Thursday, February 24, 2011

Urban Supersprawl

photograph by Pablo Lopez Luz

Mexico City, Mexico
Some 20 million people live in Mexico City, the world's fifth largest metropolitan area. In 1800 the urban fraction of the global population was 3 percent. Today it is 50 percent and rising. In crowded shantytowns, the need for clean water and sanitation is urgent. But urbanization has an upside: Per capita, cities use less energy and pollute less than rural areas.

Saturday, February 19, 2011

"Horror" Virus

Image courtesy Jonathan Heras, Equinox Graphics

In a 3-D image, a bacteriophage aggressively attacks a bacterium "B-movie horror style," according to creator Jonathan Heras of Equinox Graphics, Ltd. The digital ambush snagged an honorable mention in the illustrations category of the 2010 International Science and Engineering Visualization Challenge.

Bacteriophages are viruses with "alien, spindly legs" and sucker-shaped mouths used to "relentlessly pursue their prey," Heras said in a statement. The viruses hijack bacteria's biology and use the victims as virus "replication factories," he said.

Overall, the 2010 entries were "exceptional," communicating science "in a way that the public can understand and appreciate," Monica M. Bradford, Science's executive editor, said in a statement.

"The international competition highlights the innovation and technical expertise of scientists who are able to visually attract a wide audience and engage them to experience the complex nature and beauty of science."

HIV in 3-D

Image courtesy Konstantinov/Stefanov/Kovalevsky/Voronin, Visual Science Company

The most detailed 3-D model yet of the HIV virus won first place for illustrations in the 2010 International Science and Engineering Visualization Challenge.

Sponsored jointly by the journal Science and the National Science Foundation, the annual competition awards entries that "engage people worldwide and convey science close up in novel and visually stimulating ways," according to a statement. Judging criteria include visual impact, effective communication, freshness, and originality. (See some of the 2009 winners.)

A Russian team led by Ivan Konstantinov analyzed data from more than a hundred scientific journals to digitally depict HIV as close to the real thing as possible. The two-tone color scheme shows HIV (orange) attacking and fusing with an immune cell (gray). The triangular cut-away shows how the virus integrates itself to turn the cell into a virus factory. (Get the facts on AIDS.)

"We consider such 3-D models as a new way to present and promote scientific data about ubiquitous human viruses," Konstantinov, of the Visual Science Company, said in a statement.

Thursday, February 17, 2011

Reading Comprehensive

What causes weather?

Weather is the physical condition of the atmosphere at a particular time. It includes temperature, air pressure and water content.

Weather is produced when air moves from plece to place. This moving air is known as wind. Winds are caused by warm air rising and cooler air mooving to replace it. Warm air is usually less dense then cooler air; therefore, it creates low air pressure. Cool air is more dense and creates high air pressure.

Usually we have fine the weather when the air pressure is high, and we will have clouds, rain or snow when air pressure drops.

1. What is the purpose ot the text?

a. To retell abou weather

b. To explain the process of the information of weather

c. To describe the steps of the information of weather

d. To describe about weather

e. To persuade people about the information of weather

2. When do we find good weather?a. When air moves from place to place

b. When there is moving air

c. When warm air is less dense than cool air

d. Ahen air pressure drops

e. When the air pressure is high

3. The following statements are true except...

a. A physical condition of the atmosphere at a particular time is called weather.

b. Air movement from place to place causes weather.

c. The moving air is called wind.

d. Warm air is usually more dense than cool air.

e. When air pressure drops we usually have clouds.

4. “Cool air is more dense and creates high air pressure.” The synonym of the underline word is...

a. compact

b. solid

c. slow

d. low

e. crowded

Wednesday, February 16, 2011

Scarabaeus sacer

Scarabaeus sacer
is a species of dung beetle, found in coastal dunes and marshes around the Mediterranean Basin. It collects balls of dung which it rolls to an underground chamber to feed its offspring. This behaviour inspired the Ancient Egyptians to compare it to the sun god Khepri, and they considered S. sacer to be sacred.

Scarabaeus sacer is found across North Africa, southern Europe and parts of Asia. In the Camargue, S. sacer is almost exclusively a coastal species, living only in dunes and coastal marshes. It serves as the host for the phoretic mite Macrocheles saceri.
The head of S. sacer has a distinctive array of six projections, resembling rays.
Like other dung beetles, S. sacer has no tarsi (usually the final segment of the insect leg) on its front legs, which are specialised for forming a ball of dung. The ball of dung is transported to a underground chamber, and is used to feed the beetle's larvae.

