) the leg actuator work. It should be noted that each control policy regulates one single objective function. Surprisingly, all three swing leg control policies result in nearly identical subsequent stance phase dynamics. This implies that the implementation of any of the proposed control policies would satisfy both goals (damage avoidance and efficiency) at once. Furthermore, all three control policies require a surprisingly simple leg angle adjustment: leg retraction with constant angular acceleration.

Cardiac manifestations of parasitic infections part 3: pericardial and miscellaneous cardiopulmonary manifestations.

This is part three of a three-part series discussing parasites of the heart. In this section, we present an overview on parasitic diseases involving predominantly the pericardium and other miscellaneous cardiopulmonary manifestations such as some pulmonary hypertension syndromes and endomyocardial fibrosis.

Cardiac manifestations of parasitic infections part 1: overview and immunopathogenesis.

Parasitic infections produce a wide spectrum of cardiac manifestations. They may involve various anatomic structures of the heart and are manifested clinically as myocarditis, cardiomyopathies, pericarditis, or pulmonary hypertension in many resource-constrained settings. However, many parasitic infections involving the heart may also be currently diagnosed in developed countries due to growing worldwide travel, blood transfusions, and increasing numbers of immunosuppression states such as organ transplantation, use of immunosuppressive agents, or HIV/AIDS. Clinicians anywhere in the globe need to be aware of the potential cardiac manifestations of parasitic diseases. This is part one of a three-part series discussing parasites of the heart. In this section, we provide a general overview and immunopathogenesis of parasitic infections of the heart.

Memories of patients with a giant left atrium.

This article emphasizes that the abnormalities noted on chest x-ray films of the chest can be diagnostic of giant left atrium. It also points out that a giant left atrium that occasionally occurs in patients with rheumatic mitral valve regurgitation does not occur in patients with mitral regurgitation due to other causes.

What I tell medical house staff about old hearts.

House officers tend to view elderly patients with heart disease in the same way they view middle-aged patients. This essay discusses the difference between old hearts and middle-aged hearts. The teaching setting, as well as the common cardiovascular problems seen in the elderly, are described in this essay. In addition, an explanation is given as to why the clinical picture of the same disease is different in elderly patients than in middle-aged patients.

Methods used to interpret the 12-lead electrocardiogram: Pattern memorization versus the use of vector concepts.

This article extols the value of using Grant's approach to the interpretation of electrocardiograms (ECGs). The essay includes a discussion on how people learn and emphasizes the difference in memorizing information, thinking, and learning. Simply stated, the brains of most people are not designed to memorize countless numbers of ECG patterns. Accordingly, the essay supports the view that a method of interpretation must be used, and the reader is encouraged to use basic principles of electrocardiography, including vector concepts, to interpret each ECG.

I view with alarm (the fall of 1999)

This article emphasizes that medical schools only introduce students to the skills, including cognitive skills, that are needed to solve and manage medical problems. These skills, including cognitive skills, should be perfected during house staff training. The teaching-attending physician is in the key position to be a true teacher. Without the help of excellent teaching-attendings, trainees may not develop proficiency in the skills, including cognitive skills, needed for the practice of medicine.

Electrocardiographic predictors of right ventricular volume measured by magnetic resonance imaging late after total repair of tetralogy of Fallot.

BACKGROUND: Right ventricular dysfunction occurs in many patients with significant pulmonary valve regurgitation late after initial total repair of tetralogy of Fallot. Methods to predict which of these patients are at increased risk of late morbidity and mortality are not yet known. HYPOTHESIS: This study evaluated electrocardiographic (ECG) predictors of severe right ventricular dilatation determined by magnetic resonance imaging (MRI) volumes in patients with tetralogy of Fallot late after initial corrective repair. METHODS: We retrospectively reviewed the ECGs and MRI right ventricular volume measurements of 20 patients (age 4.4 to 19.3 years, mean 10.0 years) with significant pulmonary valve regurgitation late after repair of tetralogy of Fallot. All patients had enlarged, hypokinetic right ventricles by echocardiography. The patients were grouped based on an indexed right ventricular end-diastolic volume (RVEDV/BSA) of < 102 ml/m2 (Group 1) or > or = 102 ml/m2 (Group 2). We determined the sensitivity, specificity, positive and negative predictive values of QRS duration, and mean frontal plane QRS axis for predicting right ventricular volumes. RESULTS: A maximal QRS duration of > or = 150 ms or a northwest quadrant frontal plane QRS axis had 85% sensitivity, 86% specificity, 92% positive predictive value, and 75% negative predictive value for predicting an RVEDV/BSA of > or = 102 ml/m2. The mean QRS duration was significantly longer in Group 2 than in Group 1 patients (156 ms vs. 125 ms, p = 0.005). CONCLUSIONS: In patients late after repair of tetralogy of Fallot with significant pulmonary valve regurgitation a maximal manually measured QRS duration of > or = 150 ms and/or a frontal plane QRS northwest quadrant axis can predict patients with marked right ventricular enlargement. The presence of either of these findings on the ECG signifies patients who require further evaluation and consideration for pulmonary valve replacement.

The use of the New York Heart Association's classification of cardiovascular disease as part of the patient's complete Problem List.

This paper extols the value of combining two systems in order to improve learning, teaching, communication, patient care, and clinical research in patients with heart disease. This is accomplished by using Weed's recommendation regarding the creation of a complete Problem List and, within this context, characterizing the cardiac or vascular problem according to the recommendations of the New York Heart Association.