The intensity of earth's magnetic field has been weakening in the last couple of hundred years, leading some to claim that its polarity might be about to flip.

But the field's intensity is coming down from an abnormal high rather than approaching a reversal. And despite Doomsday prophecies stating otherwise, humans have lived through dips in the field's intensity before. Linking reversals in the more distant past to species extinctions is just speculation that can't be proved or disproved, which makes them ideal fodder for scary stories about nature.

A carbon tax of just $11 would offset the CO2 emissions from tourism, according to a paper in the Journal of Sustainable Tourism.

Every time people go on vacation, or journalists go off to climate conferences like the one in Paris, they are using fossil fuel energy. The total emissions from vacations like that would be the sixth largest emitter of CO2 if it were a country - five percent of total human-made emissions of CO2.   

The most direct information about the interior of the earth comes from measuring how seismic acoustic waves--such as those created by earthquakes -- travel through the earth. Those measurements show that 95% of the earth's core is liquid. But, scientists also want to know the composition of the liquid, and that is harder. Now, in research published in Nature Communications, scientists from the Materials Dynamics Laboratory at the RIKEN SPring-8 Center, along with collaborators from the Tokyo Institute of Technology's Earth-Life Science Institute and other institutes, have succeeded in measuring the speed of sound in mixtures of liquid iron and carbon in extreme conditions, allowing limits to be set on the core composition.

Researchers have attempted to measure all the material leaving and entering a mountain range over millions of years and discovered that glacial erosion can, under the right circumstances, wear down mountains faster than plate tectonics can build them.

A study of the St. Elias Mountains on the Alaskan coast by researchers from The University of Texas at Austin, University of Florida, Oregon State University and elsewhere found that erosion accelerated sharply about one million years ago.

Scientists have revealed that glucocorticoids, a class of steroid hormones that are commonly prescribed as drugs, enhance muscle endurance and alleviate muscular dystrophy through activation of the gene KLF15. Critically, this pathway is not involved in muscle wasting or the other major detrimental effects of prolonged steroid use.

The discovery could lead to the development of new medications that improve muscle function without the negative consequences caused by long-term steroid exposure, especially important for progressive muscle wasting diseases like Duchenne's muscular dystrophy (DMD).

The introduction of agriculture into Europe about 8,500 years ago changed the way people lived right down to their DNA.

Until recently, scientists could try to understand the way humans adapted genetically to changes that occurred thousands of years ago only by looking at DNA variation in today's populations. But our modern genomes contain mere echoes of the past that can't be connected to specific events.

Now, an international team reports in Nature that researchers can see how natural selection happened by analyzing ancient human DNA.

Engineers have developed a new technology that uses an oscillating electric field to easily and quickly isolate drug-delivery nanoparticles from blood. 

Nanoparticles are generally one thousand times smaller than the width of a human hair and are difficult to separate from plasma, the liquid component of blood, due to their small size and low density. Traditional methods to remove nanoparticles from plasma samples typically involve diluting the plasma, adding a high concentration sugar solution to the plasma and spinning it in a centrifuge, or attaching a targeting agent to the surface of the nanoparticles.

These methods either alter the normal behavior of the nanoparticles or cannot be applied to some of the most common nanoparticle types.

Migration between different communities of bacteria is the key to the type of gene transfer that can lead to the spread of traits such as antibiotic resistance, according to researchers. While horizontal gene transfer - also known as bacterial sex - has long been acknowledged as central to microbial evolution, why it is able to exert such a strong effect has remained a mystery. 

But now scientists at Oxford University have demonstrated through mathematical modelling that the secret is migration, whereby movement between communities of microbes greatly increases the chances of different species of bacteria being able to swap DNA and adopt new traits.

The study sheds new light on how the spread of traits such as antibiotic resistance is able to happen.