One such illustration would be a cutaway of the Texas School Book depository featuring the sixth floor, the second floor, and the first floor. Oswald's possible path is shown in a broken line (beginning with the sixth floor window at 12:30 p.m. and ending with Oswald leaving MacNeil at 12:33 p.m.). Oswald's witnessed paths are then represented by solid lines. Inset clocks show the times at which established events occurred: the shots firing; Baker spotting Oswald; Reid seeing Oswald; and MacNeil stopping Oswald. For an actual depiction of this illustration, see Gerald Posner's book Case Closed: Lee Harvey Oswald and the Asssassination of JFK (New York: Random House, 1993), pages 480-481.
Imagine that it is 1985 and that the wreckage of the R.M.S. Titanic has just been located on the ocean floor. Surprisingly, the ship is in two pieces, separated by a distance of 0.4 miles. Create an illustration that shows what happened to the Titanic based on the following events that you assume to be true [Gannon, Popular Science, February 1995]:
At 11:40 p.m. on the night of April 12, 1912, the Titanic on its maiden voyage sideswipes an iceberg. The collision causes a huge gash in the ship's hull. By midnight, the first six compartments of the hull have filled to the point at which water was sloshing over from one compartment to the next. At 1:20, the bow dips to the point that water floods through the anchor chain holes. By 2:00, the bow has submerged so much that the three mammoth propellers in the stern lift free from the water. One of the stacks topples. At 2:10, the Titanic is tilted at least 45 degrees. The bending moment on the ship is immense, for a huge portion of the ship hangs unsupported. Suddenly, at a point at or just beneath the surface, the topside pulls apart, while the hull girder near the ship's center fails. The keel bends, and the bottom plating buckles. Within minutes, the stern angles high above the water. At 2:18, the bow, dangling beneath fills with water, grows heavier, and rips loose. Free from that weight, the stern rises sharply, holds almost a vertical position, and then fades downward again. At 2:20, the stern gently slides beneath the surface. Meanwhile the bow has been coasting down at a maximum speed of about 13 mph. At 2:29, it strikes the bottom, 12,612 feet beneath the ocean surface. At 2:56, the stern, having fallen nearly vertically at about 4 mph, crashes (nearly 36 minutes after submerging) two-fifths of a mile from the bow.
One such illustration would be a staged drawing showing the Titanic at different times. See Robert Gannon's article in Popular Science (February 1995).
Design an illustration to represent the stages in the life cycle of lymphocytes in the human immune system. The human immune system is made up of several parts: the bone marrow, the thymus gland, the lymph nodes, and the spleen. In the red bone marrow, certain cells, called lymphocytes, originate. Upon being released from the bone marrow, these lymphocytes are essentially identical, but may mature into one of two types of protective cells: T cells or B cells. Whether a given lymphocytes matures into a T cell or B cell depends on where in the body it becomes immunocompetent (able to recognize specific antigens). T cells arise from lymphocytes that migrate to the thymus gland, where they undergo a maturation process of two to three days. When this process is complete, immunocompetence in T cells is achieved. B cells are believed to develop immunocompetence while still in the bone marrow, but very little is known about the factors that control B cell maturation in humans.
Immunocompetence by a lymphocyte is signaled by the appearance of a single, unique type of cell surface receptor on each T cell or B cell that enables the lymphocyte to recognize and bind to a specific antigen. After becoming immunocompetent, both T cells and B cells disperse to the lymph nodes and spleen where they encounter antigens. When lymphocytes bind with recognized antigens, they complete their differentiation into fully mature T cells and B cells. Note that lymphocytes, particularly T cells, are extremely mobile and circulate continuously throughout the body. their circulatory pattern greatly increases their chances of coming into contact with antigens located in different parts of the body.
You have reached the end of this exercise.
One such illustration would be a combination drawing/diagram that shows key areas: immature lymphocytes in the bone marrow, some of these lymphocytes becoming immunocompetent T cells in the spleen, other lymphocytes becoming immunocompetent B cells in the bone marrow, the lymph nodes and spleen where both T cells and B cells migrate through, and the circulation of both mature T and B cells and immunocompetent T and B cells in the blood. An example exists in Elaine Marieb's Human Anatomy and Physiology (Benjamin /Cummings, 1989).
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