Scarabaeus sacer is the most famous of the scarab beetles. To the Ancient Egyptians, S. sacer was a symbol of Khepri, the early morning manifestation of the sun god Ra, from an analogy between the beetle's behaviour of rolling a ball of dung across the ground and Khepri's task of rolling the sun across the sky.
The Egyptians also observed young beetles emerging from the ball of dung, from which they mistakenly inferred that the female beetle was able to reproduce without needing a male. From this, they drew parallels with their god Atum, who also begat children alone.
Scarabaeus sacer was the species which first piqued the interest of William Sharp Macleay and drew him into a career in entomology.

Scarabaeus sacer was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, the starting point of zoological nomenclature. It has since been treated by "the vast majority of authors" as the type species of the genus Scarabaeus, even though strict application of the International Code of Zoological Nomenclature would require Scarabaeus hercules (now usually called Dynastes hercules) to be the type species, following Pierre André Latreille's 1810 type designation.

Friday, February 11, 2011

Supersemar Scholarship

For all my friends who want to apply Supersemar Scholarship from Supersemar Foundation in State Islamic University Sunan Kalijaga Yogyakarta. You can download the application by the link bellow

Dok.Beasiswa Supersemar 2011.doc

Saturday, February 05, 2011

Portuguese Man-of-War

Photograph by Jennifer Kiewit, Your Shot

Often mistaken for a jellyfish, the Portuguese man-of-war is actually made up of a colony of organisms working together. Its tentacles can extend 165 feet (50 meters) below the surface, although 30 feet (10 meters) is more the average.

Friday, February 04, 2011

Six New Planets: Mini-Neptunes Found Around Sunlike Star

"This is the most closely packed known planetary system," expert says.

Jupiter, Earth, and planets found by the Kepler telescope, including the newest (bottom row).
Diagram courtesy Tim Pyle, NASA

Victoria Jaggard

NASA's Kepler space telescope has uncovered six new planets huddled around a sunlike star—odd worlds that astronomers have dubbed mini-Neptunes, scientists announced Wednesday.
Five of the new planets are closer to their parent star than Mercury is to the sun. The sixth world lies farther out, within a region that would fit inside the orbit of Venus.
"This is the most closely packed known planetary system," said study co-author Jonathan Fortney, an astronomer with the Lick Observatory at the University of California, Santa Cruz.
The planets are relatively small—ranging from roughly 2 to 4.5 times Earth's radius—but they are also surprisingly lightweight, indicating they are made mostly of gases. Based on their densities, four of the planets appear to have thick atmospheres of hydrogen and helium.
The two planets closest to the star have higher densities, suggesting these bodies have atmospheres of mostly water, with just a thin skin of hydrogen and helium.
Finding so many planets around the same star and being able to calculate their properties is a scientific boon, Fortney said. Like paleontologists studying related dinosaur species, astronomers can look at multiple worlds that were born together to get a better understanding of planetary transformations.
"We can do comparative science and ... we can think about how the evolution of the planets has diverged over time," he said.

New Planets Found Via Orbital Dance

The Kepler space telescope was designed to look for Earth-size planets that transit—or pass in front of—their host stars, as seen from Earth.
"We're basically targeting 100,000 to 150,000 stars next to the constellation Cygnus," said Fortney, who is a member of the Kepler science team. "Kepler just stares at that patch of sky unblinking for four years."
With enough time, astronomers can tease out periodic dips in the light from stars as planets pass. (Find out how you can help hunt for planets using Kepler.)
Fortney and colleagues found six signature dips in light from a star called Kepler-11, about 2,000 light-years away. The star is almost the same size, temperature, and brightness as our sun: "It's very much like a solar twin," Fortney said.
At such a distance, though, the star is very dim, making it hard for astronomers to use other planet-hunting techniques to verify the find. Instead the Kepler team confirmed the discoveries using a method called transit timing variations, or TTV.
"Think about one planet that transits," Fortney said. "If its orbital period is ten days, every ten days it will pass in front of the parent star. But if multiple planets transit, they'll affect each other [via gravity]. A planet may transit early or late."
Similar calculations of planets affecting each other's orbital timing are what allowed French and German astronomers to find Neptune in 1846.
The outermost planet in our solar system, Neptune was barely visible to telescopes of the time, and those who could see it thought it was a star. But astronomers knew that Uranus wasn't orbiting as it should, based on laws of physical motion.
Uranus's odd orbit led mathematician Urbain Joseph Le Verrier to predict Neptune's position and mass to account for the discrepancies.
In the case of the Kepler-11 star, the gravity-driven choreography of dips in starlight is almost certainly the product of multiple planets, the team concluded. Further studies, detailed this week in the journal Nature, allowed astronomers to calculate with significant accuracy the masses, positions, sizes, and densities of five of the new worlds.
The sixth planet is far enough away from its siblings that it doesn't affect their orbital dance. Instead astronomers had to run through a suite of calculations to be sure the planet exists. While the team is confident it's there, they weren't able to tease out as many details about the outlying world.
"We know the radius is about 3.6 times that of Earth," Fortney said, "and it's probably less than 30 Earth masses."

