Random Trochoidal Images

Interesting images are generated by combining several randomly-generated randomly-colored trochoids. A simple code that generates these images is given

Modeling and Control of 5DOF Robot Arm Using Supervisory Control

Modeling and control of 5 degree of freedom (DOF) robot arm is the subject of this thesis. The modeling problem is necessary before applying control techniques to guarantee the execution of any task according to a desired input with minimum error. Deriving both forward and inverse kinematics is an important step in robot modeling based on Denavit Hartenberg (DH) representation. The main objective of this thesis is to control a robot arm using three controllers to acquire the desired position. Proportional integral derivative (PID) controller is used as a reference benchmark to compare its results with fuzzy logic controller (FLC) and fuzzy supervisory controller (FSC) results. FLC is applied as a second controller because of the nonlinearity in the robot manipulators. We compare the result of the PID controller and FLC results in terms of time response specifications. FSC is a hybrid between the previous two controllers. The FSC is used for tuning PID gains since PID alone performs not satisfactory in nonlinear systems. Hence, comparison of tuning of PID parameters is utilized using classical method and FSC method. Based on simulation results, FLC gives better results than classical PID controller in terms of time response and FSC is better than classical methods such as Ziegler-Nichols (ZN) in tuning PID parameters in terms of time response

Severe dehydration among cholera patients in Yemen: a cohort profile

Introduction: Cholera, an acute diarrheal illness caused by ingestion of food or water contaminated with Vibrio cholerae, is one of the major causes of morbidity and mortality globally. The occurrence of outbreaks of cholera are difficult to prevent in low and middle-income countries, especially those under armed conflicts. Methods: This study aimed to describe the characteristics of a cohort of inpatients with cholera in two main hospitals in Taiz and Sana’a, Yemen, between 3rd February 2017 and 8th December 2017. Patient data were entered into an excel database and analyzed using STATA 16.1. Descriptive summaries of patient’s data were presented as frequencies and percentages. Patients’ demographic and clinical characteristics were compared using the Chi-square test. Results: Preliminary findings from 172 hospitalizations for cholera during the study period include 163 that were severely dehydrated (94.8%). Age, education, hand hygiene, sanitation, water source, stool content and malnutrition were significantly associated with severe dehydration. Conclusions: This data contributes to a greater understanding of the associated risk factors for the occurrence of the infectious disease in the study region. Future study will analyze the risks for severe dehydration and diarrhea, and the associated healthcare costs

Antegrade axillary arterial perfusion in 3D endoscopic minimally-invasive mitral valve surgery

Background Minimally-invasive (MIS) mitral valve (MV) surgery has become standard therapy in many cardiac surgery centers. While femoral arterial perfusion is the preferred cannulation strategy in MIS mitral valve surgery, retrograde arterial perfusion is known to be associated with an increased risk for cerebral atheroembolism, particularly in atherosclerosis patients. Therefore, antegrade perfusion may be beneficial in such cases. This analysis aimed to compare outcomes of antegrade axillary vs. retrograde femoral perfusion in the MIS mitral valve surgery. Methods This analysis includes 50 consecutive patients who underwent MIS between 2016 and 2020 using arterial cannulation of right axillary artery (Group A) due to severe aortic arteriosclerosis. Perioperative outcomes of the study group were compared with a historical control group of retrograde femoral perfusion (Group F) which was adjusted for age and gender (n = 50). Primary endpoint of the study was in-hospital mortality and perioperative cerebrovascular events. Results Patients in group A had a significantly higher perioperative risk as compared to Group F (EuroSCORE II: 3.9 ± 2.5 vs. 1.6 ± 1.5; p = 0.001; STS-Score: 2.1 ± 1.4 vs. 1.3 ± 0.6; p = 0.023). Cardiopulmonary bypass time (group A: 172 ± 46; group F: 178 ± 51 min; p = 0.627) and duration of surgery (group A: 260 ± 65; group F: 257 ± 69 min; p = 0.870) were similar. However, aortic cross clamp time was significantly shorter in group A as compared to group F (86 ± 20 vs. 111 ± 29 min, p < 0.001). There was no perioperative stroke in either groups. In-hospital mortality was similar in both groups (group A: 1 patient; group F: 0 patients; p = 0.289). In group A, one patient required central aortic repair due to intraoperative aortic dissection. No further cardiovascular events occurred in Group A patients. Conclusion Selective use of antegrade axillary artery perfusion in patients with systemic atherosclerosis shows similar in-hospital outcomes as compared to lower risk patients undergoing retrograde femoral perfusion. Patients with higher perioperative risk and severe atherosclerosis can be safely treated via the minimally invasive approach with antegrade axillary perfusion

Minimal access median sternotomy for aortic valve replacement in elderly patients

BACKGROUND: We report our clinical experience with a approach for aortic valve replacement (AVR) via minimal access skin incision and complete median sternotomy. This approach was used in patients with higher age and multiple co-morbidities, facilitating an easy access with short bypass and cross clamp times. It was especially performed in patients asking for an excellent cosmetic result, who did not qualifying for minimally-invasive AVR via partial upper sternotomy. METHODS: AVR via minimal-access median sternotomy, was performed in 58 patients between 01/2009 and 11/2011. Intra- and postoperative data including cross clamp time, cardiopulmonary bypass time, mortality, stroke, pacemaker implantation, re-operation for bleeding, ventilation time, ICU and hospital stay, wound infection, sternal dehiscence or fracture and 30 day mortality were collected. RESULTS: Mean patients age was 76.1 +/−9.4 years, 72% were female. Minimal-access AVR could be performed with a mean length of midline skin incision of 7.8 cm. Aortic cross-clamping time was 54.6 +/−6.3 min, cardiopulmonary bypass time 71.2+/−11.3 min and time of surgery 154.1 +/−26.8 min. Re-operation for bleeding had to be performed in 1 case (1.7%). There were no strokes or pacemaker implantations needed. Mean ventilation time was 4.5 h, ICU stay was 2 days and mean length of hospital stay was 6 days. 6 months follow up showed mortality of 0% and no sternal dehiscence or wound infection was observed. CONCLUSION: Minimal-access AVR via complete median sternotomy can be performed safely,in this elderly patient cohort without adding additional operative risk compared to conventional AVR. By avoidiance of large skin incisions this approach combines excellent cosmetic results with fast surgery time and excellent postoperative recovery