Earth-size planets abound in Milky Way: study - AFP

Earth-size planets abound in Milky Way: study(AFP) – 1 hour ago

WASHINGTON — One out of four Sun-like stars in our Milky Way galaxy could host Earth-size planets, making life-bearing systems like ours possibly more common than previously thought, according to a new astronomical study.

Dubbed the most extensive planetary census of its kind, the NASA-funded study at the University of California, Berkeley found that smaller planets rather than massive ones are prevalent in close orbit to the stars.

"The data tell us that our galaxy, with its roughly 200 billion stars, has at least 46 billion Earth-size planets, and that's not counting Earth-size planets that orbit farther away from their stars in the habitable zone," said study co-author Geoff Marcy.

The astronomers for five years used the W.M. Keck Observatory in Hawaii to search 166 sun-like stars near our solar system for planets ranging from three to 1,000 times the mass of Earth.

The results showed more small planets than large ones.

"We studied planets of many masses -- like counting boulders, rocks and pebbles in a canyon -- and found more rocks than boulders, and more pebbles than rocks," said UC Berkeley's Andrew Howard, lead author of the study that will be published in Friday's issue of the journal Science.

"Our ground-based technology can't see the grains of sand, the Earth-size planets, but we can estimate their numbers," he said.

"Earth-size planets in our galaxy are like grains of sand sprinkled on a beach -- they are everywhere," he added.

The study suggests that potentially habitable planets like Earth could also be common in the Milky Way.

These smaller planes would orbit farther away from their stars, where temperatures could be favorable for life.

A similar survey of our galaxy is being conducted by the National Aeronautics and Space Administration's Kepler spacecraft, which is expected to find the first true Earth-like planets in the next few years.

In the UC Berkeley survey, about 6.5 percent of stars held intermediate-mass planets, with 10 to 30 times the mass of Earth, similar to Neptune and Uranus.

Another 11.8 percent had the so-called "super-Earths," weighing in at only three to 10 times the mass of Earth.

The astronomers extrapolated from these survey data to estimate that 23 percent of sun-like stars in our galaxy host even smaller planets, the Earth-sized ones.

Copyright © 2010 AFP. All rights reserved. More »

View the original article here

Biodiversity study sounds an extinction alert (for things with spines) - Christian Science Monitor

If a creature has a spine and walks, flies, swims, or crawls, it may be in serious trouble.

Skip to next paragraph

Some 20 percent of all vertebrate species on Earth are threatened by extinction, according to a newly published survey – a study the research team involved says is the most exhaustive to date on biodiversity among vertebrates.

The losses are due largely to human encroachment on habitat, over-fishing and over-hunting, as well as the arrival of invasive species in habitats whose natural inhabitants have no defenses against the invaders, the study says.

But within an admittedly bleak global picture, the researchers add, conservation efforts have halted the decline in some species and brought others a significant step closer to recovery.

"The bad news can be extremely disheartening," says Ana Rodrigues, a scientist with the Center for Functional and Evolutionary Ecology in Paris and one of a team of 174 scientists from 38 countries who co-authored the study.

"But our results show that conservation efforts are not wasted," she adds.

Biodiversity refers to the variety of plant and animal species in an ecosystem. Generally the greater the diversity, the more resilient the ecosystem is to disturbances, either natural or man-made.

Using an internationally recognized "red list" index that tries to capture changes in a species' population size, structure, and geographic range, among other factors, the team found that without conservation programs, biodiversity among birds and mammals would have declined an additional 18 percent over the past 30 years. The programs range from efforts to establish safe havens such as marine protected areas or wildlife reserves to campaigns to battle invasive species.

The report draws on research conducted by some 3,000 scientists worldwide. It was published Tuesday on the journal Science’s website as delegates from 194 countries were meeting in Nagoya, Japan, to try to set conservation targets for the next decade under the UN's Convention on Biological Diversity, which is scheduled to end Oct. 29.

Eight years ago, parties to the convention agreed to significantly reduce the rate of biodiversity loss by 2010. But in April, a study published online in Science showed that the rate of decline in biodiversity across a broad range of plants and animals was not slowing. Countries had failed to meet the 2010 goal.

Page: 1 | 2

View the original article here

Hormone therapy raises breast cancer deaths: study - Reuters

By Julie Steenhuysen

CHICAGO | Tue Oct 19, 2010 5:08pm EDT

CHICAGO (Reuters) - Women who took hormone replacement pills had more advanced breast cancers and were more likely to die from them than women who took a dummy pill, raising new concerns about the commonly prescribed drugs, U.S. researchers said on Tuesday.

The study, published in the Journal of the American Medical Association, is the first to report more breast cancer deaths among women taking hormone replacement therapy.

And it contradicts prior studies that suggest women taking the drugs had less aggressive, easier-to-treat breast cancers.

"As opposed to the prevailing thought of two years ago, that cancers associated with estrogen plus progesterone would be favorable and not much of a problem, we are actually showing they are associated with an increased risk of death from breast cancer," Dr. Rowan Chlebowski of the Los Angeles Biomedical Research Institute, who led the study, said in a telephone interview.

The findings include 11 years of follow-up from the Women's Health Initiative study, which in 2002 found women who took estrogen plus progesterone for five years had higher rates of ovarian cancer, breast cancer, strokes and other health problems.

Sales of U.S. market leader Wyeth's combined estrogen plus progesterone pill Prempro have fallen by about 50 percent since 2001 to around $1 billion a year. Wyeth is now owned by Pfizer.

TWICE AS MANY CANCER DEATHS

Chlebowski's team analyzed data on the more than 12,000 women in the study. They found twice as many taking HRT died from breast cancer -- 2.6 per 10,000 per year versus 1.3 per 10,000 women per year -- compared to women who took a placebo.

Nearly 24 percent of the breast cancer patients who took HRT had tumors that had spread to the lymph notes, compared with 16 percent of women taking placebos.

"All the scary cancers with unfavorable prognoses were also increased," Chlebowski said, citing increases in aggressive forms of breast cancer, and not just estrogen-fed cancers that are easier to treat.

"And then for the first time we show deaths from breast cancer are significantly increased as well," he said.

Pfizer said in a statement the company stands behind Prempro's current labeling, which advises doctors to prescribe the drug at the lowest effective dose for the shortest possible period of time.

But even that may be risky, suggests Dr. Peter Bach of Memorial Sloan-Kettering Cancer Center in New York, who wrote a commentary in the same journal.

Doctors can only be guessing that taking the pills at a lower dose and for a shorter time would be less harmful, Bach said in a telephone interview.

Doctors "should be aware that this approach has not been proven in rigorous clinical trials," Bach wrote.

*We welcome comments that advance the story directly or with relevant tangential information. We try to block comments that use offensive language or appear to be spam and review comments frequently to ensure they meet our standards. If you see a comment that you believe is irrelevant or inappropriate, you can flag it to our editors by using the report abuse links. Views expressed in the comments do not represent those of Reuters.

View the original article here