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Oxygen Depletion: A New Form Of Ocean Habitat Loss
An international team of physical oceanographers including a researcher from Scripps Institution of Oceanography at UC San Diego has discovered that oxygen-poor regions of tropical oceans are expanding as the oceans warm, limiting the areas in which predatory fishes and other marine organisms can live or enter in search of food.
The new study is led by Lothar Stramma from the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany, and is co-authored by Janet Sprintall, a physical oceanographer at Scripps Oceanography and others. The researchers found through analysis of a database of ocean oxygen measurements that levels in tropical oceans at a depth of 300 to 700 meters (985 to 2,300 feet) have declined during the past 50 years. The ecological impacts of this increase could have substantial biological and economical consequences.
“We found the largest reduction in a depth of 300 to 700 meters (985 to 2,300 feet) in the tropical northeast Atlantic, whereas the changes in the eastern Indian Ocean were much less pronounced,” said Stramma. “Whether or not these observed changes in oxygen can be attributed to global warming alone is still unresolved. The reduction in oxygen may also be caused by natural processes on shorter time scales.”
Sprintall said the oxygen-poor areas have the potential to move into coastal areas via currents that flow from the mid-depth tropical oceans, where the oxygen changes were observed, and along the west coast of continents.
“The width of the low-oxygen zone is expanding deeper but also shoaling toward the ocean surface,” said Sprintall, a specialist in observing changes of fluxes in ocean properties such as heat distribution.
Sprintall contributed data to the study gathered during recent cruises undertaken as part of the Climate Variability and Predictability (CLIVAR) program, a long-running study operated by the World Climate Research Programme that seeks to understand climate through ocean-atmosphere interactions.
The study, “Expanding Oxygen-Minimum Zones in the Tropical Oceans,” appears in the May 2 edition of the journal Science. The research team includes Stramma, Sprintall, NOAA scientist Gregory Johnson, and Volker Mohrholz from the Institute for Baltic Sea Research in Warnem??nde, Germany.
The team selected ocean regions for which they could obtain the greatest amount of data to document the decline in oxygen. Some of the more recent data came from oxygen sensors which have been added to about 150 of the profiling floats used in Argo, a worldwide network of sensors that track basic ocean conditions such as temperature and salinity. There are more than 3,000 Argo floats operating in the world’s oceans, and Sprintall said the quality of the data gathered by the Argo floats suggests that more units in the network should be outfitted with oxygen sensors.
Lisa Levin, a biological oceanographer at Scripps Oceanography who studies oxygen-minimum zones that intercept the seafloor, said an expansion of oxygen-minimum zones in the oceans could lead to diminished biodiversity and to the expanded distributions of organisms that have adapted to live in hypoxic, or oxygen-poor waters.
“I think it’s uncharted territory,” said Levin, who was not affiliated with the study. “Thicker oxygen minimum zones could affect nutrient cycling, predator-prey relationships and plankton migrations. Where the expanding oxygen-minimum zones impinge on continental margins, we could see huge ecosystem changes.”
[Rob Monroe and Mario Aguilera @ UC San Diego]
VMware and Parallels for Virtual Machines
It doesn't matter if you're running on Windows or Mac OS X - every power user needs either Parallels or VMware (or both). There's never been an easier way to test software without destroying your primary operating system's stability. Think of how many times you wish you could press a 'reverse' button on your computer. Plus, there's no easier way to try new Linux distributions - see what all the fuss is about. Run Windows in OS X, run Linux in Windows, but the best way to do either is with VMware and/or Parallels.
Socrates In The Classroom Develops Students’ Thinking
When students have the opportunity to participate in “Socratic seminars” on a regular basis, a different classroom culture evolves. The students collaborate more and more voices are heard. The students develop their thinking skills in a cooperative and investigative atmosphere. This is shown in a new dissertation in Pedagogy by Ann S. Pihlgren at the Stockholm University in Sweden.
The Socratic dialogue is a particular way of developing children’s, as well as adults’, thinking skills through cooperative dialogue where significant human ideas and values are discussed. By participating in Socratic seminars regularly every other week, preschool children and older students develop their thinking skills. The seminars address literature and art work, with questions such as these: is Pippi Longstocking a good friend, is Jack stupid or smart when he sells his mother’s cow for some beans, or are we born good or evil? In the beginning the students have difficulty expressing their thoughts, but with time their ability to express themselves and to examine ideas critically and logically develops.
The study included seven groups of children, five to sixteen years old. The groups were filmed during three years of philosophizing in the classroom and the films were analyzed. The interaction in the classroom was positively influenced, according to Ann S Pihlgren. The teacher dominated less, more students spoke and the students gradually took over the responsibilities of the teacher to promote exploration in the dialogue. The ability to use the Socratic seminar is learned by students and teachers through practice and by testing the rules of the seminar. The students construct a supportive group culture through their silent interaction, where gestures, glances, and body language are used to show not only support or sympathy for each other, but also cooperation with each other when someone attempts to disturb or to provoke the dialogue. The teacher role changes to one of support, ensuring that the analysis is fruitful and that the dialogue is respectful.
Socratic methods have developed independently in various countries. They all describe a set of methodological steps to attain similar objectives. An opening question is answered by all participants and followed by cooperative, critical analysis. Finally, the new ideas are connected to the everyday life experience of the participants.
