A heat engine gives greater efficiency when run with a large temperature difference. In the oceans the temperature difference between surface and deep water is greatest in the tropics, although still a modest 20 to 25 Â°C.
A blastocyst is a cellular mass that forms early in the process of embryo development in mammals. In humans, this stage of embryogenesis occurs five days after fertilization, when there are fewer than 100 cells in the mass.
The blastocyst is not only changing, it is literally traveling to a place to rest and grow and get good eats: a great first apartment. The egg travels through the fallopian tube by the movement of cilia, which are frilly cellular attachments, and muscle contractions. At the end of the journey the blastocyst comes to the uterus.