Measuring linear and non-linear galaxy bias using counts-in-cells in the Dark Energy Survey Science Verification data

Non-linear bias measurements require a great level of control of potential systematic effects in galaxy redshift surveys. Our goal is to demonstrate the viability of using counts-in-cells (CiC), a statistical measure of the galaxy distribution, as a competitive method to determine linear and higher-order galaxy bias and assess clustering systematics. We measure the galaxy bias by comparing the first four moments of the galaxy density distribution with those of the dark matter distribution. We use data from the MICE simulation to evaluate the performance of this method, and subsequently perform measurements on the public Science Verification data from the Dark Energy Survey. We find that the linear bias obtained with CiC is consistent with measurements of the bias performed using galaxy–galaxy clustering, galaxy–galaxy lensing, cosmic microwave background lensing, and shear + clustering measurements. Furthermore, we compute the projected (2D) non-linear bias using the expansion δg=∑3k=0(bk/k!)δk, finding a non-zero value for b2 at the 3σ level. We also check a non-local bias model and show that the linear bias measurements are robust to the addition of new parameters. We compare our 2D results to the 3D prediction and find compatibility in the large-scale regime (>30 h−1Mpc).ISSN:0035-8711ISSN:1365-296

ND3 Cys39 in complex I is exposed during mitochondrial respiration

Mammalian complex I can adopt catalytically active (A-) or deactive (D-) states. A defining feature of the reversible transition between these two defined states is thought to be exposure of the ND3 subunit Cys39 residue in the D-state and its occlusion in the A-state. As the catalytic A/D transition is important in health and disease, we set out to quantify it by measuring Cys39 exposure using isotopic labeling and mass spectrometry, in parallel with complex I NADH/CoQ oxidoreductase activity. To our surprise, we found significant Cys39 exposure during NADH/CoQ oxidoreductase activity. Furthermore, this activity was unaffected if Cys39 alkylation occurred during complex I-linked respiration. In contrast, alkylation of catalytically inactive complex I irreversibly blocked the reactivation of NADH/CoQ oxidoreductase activity by NADH. Thus, Cys39 of ND3 is exposed in complex I during mitochondrial respiration, with significant implications for our understanding of the A/D transition and the mechanism of complex I