Letters to the Editor

19153

Your article describes the economic and environmental costs of semiconductor chips. Interestingly, the impacts on the environment are very similar for the manufacture of solar cells. Many environmentalists place such unrealistic expectations on solar cell energy that they overlook certain facts. First, solar cells yield at most 30 percent efficiency. Second, solar cells do not […]

19152

It’s not surprising that training may enhance intellect in the elderly. What would be remarkable would be for the elderly to be completely incapable of learning. The real question is whether cognitive training works against whatever causes cognitive decline in the elderly or whether it merely boosts base-level ability. The former would be indicated only […]

19197

The article notes that X-ray radiation from XTE J1550-54 jets is puzzling because the radiation of the nearer jet, which is moving toward Earth, isn’t as bright as that of the more distant jet.