Math Gains Reported for U.S. Students
American fourth- and eighth-grade students made solid achievement gains in math in recent years and in two states showed spectacular progress, an international survey of student achievement released on Tuesday found. Science performance was flat.
ZImbabwe: The New Zaire
Zimbabwe: Cholera introduced by West from PhysOrg.com
(AP) — The Zimbabwean government on Saturday accused the West of deliberately starting the country’s cholera epidemic, stepping up a war of words with the regime’s critics as the humanitarian crisis deepened.
Researchers finger the cause of ‘gravity fingers’
MIT researchers have found an elegant solution to a sticky scientific problem in basic fluid mechanics: Why water doesn’t soak into soil at an even rate, but instead forms what looks like fingers of fluid flowing downward.
Scientists call these rivulets “gravity fingers,” and the explanation for their formation has to do with the surface tension where the water — or any liquid — meets the soil (or other medium). Knowing how to account for this phenomenon mathematically will have wide-ranging impact on science problems and engineering applications, including the recovery of oil from reservoirs and the sequestration of carbon underground.
The solution, reported in the Dec. 12 issue of Physical Review Letters, involves borrowing a mathematical phrase from the mathematical description of a similar problem — a solution both simple and elegant that had escaped the notice of many researchers in earlier attempts to describe the phenomenon.
Co-authors Luis Cueto-Felgueroso and Ruben Juanes of the MIT Department of Civil and Environmental Engineering discovered the solution while studying the larger question of how water displaces oil in underground reservoirs (petroleum engineers commonly flush oil reservoirs with water to enhance oil recovery).
“Our paper addresses a long-standing issue in soil physics,” said Cueto-Felgueroso. “Lab experiments of water infiltration into homogeneous, dry soil, repeatedly show the presence of preferential flow in the form of fingers. Yet, after several decades, the scientific community has been unable to capture this phenomenon using mathematical models.”
Team led by Purdue professor first to record key event that breaks continents apart
Researchers have captured for the first time a geological event considered key in shaping the Earth’s landscape.
An international research team led by Eric Calais, a Purdue University professor of geophysics, was able to measure ground displacements as two tectonic plates in Africa moved apart and molten rock pushed its way toward the surface during the first so-called “dyking event” ever recorded within the planet’s continental crust.
The event left a wall of magma 6 miles long and 5 feet wide wedged between the two plates. A paper detailing the event will be published Wednesday (Dec. 11) in Nature.
Dyking events have been reported in the thin oceanic crust but had never been directly observed and quantified in the thicker areas of the planet’s shell, Calais said.
“Such dyking events had been included in theories, but researchers had never before been in the right place at the right time with the right equipment to record them,” Calais said. “The event was preceded by a slow slipping of the tectonic plates along a fault line. This also had not been seen before. Faults usually slip suddenly, which produces earthquakes, but this was a very seismically quiet course of events that lasted about one week.”