International AIDS Day provides an opportunity to examine the efforts to combat the deadly virus that attacks the human immune system. In South Africa, whose 5.7 million HIV victims make it the most affected country in the world, officials and activi...
Little girls are made of sugar and spice and, according to a study published in the journal Cell, a fierce determination to maintain their girlishness. Because it seems that a single gene keeps their ovaries from turning into testes. Scientists have...
In 1883, a creative engineer named John Roebling was inspired to build a spectacular[壮观的] bridge connecting New York with Long Island. However bridge-building experts throughout the world thought that this was an impossible feat and told Roebling...
