There were 77 passengers aboard United Flight 826, a Douglas DC-8 jetliner that, with a crew of seven, had wandered off course, apparently because of a problem with a navigational radio that was essential for flying in bad weather.
Aluminum is essential for flying machines like the F-35 joint strike fighter and Boeing F/A-18 Super Hornet, for armor plating on army vehicles and naval vessels and for countless infrastructure projects including bridges and roads.
These results highlight the intrinsic physiological properties of Rudolph's legendary luminous red nose, which help to protect it from freezing during sleigh rides and to regulate the temperature of the reindeer's brain, factors essential for flying reindeer pulling Santa Claus's sleigh under extreme temperatures.
Hel-N1, a human RNA-binding protein, shares significant homology with Drosophila protein ELAV, which is essential for fly neuronal development.
In collaboration with Dan Eberl's lab (University of Iowa) we showed that myosin VIIA is also essential for fly hearing -- remarkably, its human homolog is also required for human hearing, even though the mechanisms of auditory sensory reception in these phylogenetically diverged systems are very different.
Flies homozygous mutant for any of the four Sans alleles were adult viable, male and female fertile, and had no gross morphological defects (data not shown), indicating that Sans is not essential for fly development and fertility.
Since the flies do various rotations during maneuver, certain amount of mismatch between the actuation and sensing frequency of the haltere is essential for fly's sensing mechanism.
Embryos lacking centrosomes arrest early in development after only a few rounds of nuclear division, and several key PCM proteins such as Cnn, Spd-2, Asl and TACC that are not essential for fly viability are essential for these early stages of embryo development (Dix and Raff, 2007; Gergely et al., 2000; Megraw et al., 1999; Varmark et al., 2007).
To our surprise, plp mut embryos developed and hatched at near normal rates (Fig. 3B), demonstrating that, unlike proteins such as Cnn, Spd-2, Asl and TACC (that are not essential for fly viability, but are essential for early embryo development), PLP is not essential for mitosis even during the very rapid nuclear divisions of the syncytial embryo.
Furthermore, sufficient flight stability is essential for all flying animals and bird tails are thought to be a key component for overall flight stability [5], [6], [7].
When tethered and fixed in a position to gain lift from the wind, a kite maintains a perpetual stall a poor aerodynamic design for an airplane but essential for a kite flying at a stable and positive angle with respect to the horizon.
