Ultimate causes of state formation: the significance of biogeography, diffusion, and neolithic revolutions

"The timing of early state formation varies across the world. Inspired by Jared Diamond's seminal work, the authors employ large-n statistics to demonstrate how this variation has been structured by prehistoric biogeographical conditions, which have influenced the timing of the transition from hunter/ gatherer production to agriculture and, in turn, the timing of state formation. Biogeography structures both the extent to which societies have invented agriculture and state technology de novo, and the extent to which these inventions have diffused from adjacent societies. Importantly, they demonstrate how these prehistoric processes have continued to shape state formation by influencing the relative competitiveness of states until the near present." (author's abstract

Erhvervslivets adgang til kollektiv transport

Der er stor forskel på, hvor ofte bussen eller toget gør stop ved erhvervsområder rundt om i landet. Nogle områder er betjent med en række bus- og/eller togforbindelser, mens andre har ganske få eller ingen daglige afgange i myldretiden på trods af, at der er mange ansatte og stor omsætning

Scale-free behaviour of amino acid pair interactions in folded proteins

The protein structure is a cumulative result of interactions between amino acid residues interacting with each other through space and/or chemical bonds. Despite the large number of high resolution protein structures, the "protein structure code" has not been fully identified. Our manuscript presents a novel approach to protein structure analysis in order to identify rules for spatial packing of amino acid pairs in proteins. We have investigated 8706 high resolution non-redundant protein chains and quantified amino acid pair interactions in terms of solvent accessibility, spatial and sequence distance, secondary structure, and sequence length. The number of pairs found in a particular environment is stored in a cell in an 8 dimensional data tensor. When plotting the cell population against the number of cells that have the same population size, a scale free organization is found. When analyzing which amino acid paired residues contributed to the cells with a population above 50, pairs of Ala, Ile, Leu and Val dominate the results. This result is statistically highly significant. We postulate that such pairs form "structural stability points" in the protein structure. Our data shows that they are in buried α-helices or β-strands, in a spatial distance of 3.8-4.3Å and in a sequence distance >4 residues. We speculate that the scale free organization of the amino acid pair interactions in the 8D protein structure combined with the clear dominance of pairs of Ala, Ile, Leu and Val is important for understanding the very nature of the protein structure formation. Our observations suggest that protein structures should be considered as having a higher dimensional organization

AID enzymatic activity is inversely proportional to the size of cytosine C5 orbital cloud

Activation induced deaminase (AID) deaminates cytosine to uracil, which is required for a functional humoral immune system. Previous work demonstrated, that AID also deaminates 5-methylcytosine (5 mC). Recently, a novel vertebrate modification (5-hydroxymethylcytosine - 5 hmC) has been implicated in functioning in epigenetic reprogramming, yet no molecular pathway explaining the removal of 5 hmC has been identified. AID has been suggested to deaminate 5 hmC, with the 5 hmU product being repaired by base excision repair pathways back to cytosine. Here we demonstrate that AID’s enzymatic activity is inversely proportional to the electron cloud size of C5-cytosine - H . F . methyl .. hydroxymethyl. This makes AID an unlikely candidate to be part of 5 hmC removal