O conhecimento da incerteza de uma medida é crucial para obter conclusões a partir de resultados experimentais. Erros aleatórios, comuns em experimentos, produzem uma distribuição dos valores medidos que segue o formato gaussiano. Neste trabalho desenvolvemos uma montagem baseada no fenômeno de queda livre para auxiliar na ilustração do conceito de incerteza em medidas. Os tempos de queda de um objeto foram obtidos automaticamente pela placa Arduino e exibidos na forma de um histograma na tela do computador. A visualização do histograma foi feita em tempo real e permitiu verificar o aparecimento do aspecto gaussiano à medida que repetições do experimento eram realizadas.

The knowledge of the uncertainty of a measurement is crucial to draw conclusions from experimental results. Random errors are common in experiments and they produce a distribution of measured values that follows the Gaussian shape. In this work, we developed an apparatus based on the free fall phenomenon to assist in the illustration of the concept of uncertainty in measurements. The free fall time of an object has been obtained automatically by the Arduino board and displayed as a histogram on the computer screen. The visualization of the histogram was produced in real time and allowed to check the appearance of the Gaussian shape as the experiment was repeated.

OBJECTIVE: To establish the normal pattern and safety of echocardiographic contrast in patients with no significant obstruction of epicardial coronary arteries. METHODS: 67 patients with normal coronary arteries or obstructions < 50% were selected from 277 patients who underwent coronary angiography (CA). Mean age was 56 ± 11years and 36 were males. At the end CA, echocardiographic contrast was selectively injected into each coronary artery. The parasternal short axis of the left ventricle (LV) was divided into six segments: anterior (A), antero-lateral (AL), postero-lateral (PL), posterior (P), infero-septal (IS) and antero-septal (AS). Anterolateral (ALPM) and posteromedial papillary muscles (PMPM) were also considered. The pattern and intensity of the appearance of the myocardial contrast was visually analyzed. RESULTS: The right coronary artery (RCA) was dominant in 60 patients. Contrast appearance was sudden and simultaneous in the 3 muscle layers. All segments could be contrasted after the injection in both coronary arteries. 100% of the AS, A and AL segments, 97% of the PL and 98% of the ALPM were perfused by the left coronary artery (LCA). P and IS segments were perfused by the RCA in 85% and 82%, respectively, and by a dominant LCA in 71% of the cases. The PMPM was perfused by a dominant RCA in 77% and by a dominant LCA in 86%. There were no symptoms. CONCLUSION: Intracoronary injection of the sonicated solution is a safe procedure that allows for an excellent opacification of the myocardium and can potentially be used during routine CA.