Snakes, fish, chickens, and humans all begin life in much the same way. Early in their transformation from an amorphous blob of cells into a fully developed animal, growing cells pinch off into a string of identical segments destined to become individual vertebrae, which will later sprout blood vessels, peripheral nerves, and muscle. These repeated segments ensure that the rod-like spinal column can hunch, arch, and twist.
The segmentation process also helps establish some key differences in the body plans of different organisms: while humans have 33 vertebrae, frogs have 10 or fewer, and snakes can have more than 300. …
NASA’s Phoenix Mars Lander performed its first wet chemistry experiment on Martian soil flawlessly yesterday, returning a wealth of data that for Phoenix scientists was like winning the lottery.
“We are awash in chemistry data,” said Michael Hecht of NASA’s Jet Propulsion Laboratory, lead scientist for the Microscopy, Electrochemistry and Conductivity Analyzer, or MECA, instrument on Phoenix. “We’re trying to understand what is the chemistry of wet soil on Mars, what’s dissolved in it, how acidic or alkaline it is. With the results we received from Phoenix yesterday, we could begin to tell what aspects of the soil might support life.”
“This is the first wet-chemical analysis ever done on Mars or any planet, other than Earth,” said Phoenix co-investigator Sam Kounaves of Tufts University, science lead for the wet chemistry investigation.
About 80 percent of Phoenix’s first, two-day wet chemistry experiment is now complete. Phoenix has three more wet-chemistry cells for use later in the mission.
Stimulant medications such as Ritalin have been prescribed for decades to treat attention deficit hyperactivity disorder (ADHD), and their popularity as “cognition enhancers” has recently surged among the healthy, as well.
What’s now starting to catch up is knowledge of what these drugs actually do in the brain. In a paper publishing online this week in Biological Psychiatry, University of Wisconsin-Madison psychology researchers David Devilbiss and Craig Berridge report that Ritalin fine-tunes the functioning of neurons in the prefrontal cortex (PFC) — a brain region involved in attention, decision-making and impulse control — while having few effects outside it.
Because of the potential for addiction and abuse, controversy has swirled for years around the use of stimulants to treat ADHD, especially in children. By helping pinpoint Ritalin’s action in the brain, the study should give drug developers a better road map to follow as they search for safer alternatives….
The analysis of the youngest pair of identical twin stars yet discovered has revealed surprising differences in brightness, surface temperature and possibly even the size of the two.
The study, which is published in the June 19 issue of the journal Nature, suggests that one of the stars formed significantly earlier than its twin. Because astrophysicists have assumed that binary stars form simultaneously, the discovery provides an important new test for successful star formation theories, forcing theorists back to the drawing board to determine if their models can produce binaries with stars that form at different times.