"Super Earth" Among New Planets?

The new planetary sextet is remarkably similar to another tight-knit set of worlds found around the sunlike star HD 10180, which was announced last fall. That star lies a mere 127 light-years from Earth.
A team of scientists based in Europe found five Neptune-like worlds close to the star and a larger sixth planet farther out.
They also saw a faint signature of a much smaller world very close to the star that may be a "super Earth"—a rocky planet much larger than our own.
One key difference between the two newfound systems is that "the 'packing' is much more pronounced in the new Kepler system," HD 10180 study leader Christophe Lovis, an astronomer with the Observatory of Geneva in Switzerland, said in an email.
"At first glance I was very surprised that such a system could be dynamically stable on the long term," he said. "Planet masses in the Kepler system are lower than in HD 10180 ... which probably makes it possible to have an even more compact configuration."
Lovis and colleagues had found the planets around HD 10180 using the High Accuracy Radial velocity Planet Searcher, or HARPS, instrument in Chile. The radial-velocity method measures wobbles in starlight caused by the gravitational tugs of orbiting bodies.
"The fact that HARPS and Kepler, using different techniques, find similar things is reassuring in itself and shows how complementary both approaches can be."
Lovis notes, however, that he'd prefer to have the planetary properties of the Kepler-11 system confirmed by other techniques.
"In this particular case, radial velocities would be helpful to measure the masses, probably more precisely than is feasible with TTV," he said. The problem is that the Kepler-11 star "is almost too faint for precise radial velocity followup and would require a lot of telescope time.
"This will remain the main contrast between the Kepler survey and a typical radial velocity survey like the HARPS one: Kepler looks at tens of thousands of distant stars, whereas HARPS looks at a few hundred nearby, bright stars."

Even More New Planets Waiting for Discovery?

For now astronomers aren't sure whether the Kepler-11 system hosts any rocky Earthlike worlds like the one circling HD 10180.
"It's possible that there are smaller planets that we haven't been able to see yet," said Fortney, co-author of the new Kepler study.
"With a few more years of data, one may emerge. It's also possible that TTV will show us there's another planet in the system that doesn't transit. ... "
What the existing data do reveal is that the closely orbiting group around Kepler-11 most likely formed very quickly.
"The way we think that big gas giants like Jupiter form is that first a protocore of ice and rock forms that's like ten [times Earth's mass]. Through its gravity, the core pulls tremendous amounts of gases on top"—notably hydrogen—Fortney said.
In the disk of planet-forming materials, free hydrogen gas lasts just five million years or so before stellar wind—charged particles flowing from the host star—blows it all away. That means the gassy planets around Kepler-11 must have grown up quickly for them to be full of hydrogen.
The Kepler-11 system is also a good case study for what happens to gas planets that move in close to their stars. Based on their sizes and orbital dynamics, the Kepler planets formed farther from the star and migrated inward, the team thinks.
The two mini-Neptunes closest to the star may once have had thicker hydrogen-helium atmospheres like their siblings, but as the two nearer worlds cuddled close to the star, its powerful radiation began to strip away the outer layers.
Looking at the differences between the two sets of planets can help astronomers understand exactly how such worlds lose mass over time.
"In the long term, I think we're going to find that multiplanet systems are common," Fortney added. "With transits limited to seeing edge-on systems, we're always going to be finding the minimum number of planets—a system could have an alignment so that we measure three planets when really there are five."
But overall, he said, "when you see one planet, you're probably going to find another."