Key Concepts. 1  The electrons on the outermost energy level of the atom are called valence electrons. 2  The valence electrons are involved in bonding one atom to another. 3  The attraction of each atomâs nucleus for the valence electrons of the other atom pulls the atoms together.
NTSC is the format used in the United States and Canada. NTSC stands for National Television Standard Committee which established the American TV broadcast TV standard as a 525 line broadcast. The NTSC system has higher frame rate (60 Hz) which reduces visible flicker and picture noise.
Neural tube defects (NTDs) are birth defects of the brain and spinal cord. They happen in about 3,000 pregnancies each year in the United States. A babyâs neural tube normally develops into the brain and spinal cord. It starts out as a tiny, flat ribbon that turns into a tube by the end of the first month of pregnancy.