Answer:
it was only 90 percent effective
Explanation:
In 1954 a massive controlled field trial was launched, sponsored by the National Foundation for Infantile Paralysis. Almost two million U.S. children between the ages of six and nine participated. In some areas of the country half of these “Polio Pioneers” received the vaccine, while half received a placebo. In other areas of the country children who did not receive any vaccine were carefully observed. On April 12, 1955, Thomas Francis, Salk’s mentor and the director of the trial, reported that the vaccine was safe, potent, and 90% effective in protecting against paralytic poliomyelitis.
Answer:
Examples of mechanical weathering include frost and salt wedging, unloading and exfoliation, water and wind abrasion, impacts and collisions, and biological actions. All of these processes break rocks into smaller pieces without changing the physical composition of the rock.
Explanation:
Mechanical weathering involves mechanical processes that break up a rock: for example, ice freezing and expanding in cracks in the rock; tree roots growing in similar cracks; expansion and contraction of rock in areas with high daytime and low nighttime temperatures; cracking of rocks in forest fires, and so forth.
Answer:
C. a pre-synaptic neuron involved in egg-laying
Explanation:
Serotonin (5-HT) is a neurotransmitter, i.e., a molecule that binds to specific receptors and thus transmits signals from one pre-synaptic neuron to another target cell. In humans, serotonin is involved in many physiological functions including sleep, mood, emotions, appetite, digestion, etc. Moreover, <em>Caenorhabditis elegans</em> is a model organism widely used in neuroscience research in order to understand neuromodulation at the level of individual neurons. In <em>C. elegans,</em> serotonin modifies behavior by regulating neuronal excitability and synaptic efficiency. Moreover, also in <em>C. elegans,</em> it has been shown that serotonin induces egg-laying and also provides a feedback regulatory mechanism by inhibiting the activity of the pre-synaptic neurons that release it. In consequence, in this case, it is expected that serotonin rescues the loss of function of serotonin receptors required for egg-laying by providing a regulatory feedback loop that contributes to serotonin adaptation.
Cell,tissues ,Organs and Organ Systems. After tissues, organs are the next level of organization of the human body. An organ is a structure that consists of two or more types of tissues that work together to do the same job. Examples of human organs include the brain, heart, lungs, skin, and kidneys
