Galaxies are the building blocks of the Universe. Each of them comprises some hundred billion radiant stars, such as our sun, which extend across about 50,000 light years. Every galaxy is embedded in a spherical halo made of dark matter that cannot be seen but is detected through its massive gravitational attraction. The exact nature of this matter is still unknown. 

Scientists have finally solved one of the major mysteries of star formation - how very massive stars form without blowing themselves apart in the process. According to star formation theory and previous simulations, the internal pressure created as a very massive star begins to shine should counteract the gravitational force pulling more material in, blowing away the outer layers of the star before it can get sufficiently massive.

Observations, however, show that stars exist with masses above the theoretical threshold and often coexist with other massive stars in binary systems - providing a mystery to astrophysicists until now.

A research team in Portugal and the US has found for the first time nicotine receptors in the taste buds. In fact, although most of the toxicity of smoking is linked to other components, it is nicotine that leads to smoking addiction and until now it was believed that this substance had to migrate into the brain to bind its specific receptors and provoke its effects.

People on low-carbohydrate diets are more dependent on the oxidation of fat in the liver for energy than those on a low-calorie diet, researchers at UT Southwestern Medical Center have found in a small clinical study published in Hepatology.

Although the study was not designed to determine which diet was more effective for losing weight, the average weight loss for the low-calorie dieters was about 5 pounds after two weeks, while the low-carbohydrate dieters lost about 9½ pounds on average. 

Glucose, a form of sugar, and fat are both sources of energy that are metabolized in the liver and used as energy in the body. Glucose can be formed from lactate, amino acids or glycerol. 

A new report, co-authored by a University of Hertfordshire academic, which will be launched this Thursday (22 January), has revealed that girls are more likely to have new technologies at home than boys and it is mothers rather than fathers who assist them.

The Learning in the Family report which looked at how families are involved in children’s learning, was funded by Becta, commissioned by Intuitive Media Research Services and co-authored by Robert Hart of Intuitive Media and Professor Karen Pine, at the University’s School of Psychology. They conducted two online surveys with a sample of 4,606 children aged six to fourteen, going into more depth with a further 2,535 children and then interviewed twelve families.

It has been difficult to prove that fast-swimming sperms have an advantage when it comes to fertilizing an egg but a research team at Uppsala University say that unfaithful females of the cichlid fish species do influence the males’ sperms - increased competition leads to both faster and larger sperms, and the research findings published in PNAS say that the much mythologized size factor does indeed count.

The findings also show that the speed and the size of sperms are closely related: larger sperms are faster. These sperms swim faster thanks to the greater power of a larger flagellum, but faster sperms also need to have a larger store of energy, which in turn results in larger sperms.

In terms of diversity and sheer numbers, the microbes occupying the human gut easily dwarf the billions of people inhabiting the Earth. Numbering in the tens of trillions and representing many thousands of distinct genetic families, this microbiome, as it's called, helps the body perform a variety of regulatory and digestive functions, many still poorly understood. 

How this microbial mélange may be linked to body weight changes associated with morbid obesity is a relevant and important clinical question that has received recent attention. Now, a new study suggests that the composition of microbes within the gut may hold a key to one cause of obesity—and the prospect of future treatment.

The cast of "House" won't need to find new jobs any time soon but using a robotic assistant to remove a patient's gallbladder by key-hole surgery (laparoscopic cholecystectomy) was as safe as working with a human assistant, a Cochrane Review has concluded. Comparisons between robot- and human-assisted surgery showed that there were no differences in terms of morbidity, the need to switch to open surgery, total operating time, or length of stay in hospital.

It's not quite a "Book of the Dead" but a 14th century brick oven uncovered by archaeologists in Spain found a unique  use for animal bones just the same - strengthening city fortifications.   The scientists report that the animal bones were burnt in the oven and mixed with other materials to produce a protective coating that strengthened the grand medieval walls of what is today Granada, Spain.  It must have worked pretty well since Granada and the surrounding territory were the last bastion of Islamic Iberia during that period.

In a study scheduled to appear in the Jan. 15 issue of Analytical Chemistry, scientists describe how they found these materials thanks to their new testing method.

Edward Larson, author of a Pulitzer Prize-winning history of the Scopes trial (which I highly recommend), writes in Bookforum about the influence of racism on Darwin's thinking. Creationists argue (as most recently exemplified in Ben Stein's widely panned film Expelled) that "practically all the harmful practices and deadly philosophies that plague mankind have their roots and pseudo-rationale in evolutionism." To these people, in this year of big Darwin bicentennial celebrations,  "all the hoopla must seem like throwing a birthday party for Hitler."