Thrust enhancement and degradation mechanisms due to self-induced vibrations in bio-inspired flying robots.

Bio-inspired flying robots (BIFRs) which fly by flapping their wings experience continuously oscillating aerodynamic forces. These oscillations in the driving force cause vibrations in the motion of the body around the mean trajectory. In other words, a hovering BIFR does not remain fixed in space; instead, it undergoes oscillatory motion in almost all directions around the stationary point. These oscillations affect the aerodynamic performance of the flier. Assessing the effect of these oscillations, particularly on thrust generation in two-winged and four-winged BIFRs, is the main objective of this work. To achieve such a goal, two experimental setups were considered to measure the average thrust for the two BIFRs. The average thrust is measured over the flapping cycle of the BIFRs. In the first experimental setup, the BIFR is installed at the end of a pendulum rod, in place of the pendulum mass. While flapping, the model creates a thrust force that raises the model along the circular trajectory of the pendulum mass to a certain angular position, which is an equilibrium point and is also stable. Measuring the weight of the BIFR and the equilibrium angle it obtains, it is straightforward to estimate the average thrust, by moment balance about the pendulum hinge. This pendulum setup allows the BIFR model to freely oscillate back and forth along the circular trajectory about the equilibrium position. As such, the estimated average thrust includes the effects of these self-induced vibrations. In contrast, we use another setup with a load cell to measure thrust where the model is completely fixed. The thrust measurement revealed that the load cell or the fixed test leads to a higher thrust than the pendulum or the oscillatory test for the two-winged model, showing the opposite behavior for the four-winged model. That is, self-induced vibrations have different effects on the two BIFR models. We felt that this observation is worth further investigation. It is important to mention that aerodynamic mechanisms for thrust generation in the two and four-winged models are different. A two-winged BIFR generates thrust through traditional flapping mechanisms whereas a four-winged model enjoys a clapping effect, which results from wing-wing interaction. In the present work, we use a motion capture system, aerodynamic modeling, and flow visualization to study the underlying physics of the observed different behaviors of the two flapping models. The study revealed that the interaction of the vortices with the flapping wing robots may play a role in the observed aerodynamic behavior of the two BIFRs.

Anti-snake Venom-Induced Kounis Syndrome: A Unique Case in the Emergency Department.

Kounis syndrome is the concurrence of acute coronary syndromes associated with allergic or hypersensitivity and anaphylactic or anaphylactoid triggers. Although it is not a rare diagnosis, the different presentations and afflictions of all ages, sex, and racial groups make it a diagnostic challenge. Various triggers include food types, environmental exposure, and drugs. Cases triggered by serum sickness, tetanus antitoxin, and snake bites have been documented in the literature. However, to the best of our knowledge, no case triggered by anti-snake venom (ASV) has been reported yet, as seen in our patient. ASV is composed of refined F(ab)2 fragments of immunoglobulin G purified from horse or sheep plasma that has been immunized with the venom of different snake species. Evidence of hypersensitivity has been reported with ASV but not with Kounis syndrome. More so, various other vaccinations have also been associated with Kounis syndrome. We present the case of a 30-year-old male who presented to the emergency department with post-snake bite envenomation and neurological symptoms. After the initiation of the anti-snake venom, the patient's neurological signs improved. However, the patient developed acute chest pain. His ECG showed transient ST elevation, and cardiac enzymes and serum IgE levels were raised. A diagnosis of Kounis syndrome was made, and the patient was managed accordingly.

Point of care ultrasound as initial diagnostic tool in acute dyspnea patients in the emergency department of a tertiary care center: diagnostic accuracy study.

BACKGROUND: Dyspnea is one of the common symptoms patients present to the emergency department (ED). The broad spectrum of differentials often requires laboratory and radiological testing in addition to clinical evaluation, causing unnecessary delay. Point of care ultrasound (PoCUS) has shown promising results in accurately diagnosing patients with dyspnea, thus, becoming a popular tool in ED while saving time and maintaining safety standards. Our study aimed to determine the utilization of point of care ultrasound in patients with acute dyspnea as an initial diagnostic tool in our settings. METHODOLOGY: The study was conducted at the emergency department of a tertiary healthcare center in Northern India. Adult patients presenting with acute dyspnea were prospectively enrolled. They were clinically evaluated and necessarily investigated, and a provisional diagnosis was made. Another EP, trained in PoCUS, performed the scan, blinded to the laboratory investigations (not the clinical parameters), and made a PoCUS diagnosis. Our gold standard was the final composite diagnosis made by two Emergency Medicine consultants (who had access to all investigations). Accuracy and concordance of the ultrasound diagnosis to the final composite diagnosis were calculated. The time to formulate a PoCUS diagnosis and final composite diagnosis was compared. RESULTS: Two hundred thirty-seven patients were enrolled. The PoCUS and final composite diagnosis showed good concordance (κ = 0.668). PoCUS showed a high sensitivity for acute pulmonary edema, pleural effusion, pneumothorax, pneumonia, pericardial effusion, and low sensitivity for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). High overall specificity was seen. A high positive predictive value for all except left ventricular dysfunction, pericardial effusion, non-cardiopulmonary causes of dyspnea, and a low negative predictive value was seen for pneumonia. The median time to make a PoCUS diagnosis was 16 (5-264) min compared to the 170 (8-1346) min taken for the final composite diagnosis. Thus, time was significantly lower for PoCUS diagnosis (p value <0.001). CONCLUSION: By combining the overall accuracy of PoCUS, the concordance with the final composite diagnosis, and the statistically significant reduction in time taken to formulate the diagnosis, PoCUS shows immense promise as an initial diagnostic tool that may expedite the decision-making in ED for patients' prompt management and disposition with reliable accuracy.

Marijuana-induced acute myocardial infarction in a young adult male.

A 27-year-old man presented to the emergency department of a tertiary care centre with complaints of acute onset breathing difficulty and retrosternal chest discomfort of 6 hours' duration. On primary survey, he was dyspnoeic with a room air saturation of 85% and a blood pressure of 80/50 mm Hg. A bedside ultrasound revealed an ejection fraction of around 40%, with hypokinesia of interventricular septum, left ventricular apex and anterior wall with bilateral multiple B lines in all lung zones. A 12 lead ECG showed ST segment elevation in leads V2-V6. He sustained a cardiac arrest. Return of spontaneous circulation was achieved following high-quality cardiopulmonary resuscitation. After successful resuscitation, the patient underwent primary percutaneous coronary intervention and recovered fully from the event. On further evaluation, an acute binge of marijuana smoking prior to the onset of symptoms was identified as the cause of the acute coronary syndrome.