The diode has a number of applications in electronic circuits. One application you may be familiar with is a rectifier. A rectifier converts alternating current (AC) to direct current (DC). Alternating current periodically changes direction while direct current only flows in one direction. "The most common function of a diode," according to Wikipedia, "is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction)." It’s easy to demonstrate how the diode will let current flow in one direction but block the flow of current in the opposite direction.

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The Obamacare website is not the only thing that debuted incomplete, buggy, difficult to use and nonetheless mandated. The Open Payments Program database, also known as the Physician Payments Sunshine Act, was 12 years in the making and designed to report drug and device industry payments to physicians, but it came onto the scene with a resounding thud, burdensome to most and helping almost no one. But it is too important to dismiss before its shortcomings are addressed, say the authors of a Viewpoint in JAMA.

Psychics, homeopaths, magic soap buyers, anti-vaccine and anti-energy people, they all share one thing in common - no, no, not the same political party (good guess, though!), they embrace organic food.

And if you don't also embrace their giant swath of superstitious crackpottery, they might depart in a huff.

Best to keep it under the covers? Lisa S.

By Sally O'Reilly, The Open University

But what do you want unconsciously? Julien Behal / PA

By Steffen Böhm, University of Essex and Aanka Batta, University of Essex

In the last 20,000 years, Europeans and Asians became numerous and their descendants now comprise the bulk of our 7 billion population. Prior to that, for 130,000 years, the Khoisan (they call themselves Bushmen), of Namibia reigned supreme.

Their lifestyles remain relatively primitive. And genetically, they have not changed all that much either. They number only about 100,000 and a study in Nature Communications compared nearly all the genes of these individuals -- their genomes -- with the genomes of people from around the world, and discovered that the inflow of new genes into the Bushmen has been quite restricted the past 150,000 years.

Polychlorinated biphenyls (PCB) found in flame retardant cloth, paint, adhesives and electrical transformers, have been banned since 1979, but if you live on top of a waste disposal site or you have a 40 year old couch, you could still be exposed to them.

Some new mothers who are breast-feeding (and some who should have stopped by now) have turned to medications to help increase their milk supply - and that meant off-label use of domperidone, a nausea medication, to stimulate breast milk production.

Some studies have suggested it may be related to negative side effects, including irregular heartbeat and sudden cardiac death, but a new article in Journal of Human Lactation,
finds that there is no risk to the babies who drink the milk, though the risks to women may be a concern.   

Your memory can play tricks on you. Shutterstock

By Catherine Loveday, University of Westminster

A new optical technique by which audio information can be extracted from high-speed video recordings, by using an image-matching process based on vibration from sound waves.

The technique is based on the fact that sound waves are mechanical waves that cause air to vibrate when traveling, the paper notes. That vibration through air can cause vibration of objects located in its traveling path, especially if the objects are lightweight, thin, and flexible, such as a piece of paper. The vibrations, although usually with small amplitudes, can be detected and analyzed algorithmically, and audio reconstructed based on those calculations.