If you live in an area where solar power is close to viable, you probably also do not get a lot of rain. Over time, dust and dirt build up on solar panels, leading to a loss of efficiency.

But not enough to warrant washing them, according to an analysis by the University of California, San Diego. 

In the beginning, there are embryonic stem cells, which divide and increasingly differentiate as they do so. The ensuing tissue cells remain in a stable state, a skin cell does not spontaneously change into a nerve cell or heart muscle cell.

The applications for embryonic stem cells
are many: When nerve tissue becomes diseased, for example, then doctors could take healthy cells from the patient's own skin. They could then reprogram these to develop into nerve cells. These healthy nerve cells would then be implanted into the diseased tissue or even replace it entirely. This would treat, and ideally heal, diseases such as Parkinson's disease. 

Up to 20 percent of infertile couples in America have unknown reasons for their infertility but researchers led by Catherine Racowsky, PhD, director of the Assisted Reproductive Technologies Laboratory at Brigham and Women's Hospital, wants to fill in that blank, and hints that it could be exposure to Bisphenol-A (BPA). 

Oxytocin, called the 'love hormone' in popular accounts, affects men and women differently in social contexts, say a group of psychologists. In men it improves the ability to identify competitive relationships whereas in women it facilitates the ability to identify kinship.

Oxytocin is released in our bodies in various social situations. Our bodies release it at highwe levels during positive social interactions such as falling in love, experiencing an orgasm or giving birth and breastfeeding and in previous papers, 
Prof. Simone Shamay-Tsoory from the Dept. of Psychology at the University of Haifa

Raising fish in tanks  doesn't help them all that much when they are released into the wild - but there may be an easy fix: put in hiding places and obstacles. It makes fish smarter and improves their chances of survival in nature, according to a new paper.

Why does that matter? Because conservation fish hatcheries raise cod, salmon, trout and other types of fish and release them in places where their species may be threatened, or where their populations are declining.  

Astronomers have found a new way of measuring the spin in supermassive black holes. By viewing optical, ultra-violet and soft x-rays generated by heat as the black hole fed, they were able to measure how far the disc was from the black hole.