CT scan on kids triples cancer risk

Kounteya Sinha, TNN | Jun 7, 2012, 04.18AM IST

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A patient undergoing CT scan.

Children subjected to CT scans with high radiation doses face a three time increased risk of suffering from leukaemia and brain cancerduring their lifetime.

In the most conclusive evidence till date, a study published in British medical journal Lancet on Wednesday says radiation exposure received from two to three CT scans of the head in childhood (aged under 15 years) — giving a cumulative dose of around 60 milli-Grays (mGy) can triple the risk of later developing brain cancer.

On the other hand, around 5 to 10 such scans (cumulative dose around 50 mGy) could triple the risk of developing leukemia.

The authors from the Newcastle University studied around 180,000 patients who underwent a CT scan between 1985 and 2002 from 70% of the UK's hospitals.

These data were then linked to cancer incidence and mortality reports in the UK National Health Service Registry between 1985 and 2008.

From this, they calculated excess incidence of leukemia and brain tumours. The dose of radiation received by the brain and bone marrow varied by age and body part scanned. A total of 74 from 178,604 patients were diagnosed with leukemia and 135 of 176,587 were diagnosed with brain cancer.

The authors say that, of every 10,000 people between the ages of 0-20 years receiving 10 mGy from a CT scan, there would be about one expected excess leukemia case, whereas there were would be one excess case of brain cancer for every 30,000 people. Applying the dose estimates for one head CT scan before the age of 10 years, this would translate into approximately one excess case of leukaemia and one excess brain tumour per 10,000 patients in the decade after the first exposure.

New Internet standard gives global network room to grow

1:36 am | Thursday, June 7th, 2012

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A new standard called IPv6—which came into effect on Wednesday, June 6, 2012, allows for trillions of "IP" numbers or addresses, up from the current 4.3 billion. US equipment maker Cisco is projecting that by 2016, there will be nearly 18.9 billion network connections, or nearly 2.5 connections for each person on earth, compared with 10.3 billion in 2011. AP PHOTO/ROGELIO V. SOLIS

WASHINGTON—A new Internet standard giving the global network more room to grow came into effect Wednesday, a move that users probably won’t notice.

The switch occurred at 0001 GMT Wednesday, when Internet operators switched to a new standard called IPv6 that allows for trillions of “IP” numbers or addresses, up from the current 4.3 billion.

“To ensure the Internet can continue to grow and connect billions more people and devices around the world, thousands of companies and millions of websites have now permanently enabled the next generation of Internet Protocol (IPv6) for their products and services,” the Internet Society, an advisory panel, said.

“Participants in World IPv6 Launch include the four most visited websites in the world – Google, Facebook, YouTube, and Yahoo! – as well as home router manufacturers and Internet Service Providers in more than 100 countries. By making IPv6 the ‘new normal,’ these companies are enabling millions of end users to enjoy its benefits without having to do anything themselves.”

Vint Cerf, one of the inventors of the Internet standard, who is now the “chief Internet evangelist” at Google, said the change gives the Internet room to grow.

“When the Internet launched operationally in 1983, its creators never dreamed that there might be billions of devices and users trying to get online,” he said.

“Yet now, almost three decades later, that same Internet serves nearly 2.5 billion people and 11 billion devices across the globe. And we’re running out of space.”

Some analysts say there may be annoyances for people using older equipment, because the “path” to websites using compatible equipment may be different.

But Johannes Ullrich of the SANS Technology Institute said the transition appeared to be going smoothly.

“So far, there are no big issues with the IPv6 transition,” he told AFP.

He said many Internet operators are using a method known as “Happy Eyeballs,” which allows traffic to be routed over IPv6 or the older IPv4 equipment depending on which is more efficient.

The technology firm Nominum surveyed 67 major Internet service providers in North America, Japan, Europe and Latin America and found that 97 percent of them have either already implemented or plan to implement IPv6.

“European ISPs appear to have the greatest risk of not making the transition in time since under current policies the Regional Internet Registry for Europe is projected to run out of IPv4 addresses later this year,” Nominum said.

The full transition will take several years, and old IPv4 devices and networks should continue to function as before.

Each piece of hardware – including home computers, tablets and mobile devices – has a unique IP address to connect to the Web.

With about seven billion people on the planet, the IPv4 protocol doesn’t allow for everyone to have a gadget with its own online address.

The situation has been equated to not having enough telephone numbers for every user.

If there are not enough addresses, neighbors will have to start sharing IP addresses, which can slow things down.

Over time, home Internet users will need to switch devices such as routers and modems to be compatible with the new system. But Internet service providers have been preparing and say current equipment will function as before.

US equipment maker Cisco is projecting that by 2016, there will be nearly 18.9 billion network connections, or nearly 2.5 connections for each person on earth, compared with 10.3 billion in 2011.

Portrait of a Black Hole

By adapting a global network of telescopes, astronomers will soon get their first look ever at the dark silhouette of a black hole

By Avery E. Broderick and Abraham Loeb | November 25, 2009 | 16

Menacingly dark disk of the Milky Way galaxy's central black hole, and the hot gas caught in its gravity, could look like this computer simulation when a network of radio telescopes begins observing next year. Interstellar gas will, however, blur the finer details.Image: Courtesy of Avery E. Broderick

In Brief

Black holes are among the most mysterious objects in the universe. So far astronomers have observed them only indirectly, from their gravitational effects on stars and from the radiation emitted by hot gas spiraling toward them.
Astronomers are adapting a network of radio telescopes to produce images of the supermassive black holes that lie at the center of the Milky Way and M87 galaxies.
Better studies of black holes not only would help explain unusual phenomena produced by the holes but also could test Einstein’s theory of general relativity and provide vital insights into the nature of gravity in extreme situations.

You have probably seen the TV commercial in which a cell phone technician travels to remote places and asks on his phone, “Can you hear me now?” Imagine this technician traveling to the center of our Milky Way galaxy, wherein lurks a massive black hole, Sagittarius A* (Sgr A*), weighing as much as 4.5 million suns. As the technician approached within 10 million kilometers of the black hole, we would hear his cadence slow down and his voice deepen and fade, eventually turning to a monotone whisper with diminishing reception. If we were to look, we would see his image turn increasingly red and dim as he became frozen in time near the black hole’s boundary, known as the event horizon.

The technician himself, however, would experience no slowing of time and would see nothing strange at the location of the event horizon. He would know he had crossed the horizon only when he heard us say, “No, we cannot hear you very well!” He would have no way of sharing his last impressions with us—nothing, not even light, can escape from gravity’s extreme pull inside the event horizon. A minute after he crossed the horizon, the gravitational forces deep inside the hole would tear him apart.