Monday, March 28, 2011

Saturday, March 12, 2011

Balance Sheet Recession

What is a balance sheet recession and is the US in one?
Richard Koo: How the West is Repeating Japan's Mistakes.

Friday, March 11, 2011

Argon on Venus

There is Too much argon 40 on the moon (a recent blog post) and argon in the atmosphere of Venus is hard to understand as well. In both lunar rocks and the atmosphere of Venus the Argon 40/argon 36 ratio is 1:1 while in the atmosphere of Earth argon 40 is 99.6%.

See also 40Ar retention in the terrestrial planets and Geochemistry: Earth holds its breath in Nature 2007.

Thursday, March 10, 2011

Star Clusters

Families of dynamically hot stellar systems over ten orders of magnitude in mass is a survey of star clusters in size from a few hundred to giant elliptical galaxies with a trillion stars.

Friday, March 04, 2011

Too much argon 40 on the moon

The decay of radioactive isotope potassium 40 to argon 40 is one of the main ways of finding the age of rocks: see Potassium-argon dating at Wikipedia.
But on the moon, the Apollo missions found much more argon 40 than could be explained by potassium decay. Other explanations don't look so great either, see: On the question of the 40Ar excess in lunar soils.

Globular clusters have little dark matter

Apparently globular clusters have little or no dark matter:
Evidence Against Dark Matter Halos Surrounding the Globular Clusters MGC1 and NGC 2419. This preprint also finds the motion of stars in these globular clusters is consistent with Newtonian gravity and not MOND, even though the clusters are in the low acceleration range in which MOND is supposed to make a difference. However previous see the blog post Velocities in Globular Clusters for a report that MOND does work in GCs!
Maybe globular clusters originated as the nuclear cluster of a galaxy: the preprint Nuclear Star Clusters mentions this as a possibility while discussing the star clusters at the center of galaxies.

In contrast Dwarf spheroidal galaxies are dark matter dominated.

Tuesday, March 01, 2011

The Missing Satellites Problem

The standard of model of the cosmology Lambda-CDM predicts that our Milky Way galaxy should have many more satellite galaxies than we actually see: Dwarf Galaxy Problem. It could be that some are actually missing or perhaps they are fainter than expected and hard to detect. See the preprints Notes on the Missing Satellites Problem for a review and also Too big to fail? The puzzling darkness of massive Milky Way subhalos.

Guarding the Germline

The great apes (humans, gorillas and chimps) are able to reproduce for many decades -longer than other primates. Researchers have discovered a genetic change which is active in human testis that helps guard the genome and ensure the quality of sperm. See the original report Endogenous retrovirus drives hitherto unknown proapoptotic p63 isoforms in the male germ line of humans and great apes in PNAS and Those retroviruses get everywhere at the MicrobiologyBytes blog.
It wasn't clear to me if this also occurs in Orangutans, the paper said the change occurred about 15 million years ago and the Orangutans diverged 12-16Mya Comparative and demographic analysis of orang-utan genomes. Female orangutans are fertile for 30 years, fairly similar to human females. What about the males?