RESUMO
Protons with energies up to approximately 10(15) eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (pi(0)), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in gamma-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from gamma-rays at energies of approximately 10(12) eV hitting Earth's upper atmosphere, in the direction of the supernova remnant RX J1713.7-3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.
RESUMO
In this report, the left ventricular blood pool of the heart is presented as an image of three dimensions by collecting the data simultaneously with two scintillation cameras from two directions at right angles to one another and processing by a computer system. Our three dimensional procedures, quite different from the conventional two dimensional images, reproduce the cubic structure of the left ventricle. It was confirmed by basic experiments using several phantoms that this three dimensional image reproduced the shape of the object very accurately. The three dimensional images of the left ventricle clearly showed morphological changes and abnormalities in myocardial movement. It is highly valuable in diagnosis because foci of myocardial infarction, akinesis and dyskinesis are clearly detected by this technique. In particular, the fact that the three dimensional images conform well with X-ray cineangiography and 201T1 scanning justifies the value of the clinical application of this technique.
