Limit cycles in Filippov systems having a circle as switching manifold.

It is known that planar discontinuous piecewise linear differential systems separated by a straight line have no limit cycles when both linear differential systems are centers. Here, we study the limit cycles of the planar discontinuous piecewise linear differential systems separated by a circle when both linear differential systems are centers. Our main results show that such discontinuous piecewise differential systems can have zero, one, two, or three limit cycles, but no more limit cycles than three.

Cooperative UAV-UGV Autonomous Power Pylon Inspection: An Investigation of Cooperative Outdoor Vehicle Positioning Architecture.

Realizing autonomous inspection, such as that of power distribution lines, through unmanned aerial vehicle (UAV) systems is a key research domain in robotics. In particular, the use of autonomous and semi-autonomous vehicles to execute the tasks of an inspection process can enhance the efficacy and safety of the operation; however, many technical problems, such as those pertaining to the precise positioning and path following of the vehicles, robust obstacle detection, and intelligent control, must be addressed. In this study, an innovative architecture involving an unmanned aircraft vehicle (UAV) and an unmanned ground vehicle (UGV) was examined for detailed inspections of power lines.

Azygos vein lead implantation: a therapeutic option for elevated defibrillation threshold.

The evaluation of the defibrillation threshold (DFT) during the implantation of a cardioverter-defibrillator (ICD) is an important stage of the procedure, as a high DFT can be found in up to 16% of patients. We report a patient with idiopathic dilated cardiomyopathy (DCM) submitted to a biventricular ICD implantation. During the procedure, the patient showed a high DFT and showed to be resistant to usual therapeutic modalities.

Infectious endocarditis due to Streptococcus bovis in a patient with colon carcinoma.

We report the case of a 66 year-old female patient with infectious endocarditis due to Streptococcus bovis and adenocarcinoma of the colon that developed acute aortic insufficiency. She was submitted to aortic valve replacement surgery and later to tumor resection (right hemicolectomy). It is important to emphasize the need for complementing the study of the colon, even in asymptomatic individuals, when infectious endocarditis due to S.

Postpartum torsades de pointes and long QT syndrome.

This article reports the case of a puerperal patient admitted with diagnosis of urinary tract infection and heart failure. This condition evolved with torsades de pointes ventricular arrhythmias, then, hypokalemia, and use of Ciprofloxacin. Ventricular arrhythmias did not present any improvement after potassium and magnesium replacement, but after implantation of temporary pacemaker, this condition showed signs of improvement.

Myocardial revascularization surgery with regional anesthesia without an endotracheal tube in conscious patients.

Objective: To report initial experience with myocardial revascularization surgery (MRS) performed on patients who were totally awake and without an endotracheal tube.

Methods: Between January 1994 and May 2001, 272 patients underwent MRS without extracorporeal circulation. In 24, the operations were performed without the use of an endotracheal tube and with the patients totally awake and breathing normally.