JON CARTWRIGHT – Page 36 – & THREE QUARKS EDITORIAL

Why All Faucet Drips Have the Same Shape

ScienceJon Cartwright13 July, 2012

Published in Science, 13 Jul 2012

To some, the “drip, drip” of a leaky faucet is a minor irritation; to physicists, it’s a great example of the predictive powers of science. In 1996, theoretical work suggested that, as a water drop hangs from a faucet, its cone-shaped neck should always have the same internal angle at break-off: 36.2°. That was an ambitious prediction given the hugely complex dynamics of dripping water, but it was also very difficult to test with any accuracy. Now, thanks to modern technology, researchers have finally plugged all doubts. […]

The rest of this article is available here.

Cornstarch Physics Is Shear Nonsense

ScienceJon Cartwright11 July, 2012

Published in Science, 11 Jul 2012

Filling a small swimming pool with cornstarch and water has long been a physicist’s party trick. Step onto it slowly and you’ll sink but run across quickly and the oozy mixture will support your weight—almost as though it has turned from liquid to solid. Several reasons have been offered for the phenomenon, but now researchers believe they have the real answer.

Mixtures of cornstarch, water, and other suspensions have been known as “shear-thickening” materials. Shear is the type of stress that exists when particles slide over one another, and scientists thought that if the shear stress in a cornstarch suspension exceeded a certain threshold, the thickness or viscosity would increase massively—enough to support a person’s weight. […]

The rest of this article is available here.

Waves of migration could help heal tissue

Physics WorldJon Cartwright11 July, 2012

Published in Physics World, 11 Jul 2012

Researchers in Spain and the US have discovered that ultraslow waves occur during the expansion of living tissue. These waves could explain how cells migrate to the right places for an organism to grow, repair itself or develop tumours.

Growth, repair and the development of tumours are all processes that involve the expansion of a monolayer of cells, or “epithelial expansion”. If you have a small wound, for example, the wound will form a scab and, beneath that, a matrix for the construction of new tissue. But in the final stage, a monolayer of cells will migrate from undamaged tissue to form a new outer-boundary layer. […]

The rest of this article is available here.

Dark-matter filament spotted

Physics WorldJon Cartwright6 July, 2012

Published in Physics World, 6 Jul 2012

Physicists claim to have reliably detected a mammoth filament of dark matter stretching between two galaxy clusters, for the first time. If the detection is bona fide, it could be one of the best confirmations yet of the “standard model” of the universe’s evolution, the so-called lambda cold-dark-matter (?CDM) model.

The ?CDM model posits that, in the early universe, dark matter was spread out in a web of filaments. Over time, this cosmic web would have helped all the normal “baryonic” matter to clump together, particularly in the regions where its filaments intersected. Today, we see the result of this clumping at the filament intersections: galaxy clusters and, on a smaller scale, individual galaxies and stars. […]

The rest of this article is available here.

SKA’s double site splits opinion

Physics WorldJon Cartwright1 July, 2012

Published in Physics World, 1 Jul 2012

The decision to build the world’s biggest radio telescope – the Square Kilometre Array – on two separate sites in Africa and Australasia has been praised by many. Jon Cartwright examines whether dual sites will hamper science prospects

Two sites are better than one: that is the consensus among the five voting members of the SKA Organisation on the location of the world’s biggest radio telescope. Before the votes were cast on 25 May, the widespread expectation had been that the Square Kilometre Array (SKA) would be hosted in either Africa or in Australasia. As it turned out, the voters plumped for both.

Double the site, double the prides left intact. After an escalating bidding war that has lasted almost a decade, neither Africa nor Australasia will be able to boast a lion’s share of the 71.5bn telescope. Come 2024, when the telescope is slated for completion, Africa will host most of the mid-frequency dishes, which provide high sensitivity, while Australasia will host the equally important low-frequency antennas, which provide a broad field of view. But some observers have been left wondering if it will be possible to have a dual site without subtracting from SKA’s design goals.

