An iPhone app that measures pollutants in air

A new smartphone application can now allow users to keep a tab on the air quality and see the level of pollutants around them.

Computer scientists in the University of Southern California hope that as many users as possible download and try it in order to improve the software. Currently, the download works for smartphones running the Android system and soon will be widely available on Android app sources. An iPhone app is in the works.

The basic principle of the Visibility app is simple, according to the paper documenting the work by USC computer science professor Gaurav Sukhatme.

The user takes a picture of the sky while the sun is shining, which can be compared to established models of sky luminance to estimate visibility. Visibility is directly related to the concentration of harmful “haze aerosols,” tiny particles from dust, engine exhaust, mining or other sources in the air. Such aerosols turn the blue of a sunlit clear sky gray.

There is one caveat — It has to be the right picture. The visibility/pollution models are based on the viewing geometry of the image and the position of the sun.

The Visibility app works because modern smartphones contain a rich set of sensors that include cameras, GPS systems, compasses and accelerometers, in addition to the powerful communication capabilities that are inspiring a slew of intelligent phone applications ranging from personal health monitoring to gaming and social networking.

Sameera Poduri, a postdoctoral researcher in Sukhatme’s lab, explained that the accelerometer in the phone — the sensor that tells how the user is holding the phone, determining whether it displays information vertically or horizontally — can “guide the user to point the camera in exactly the right direction.” The picture must be all or mostly sky, which makes a contribution from human user judgment critical. “Several computer vision problems that are extremely challenging to automate are trivially solved by a human. In our system, segmenting sky pixels in an arbitrary image is one such problem. When the user captures an image, we ask him [or her] to select a part of the image that is sky,” noted the research paper.

The accelerometers and the compass on the phone capture its position in three dimensions while the GPS data and time are used to compute the exact position of the sun. The application automatically computes the camera and solar orientation, uploading this data along with the image — a small (100KB) black-and-white file — to a central computer. The central computer analyzes the image to estimate pollutant content and returns a message to the user, as well as registering the information (User identities are anonymized). The system potentially can help fill in the many blanks in the existing maps of air pollution. So far the results are promising, but they indicate that several improvements are possible.

Sukhatme added: “We’re sure we can improve it if we get people trying it and testing it and sending data.”

USB speakers set to get more out of laptops

Soon, music aficionados can use plug-in USB speakers that produce high-quality sound from the laptop without the need for mains power.

The tinny fizz produced by most laptops’ built-in speakers spoils the music quality because the USB port, from which they get their power, can supply only 2.5 watts. Now, the British firm NXT of Cambourne, Cambridgeshire, has come up with a USB-powered system that can deliver up to 15 watts to each speaker, reports New Scientist.

Although power from mains-powered units is held at around 32 volts, a USB 2.0 port can deliver no more than 5.25 volts to a device.

NXT chief executive James Lewis says that most of the time music is quiet enough to be reproduced satisfactorily by circuits running at just 1 volt. So NXT built its USB-powered amplifier to run at low voltage, but able to deliver higher voltages - and more power to the speakers.

This is done by tapping a pair of capacitors that store spare power from the USB during quiet passages. By pre-determining the music signal a couple of milliseconds ahead of the amplifier, the system determines exactly when to raise the voltage and unleash the stored power.

“It’s the first time I’ve heard of using the dynamic reallocation of power for this type of application. It seems like a great idea,” said Andy Dowell, a director of Dolby Laboratories in the U.K. “People would love to get more oomph out of the PC speakers.”

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Depressed? Try trancendental meditation

A new study has revealed that transcendental meditation can successfully be used to treat depression.

The research led by University of California Los Angeles has shown that depressive symptoms almost halved among those who used the therapy over 12 months.

The advocates believe that the meditation reduces stress and increases feelings of calm, sometimes described as "inner peace".

Even patients at risk of depression who had not developed the illness saw benefits. During the study, researchers followed 36 patients with clinical depression, while another, by the University of Hawaii, looked at 112 patients at risk of heart disease, who were also at high risk of suffering from depression.

"These results are encouraging and provide support for testing the efficacy of Transcendental Meditation in the treatment of clinical depression," telegraph.co.uk quoted Hector Myers, the co-author of one of the studies and professor and director of Clinical Training in the Department of Psychology at the University of California Los Angeles (UCLA), as saying.

Both studies compared the groups with healthy people who were also asked to perform Transcendental Medication over the course of a year. They show that patients experienced the benefits of meditation rapidly.

The findings revealed that those with depression reported that their symptoms had nearly halved within three months of starting the treatment, and the effects were maintained across the rest of the year-long study.

Similarly, in the patients at risk of developing heart disease, the full benefits were seen within three months, over the course of which time depressive symptoms fell by around a third.