It seems as if this ritualized structure and the nurturing culture of the seminar provide a safe circle, helping the participants to try new, bold ideas that they might otherwise not have tested, Ann S. Pihlgren says. By cooperating when examining the ideas they also seem to learn a way to address problems on their own without teacher intervention.
To work with methods connected to the ancient philosopher Socrates may seem out-of-date in a modern school, but that is absolutely not the case, Ann S. Pihlgren states.
The Socratic seminars have been seen as a complement to traditional classroom teaching for hundreds of years. But it is not easy to learn how to stage them to get positive effects. It is especially hard for teachers, who often fall back to their traditional, controlling “teacher” roles. The dissertation offers excellent tools for teachers who want to develop students’ thinking and to foster cooperative group dialogue.
The name of the dissertation: Socrates in the Classroom. Rationales and Effects of Philosophizing with Children. The dissertation can be downloaded as a pdf here.
[Jonas Ablad @ Swedish Research Council]
Is Miley Cyrus the next child star train wreck?
"For parental inattention beyond mind-boggling with a 15-year-old, Rosemond's Awfully Ludicrous Parenting Honor goes to...yes!...LETICIA and BILLY RAY CYRUS!"
Scene: The 2008 RALPH Awards, held at a highly secret location somewhere in the Northern Hemisphere. via Reno Gazette-Journal
Undergrad Has Sweet Success With Invention of Artificial Golgi
An undergraduate student at Rensselaer Polytechnic Institute has learned very quickly that a spoonful of sugar really does help the medicine go down. In fact, with his invention, the sugar may actually be the medicine.
Among the most important and complex molecules in the human body, sugars control not just metabolism but also how cells communicate with one another. Graduating senior Jeffery Martin has put his basic knowledge of sugars to exceptional use by creating a lab-on-a-chip device that builds complex, highly specialized sugar molecules, mimicking one of the most important cellular structures in the human body — the Golgi Apparatus.
“Almost completely independently he has been able to come closer than researchers with decades more experience to creating an artificial Golgi,” said Robert Linhardt, the Ann and John H. Broadbent Jr. ‘59 Senior Constellation Professor of Biocatalysis and Metabolic Engineering at Rensselaer and Martin’s adviser. “He saw a problem in the drug discovery process and almost instantly devised a way to solve it.”
Cells build sugars in a cellular organelle known as the Golgi Apparatus. Under a microscope, the Golgi looks similar to a stack of pancakes. The strange-looking organelle finishes the process of protein synthesis by decorating the proteins with highly specialized arrangements of sugars. The final sugar-coated molecule is then sent out into the cell to aid in cell communication and to help determine the cell’s function in the body.
Martin’s artificial Golgi functions in a surprisingly similar way to the natural Golgi, but he gives the ancient organelle a very high-tech makeover. His chip looks similar to a miniature checker board where sugars, enzymes, and other basic cell materials are suspended in water and can be transported and mixed by applying electric currents to the destination squares on the checker board. Through this process sugars can be built in an automated fashion where they are exposed to a variety of enzymes found in the natural Golgi. The resulting sugars can then be tested on living cells either on the chip or in the lab to determine their effects. With the chip’s ability to process many combinations of sugars and enzymes, it could help researchers quickly uncover new sugar-based drugs, according to Martin.
Scientists have known for years that certain sugars can serve as extremely beneficial therapeutics for humans. One well-known example is heparin, which is among the most widely used drugs in the world. Heparin is formed naturally in the Golgi organelle in cells of the human body as well as in other animals like pigs. Heparin acts as an anticoagulant preventing blood clots, which makes it a good therapeutic for heart, stroke, and dialysis patients.
The main source of heparin is currently the intestines of foreign livestock and, as recent news reports highlight, the risk of contamination from such sources is high. So researchers are working around the clock to develop a safer, man-made alternative to the drug that will prevent outside contamination. A synthetic alternative would build the sugar from scratch, helping eliminate the possibility of contamination he explained.
“I am very grateful to have the privilege of working with Dr. Linhardt who has discovered the recipe to make fully synthetic heparin,” Martin said. “Because we know the recipe, I am going to use it as a model to test the device. If our artificial Golgi can build fully functional heparin, we can then use the artificial organelle to produce many different sugar variants by altering the combination of enzymes used to synthesize them. Another great thing about these devices is that they are of microscale size, so that if needed we could fill an entire room with them to increase throughput for drug discovery.”
There are millions of possible sugar combinations that can be formed and scientists currently only know the function of very few of them like heparin. “Since it is known that these types of sugars play a part in many important biological processes such as cell growth, cell differentiation, blood coagulation, and viral defense mechanisms, we feel that that this artificial Golgi will help our team to develop a next generation of sugar-based drugs, known as glycotheraputics,” Martin said. “We are going to start making new combinations and we simply don’t know what we are going to find. We could find a sugar whose signal blocks the spread of cancer cells or initiates the differentiation of stem cells. We just don’t know.”
Martin, a Barry M. Goldwater Scholar and native of the small town of Boylston, Mass., is graduating from Rensselaer on May 17, 2008 with a nearly perfect GPA. He plans to continue on at Rensselaer as a graduate student, working with Linhardt to test and further develop his artificial Golgi.
[Gabrielle DeMarco @ Rensselaer Polytechnic Institute]
