The thyroid hormones are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine, which has a longer half-life than T3. In humans, the ratio of T4 to T3 released into the blood is sometimes c
Similarly, the National Institutes of Health (NIH) requires that all trainees, fellows, participants, and scholars receiving support through any NIH training, career development award (individual or institutional), research education grant, or dissertation research grant must receive RCR training.
Additionally, the research design must make clear the procedures used to ensure the protection of research subjects, whether human or animal, and to maintain the integrity of the information collected in the study. There are many ways to design a study to test a hypothesis. The research design that is chosen depends on the type of hypothesis (e.g. Does X cause Y? or How can I describe X and Y? or What is the relationship between X and Y?), how much time and money the study will cost, and whether or not it is possible to find participants.