First developed by the United States in the early 1950s, the hydrogen or thermonuclear bomb is perhaps a thousand times more powerful than a uranium-or plutonium-based fission bomb, making it effectively the nuclear weapon's nuclear weapon.n a fusion reaction, two atoms of the lightest element, hydrogen, fuse to create one atom of helium, the next-lightest element â and release much more energy.
Clival tumors were found to enhance intensely. A clivus of very low signal intensity (signal void) on T1- or T2-weighted images was always abnormal. The clivus with marrow reconversion was uniformly hypointense relative to the pons on T1-weighted images and isointense relative to normal marrow on T2-weighted images.
of His, which conducts the signal through the interventricular septum towards the apex of the heart. Soon after entering the interventricular septum the AV bundle bifurcates into two separate branches. The conduction of the electrical signal through the interventricular septum, coupled with the slow conduction velocity of the AV node, causes a delay from when action potentials form in atrial myocardium and when they form in the ventricular myocardium (and subsequently in when the two sets of chambers contract) called the atrioventricular delay. This delay ensures that atrial systole is complete at the onset of ventricular systole. Once the signal reaches the apex of the heart it is conducted up the lateral walls of the ventricle through branched tracts of pacemaker cells called Purkinje fibers, which distribute the electrical signal to the ventricular myocardium. Electrical changes occurring during the cardiac cycle can be monitored from the surface of the body in a recording called an electrocardiogram (ECG, or EKG). A normal