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The article presents information on the X chromosome. Men carry the X and Y chromosomes, while women carry two versions of the X chromosome. Researchers found that 10 percent of the 1,098 genes in the X chromosome of men are turned on in the testes. Inheriting a single X chromosome exposes men to diseases such as hemophilia or Duchenne muscular dystrophy.

Reports on the effects of enormous meteorite or comet that struck Earth 65 million years ago on Earth's ecology. Description of the impact of the meteorite that struck Earth; Physical evidence of the possible nuclear winter; Bottom-dwelling microbes that were found by Simone Galeotti of the University of Urbino in Italy.

Provides information on a study conducted by biologists led by Keith Barker of the University of Minnesota which suggested that most songbirds originated in Australasia. Difference between Corvida and Passerida, the major branches of songbirds; Methodology of the study.

Deals with a study on tubule bacteria found in South African volcanic rock. Information on tubules and isotopes; Comment from paleontologist Martin Brasier of Oxford University, on the study; Discussion on the function of the tubules.

Focuses on a study that examined the fossilized pterosaur embryo in China. Description of its wing membranes; Comment from David Unwin, a pterosaur expert at the museum of Natural History in Berlin, on the study.

Focuses on an inexpensive way to transform chlorofluorocarbons (CFC) into harmless minerals. Damages caused by CFCs to the environment; Description of the disposal method.