Monday, July 20, 2009
A hypothesis of how to look for this evidence has been published in the journal Australian Physics and was presented at the first lecture in the 2009 July Lectures in Physics program at the University of Melbourne last week.
If correct, the discovery would be the first new planet identified by humanity since deep antiquity.
Galileo was observing the moons of Jupiter in the years 1612 and 1613 and recorded his observations in his notebooks. Over several nights he also recorded the position of a nearby star which does not appear in any modern star catalogue.
"It has been known for several decades that this unknown star was actually the planet Neptune. Computer simulations show the precision of his observations revealing that Neptune would have looked just like a faint star almost exactly where Galileo observed it," Professor Jamieson says.
But a planet is different to a star because planets orbit the Sun and move through the sky relative to the stars. It is remarkable that on the night of January 28 in 1613 Galileo noted that the "star" we now know is the planet Neptune appeared to have moved relative to an actual nearby star."
There is also a mysterious unlabeled black dot in his earlier observations of January 6, 1613, which is in the right position to be Neptune.
"I believe this dot could reveal he went back in his notes to record where he saw Neptune earlier when it was even closer to Jupiter but had not previously attracted his attention because of its unremarkable star-like appearance."
If the mysterious black dot on January 6 was actually recorded on January 28, Professor Jamieson proposes this would prove that Galileo believed he may have discovered a new planet.
By using the expertise of trace element analysts from the University of Florence, who have previously analyzed inks in Galileo's manuscripts, dating the unlabelled dot in his notebook may be possible. This analysis may be conducted in October this year.
"Galileo may indeed have formed the hypothesis that he had seen a new planet which had moved right across the field of view during his observations of Jupiter over the month of January 1613," Professor Jamieson says.
"If this is correct Galileo observed Neptune 234 years before its official discovery."
But there could be an even more interesting possibility still buried in Galileo's notes and letters.
"Galileo was in the habit of sending a scrambled sentence, an anagram, to his colleagues to establish his priority for the sensational discoveries he made with his new telescope. He did this when he discovered the phases of Venus and the rings of Saturn. So perhaps somewhere he wrote an as-yet undecoded anagram that reveals he knew he discovered a new planet," Professor Jamieson speculates.
University of Melbourne
Iron and manganese compounds, in addition to sulfate, may play an important role in converting methane to carbon dioxide and eventually carbonates in the Earth's oceans, according to a team of researchers looking at anaerobic sediments. These same compounds may have been key to methane reduction in the early, oxygenless days of the planet's atmosphere.
"We used to believe that microbes only consumed methane in marine anaerobic sediment if sulfate was present," said Emily Beal, graduate student in geoscience, Penn State. "But other electron acceptors, such as iron and manganese, are more energetically favorable than sulfate."
Microbes or groups of microbes -- consortia -- that use sulfates to convert methane for energy exist in marine sediments. Recently other researchers have identified microbes that use forms of nitrogen in fresh water environments to convert methane.
"People had speculated that iron and manganese could be used, but no one had shown that it occurred by incubating live organisms," said Beal.
Beal, working with Christopher H. House, associate professor of geoscience, Penn State, and Victoria J. Orphan, assistant professor of geobiology, California Institute of Technology, incubated a variety of marine sediments to determine if there were microbes that could convert methane to carbon dioxide without using any sulfur compounds.
Using samples of marine sediment taken 20 miles off the California coast and about 1,800 feet deep near methane seeps in the Pacific, Beal incubated a variety of sediment systems including as controls, an autoclaved sterile sample, a sample with sulfate as a control and a sample that was sulfate, iron oxide and manganese oxide free, but live. She also incubated samples that were sulfate free but contained iron oxide or manganese oxide. She placed methane gas that contained the non-radioactive carbon-13 isotope in the empty space in the flasks above the sediment and tested any resulting carbon dioxide produced by the samples. All the carbon dioxide had the carbon-13 isotope and so came from the methane samples.
The sterile control showed no activity, while the live control without sulfate showed minute activity. The sulfate control showed the most activity as expected, but both the iron and manganese oxide-laced samples showed activity, although less activity than the sulfate.
