BIOE 301 HW #4

1. BIOE 301 HW #4 • Read the following excerpts from William Saletan’s Human Nature column on Slate.com and briefly explain whether the work described is science or engineering. • a. Scientists have grown and implanted the first custom-made human organs. They made bladders and put them in patients who donated the source tissue. Recipe: Take a tiny tissue sample from each patient, grow it in a dish, wrap it around a scaffold to shape it, grow it for seven weeks in an incubator, then put it in the patient, where the new bladder keeps growing. The bladders have been functioning in seven patients for about four years. Next, scientists plan to grow kidneys, livers, and hearts. • b. Smoking addiction can be erased by "knocking out" a tiny part of the brain. It's called the insula. In a study of brain-injured former smokers, half said their cravings had completely vanished. Three-quarters of this subset had suffered insula damage. "Smokers with damaged insulas were 136 times more likely to have their addictions erased than smokers with damage in other parts of their brains." Excited reactions: 1) We can help people quit smoking by targeting the insula. 2) Maybe we can target alcohol, cocaine, and gambling addiction the same way. Warning: "Damage to the insula is associated with slight impairment of some social function."

2. Read the following abstract from an article recently published in Nature. Briefly explain how the steps the authors took correspond to the steps of the scientific method. All five steps are represented here. • Letter: An unexpected cooling effect in Saturn's upper atmosphere • C. G. A. Smith, A. D. Aylward, G. H. Millward, S. Miller and L. E. Moore • The upper atmospheres of the four Solar System giant planets exhibit high temperatures1,2 that cannot be explained by the absorption of sunlight2,3. In the case of Saturn the temperatures predicted by models of solar heating2,4 are 200 K, compared to temperatures of 400K observed independently in the polar regions5 and at 30latitude6. This unexplained ‘energy crisis’ represents a major gap in our understanding of these planets’ atmospheres. An important candidate for the source of the missing energy is the magnetosphere1,2,4,7–9, which injects energy mostly in the polar regions of the planet. This polar energy input is believed to be sufficient to explain the observed temperatures9, provided that it is efficiently redistributed globally by winds4,8, a process that is not well understood. Here we show, using a numerical model4, that the net effect of the winds driven by the polar energy inputs is not to heat but to cool the low-latitude thermosphere. This surprising result allows us to rule out known polar energy inputs as the solution to the energy crisis at Saturn. There is either an unknown—and large—source of polar energy, or, more probably, some other process heats low latitudes directly.