In 1929 the American astronomer Edwin Hubble discovered that the distances to far-away galaxies were proportional to their redshifts. Redshift occurs when a light source moves away from its observer: the light's apparent wavelength is stretched via the Doppler effect towards the red part of the spectrum. Hubble’s observation implied that distant galaxies were moving away from us, as the furthest galaxies had the fastest apparent velocities. If galaxies are moving away from us, reasoned Hubble, then at some time in the past, they must have been clustered close together.
Catheter was used to remove excess fluid from pleural space. it is necessary to drain air, secretions and blood from thoracic space in order to allow normal expansion of lungs. when surgeon places a catheter in the chest, they provide a drainage route that removes excess air and other body fluids that may build up. in some occasions two catheters are installed after surgery, one posteriorly and the other anteriorly.
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<span>Examples would be epinephrine or adrenaline and
norepinephrine. These are neurotransmitters of the sympathetic nervous system
which is responsible for fight/flight response during situations that either
threatens the host’s survival. Now, these neurotransmitters vasodilate the
blood vessels increasing the flow of blood to many vital organs. Physiologically,
increased heart rate, increased motor function and dilated pupils are some of
the biological reactions to stressful situations. </span>
