Group items tagged

Of the twenty amino acids used in proteins, ten were formed in Miller's atmospheric discharge experiments. The two other major proposed sources of prebiotic amino acid synthesis include formation in hydrothermal vents and delivery to Earth via meteorites. We combine observational and experimental data of amino acid frequencies formed by these diverse mechanisms and show that, regardless of the source, these ten early amino acids can be ranked in order of decreasing abundance in prebiotic contexts. This order can be predicted by thermodynamics. The relative abundances of the early amino acids were most likely reflected in the composition of the first proteins at the time the genetic code originated. The remaining amino acids were incorporated into proteins after pathways for their biochemical synthesis evolved. This is consistent with theories of the evolution of the genetic code by stepwise addition of new amino acids. These are hints that key aspects of early biochemistry may be universal.

We all are aware of the fact that billions of years ago, there was very little oxygen on Earth to breathe. Scientist of University of California at Riverside (UCR) have researched when in Earth's history oxygen may have abundant. Curious to know how origins of Earth survived?

We all are aware of the fact that billions of years ago, there was very little oxygen on Earth to breathe. Scientist of University of California at Riverside (UCR) have researched when in Earth's history oxygen may have abundant. Curious to know how origins of Earth survived?

We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that are consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying-alpha cosmologies is outlined in the light of all the observational constraints.

The Bolshoi simulation is the most accurate cosmological simulation of the evolution of the large-scale structure of the universe yet made ("bolshoi" is the Russian word for "great" or "grand").  The first two of a series of research papers describing Bolshoi and its implications have been accepted for publication in the Astrophysical Journal. The first data release of Bolshoi outputs, including output from Bolshoi and also the BigBolshoi or MultiDark simulation of a volume 64 times bigger than Bolshoi, has just been made publicly available to the world's astronomers and astrophysicists.