"We do not think that iron and manganese are more important than sulfate reduction today, but they are not trivial components," said House, who is director of Penn State's Astrobiology Research Center. "They are probably a big part of the carbon cycle today."
One reason they are important is that some of the carbon dioxide produced reacts with both the manganese and iron to form carbonates that precipitate and sequester carbon in the oceans. Even if the carbon dioxide escaped into the atmosphere, it is a less problematic greenhouse gas than methane.
On the early Earth, where oxygen was absent from the atmosphere, sulfates were scarce. Without sulfates, iron and manganese oxides may have been essential in converting methane to carbon dioxide.
"Sulfate comes mostly from oxidative weathering of rocks," said Beal. "Oxygen is needed for this to occur."
While manganese and iron oxides are made in today's oxygen atmosphere, they where also formed by photochemical reactions in a low oxygen atmosphere. These oxides were probably more abundant in the early Earth's oceans than sulfates.
While Beal has categorized the more than a dozen microorganisms living in the sediments she used, she does not know which of these microbes is responsible for consuming methane. It might be one bacteria or archaea species, or it may be a consortium of microbes. She is trying to identify the organisms responsible.
(Photo: Emily Beal, Penn State)
A new study suggests activities combining movement and force tax our brains to capacity, countering a long-held belief that difficulty with dexterous tasks results from the limits of the muscles themselves. The findings may help explain why minor damage to the neuromuscular system can at times profoundly affect one's ability to complete everyday tasks.
The research, supported in part by the National Science Foundation and the National Institutes of Health, appeared in the July 8, 2009, Journal of Neuroscience.
"Our results show how much the mechanics of the body, and a given task, affect what the brain can or can't do," said Francisco Valero-Cuevas of the Brain-Body Dynamics Lab at the University of Southern California, who led the research. "The so-called 'problem' of muscle redundancy--having too many muscles and joints to control--may not be the only challenge the brain faces when controlling our bodies. Rather, we seem to have about as many muscles as we need, and not too many, as others have proposed in the past."
"The scientific world and the clinical world have long been arriving at conflicting conclusions, and this work begins to resolve the paradox," added Valero-Cuevas. "While neuroscience and biomechanics studies have suggested that muscles and joints are, in theory, redundant and provide numerous alternative solutions to simple tasks, clinicians routinely see people seeking treatment for hand disability resulting from relatively minor conditions such as aging."
This research follows earlier experiments that suggested our brain and complex musculature can barely keep up with requirements posed by our anatomy and the mechanics of even ordinary, real-world, finger tasks like rubbing a surface. The conclusions begin to explain why even minor damage to the neuromuscular system seems to produce real deficits in manipulation.
The research focused on simultaneous force and motion--specifically from fingers either pushing or rubbing a surface--with volunteers conducting the experiment at defined, yet varying, speeds.
Knowing the force-producing properties of muscle, the researchers expected the rubbing motion would show reduced downward force as the speed of motion increased. Surprisingly, whether rubbing slowly or at a pace 36-times faster, speed had little affect on the downward force the volunteers could produce.
Valero-Cuevas and his collaborators--his former students Kevin G. Keenan of the University of Wisconsin/Milwaukee, Veronica J. Santos of Arizona State University, and Madhusudhan Venkadesan of Harvard University--interpret the results to mean the brain is sufficiently occupied by the physical demands of combining motions and forces, so the muscle properties are not the limiting factors for how much force the fingers can create.
"This begins to explain the clinical reality that when something in the system is damaged, either in the brain or body, we can see losses of function," said Valero-Cuevas. "We are not as 'redundant' as we thought."
The study is part of an ongoing NSF Emerging Frontiers in Research and Innovation study to understand how to achieve dexterous, near-optimal control of a hand by having humans and computers perform familiar, challenging tasks. In that effort, researchers will use the same algorithms both to model human motor control and to go beyond the present state-of-the-art in robotic manipulation.
The research team is conducting additional research to determine what exact neural and anatomical mechanisms are producing these results.
(Photo: USC Viterbi)