Tests for Alzheimer's disease can usually only pick it up once brain damage has already occurred. But now

could lead to early diagnosis because a key biomarker for the disease can be identified in the retina and lens of the eye. Two different techniques of using substances to show signs of beta-amyloid in the eye had a high rate of success in correctly determining which members of a set of volunteers did or did not have the disease as later verified by PET scans. That'll be good news for many people.

WHITE ON WHITE: Many parts of the Arctic are remote and inaccessible, which makes studying wildlife such as polar bears very hard indeed. US researchers though have discovered that satellite images can help them gather information about the mammals almost as accurately as ground surveys, but at lower cost. Biologists at the University of Minnesota used satellites to capture images of polar bears in Foxe Basin, Nunavut, in the Canadian Arctic. Their images counted a similar number of bears to those counted in an aerial survey. One problem though is that aerial surveys are better able to show demographics such as family groups and cubs. Another challenge is that the researchers need better ways to analyse the satellite images. So there's a problem for the mathematicians out there.


THE OTHER HALF: O3b Networks is busy placing broadband satellites into an unusual medium Earth orbit at an altitude of 8,062 kilometres. Four more were launched just the other day. The relatively low orbit reduces the latency involved in sending signals to and from satellites. The O3b satellites are intended to bring broadband communications to the "other three billion" people on the planet who currently have no connection at all or remain underserved, including parts of Africa, Latin America, the Middle East, Asia and the Pacific Ocean Islands, including the Cook Islands. The satellites provide coverage within 45 degrees of latitude north and south of the equator. Half the planet is a huge goal.

GET OUT THE LEAD SUIT: Worried about or just interested in the radiation all around you? The MiniSpec radiation detector is for you. It's smaller than a golf ball, portable and inexpensive, yet more efficient and accurate than many existing technologies that cost far more. The system is a miniaturised gamma ray spectrometer, which means it can measure not only the intensity of radiation but also identify the type of radionuclide that is creating it. You may have heard about Geiger counters — this is much more sophisticated. The device has WiFi so it can be connected to the Internet, or used remotely. Unfortunately development hasn't finished yet, so the MiniSpec isn't yet available commercially. There are endless possibilities here for those who promote products based on health scares.

HIT NO MISS: The .50-caliber self-guiding EXACTO bullet from DARPA finds its own way to its target. The rounds hit targets that are offset from where the sniper rifle is aimed by manoeuvring in flight to compensate for weather, wind, target movement and other factors that could impede successful hits. How long before big game hunters get their hands on this kind of technology?

Miraz Jordan,