“I am troubled by this decision to split the bid,” says Dale Frail, an astronomer at the US’s National Radio Astronomy Observatory (NRAO) in Socorro. Frail, who is not associated with the SKA Organisation, refers to the “first photon” problem, namely that a big chunk of any observatory’s construction budget must be spent on site-specific infrastructure and personnel before the first data can be collected. “So the issue for me is that SKA will now split this infrastructure cost among two sites,” he says. “As there is a finite amount of money, I fear that the remaining dollars will just build less scientific capability.” […]

For the rest of this article, please contact Jon Cartwright for a pdf.

Gigapixel camera pushes resolution limit

Physics WorldJon Cartwright20 June, 2012

Published in Physics World, 20 Jun 2012

Researchers in the US have unveiled a 1 gigapixel camera, which has about five times as many pixels as today’s best professional digital cameras and nearly 100 times as many as a compact consumer camera. Moreover, the camera has a much smaller aperture than other gigapixel devices – meaning that, unlike other sensors, this latest camera pushes the fundamental resolution limit of optical devices. The team has also shown how the device could be used in several applications including surveillance, astronomy and environmental monitoring.

In the past, gigapixel images have be formed by stitching together 1000 or more megapixel images, or by scanning a sensor across a large-format image. Acquiring “snapshot” gigapixel images is trickier, but a few options exist or are in development. One of these is the 3.2 gigapixel digital camera that will sit within the Large Synoptic Survey Telescope (LSST), an optical device currently under construction in northern Chile. […]

The rest of this article is available here.

Electrode dip to freshen up saltwater

Chemistry WorldJon Cartwright10 June, 2012

Published in Chemistry World, 10 Jun 2012

Producing freshwater from brackish water could be cheaper and easier than previously thought, according to researchers who have developed a new technique for desalination. The process, which is a refinement of a well-known method called capacitive deionisation, could treat large volumes of water in a continuous ‘merry-go-round’ of carbon electrodes.

Likun Pan, a physicist at the East China Normal University in Shanghai who was not involved with the research, calls the technique a ‘radical departure’ for capacitive deionisation, the working principle of which dates back to the 1960s. ‘This [study] will be followed up by many groups in the world, I am sure, as it is so simple to do it in this way,’ he says. […]

The rest of this article is available here.

Unraveling the Mystery of Self-Planting Seeds

ScienceJon Cartwright6 June, 2012

Published in Science, 6 Jun 2012

The rest of this article is available here.

ScienceShot: Unraveling the Mystery of Self-Planting Seeds

ScienceJon Cartwright6 June, 2012

Published in ScienceNOW, 6 Jun 2012

When it comes to sowing seeds, some plants only have to drop them and let gravity take care of the rest. But seeds from a family of small flowering plants known as Geraniaceae, give themselves a helping hand: after bursting open from beak-shaped fruits, they literally drill themselves into the ground. Scientists have long known that this bursting and drilling results from hairy appendages on the seeds called awns, which coil up and straighten out with changes in humidity, slowly propelling the seeds downward. Now, researchers have figured out the structural changes occurring in the cells of these awns that generates the coiling mechanism. […]

The rest of this article is available here.

‘Schrödinger’s hat’ could spy on quantum particles

Physics WorldJon Cartwright4 June, 2012

Published in Physics World, 4 Jun 2012

An international team of physicists has proposed a new device that could detect the presence of waves or particles while barely disturbing them. Called a “Schrödinger’s hat”, the device has not yet been built in the lab but the team believes that it could someday be used as a new type of sensor for quantum-information systems.

In the microscopic world of quantum mechanics, direct observation of the property of a particle – the position of an electron, for example – causes the collapse of the particle’s wavefunction. The result is that the particle that you set out to measure has been changed in a significant way. […]

The rest of this article is available here.