Hasil untuk "physics.atom-ph"

K. Emerson, R. Russo, R. Lund et al.

L. Gerweck, K. Seetharaman

Guohua Chen, A. Hoffman

R. Bates

M. Wachstein, E. Meisel

M. Koivusalo, Christopher M. Welch, H. Hayashi et al.

Inhibitors of Na+/H+ exchange proteins block macropinocytosis by lowering the pH near the plasma membrane, which in turn inhibits actin remodeling by Rho family GTPases.

A. Gourine, V. Kasymov, N. Marina et al.

A. Savina, C. Jancic, S. Hugues et al.

James B. Gerken, J. G. McAlpin, Jamie Y. C. Chen et al.

Sung-Ching Chen, Yung-Chih Wu, F. Mi et al.

Chunyi Sun, C. Qin, Xinlong Wang et al.

M. McCulloch, J. Falter, J. Trotter et al.

Adam L. Hughes, D. Gottschling

Mitochondria have a central role in ageing. They are considered to be both a target of the ageing process and a contributor to it. Alterations in mitochondrial structure and function are evident during ageing in most eukaryotes, but how this occurs is poorly understood. Here we identify a functional link between the lysosome-like vacuole and mitochondria in Saccharomyces cerevisiae, and show that mitochondrial dysfunction in replicatively aged yeast arises from altered vacuolar pH. We found that vacuolar acidity declines during the early asymmetric divisions of a mother cell, and that preventing this decline suppresses mitochondrial dysfunction and extends lifespan. Surprisingly, changes in vacuolar pH do not limit mitochondrial function by disrupting vacuolar protein degradation, but rather by reducing pH-dependent amino acid storage in the vacuolar lumen. We also found that calorie restriction promotes lifespan extension at least in part by increasing vacuolar acidity via conserved nutrient-sensing pathways. Interestingly, although vacuolar acidity is reduced in aged mother cells, acidic vacuoles are regenerated in newborn daughters, coinciding with daughter cells having a renewed lifespan potential. Overall, our results identify vacuolar pH as a critical regulator of ageing and mitochondrial function, and outline a potentially conserved mechanism by which calorie restriction delays the ageing process. Because the functions of the vacuole are highly conserved throughout evolution, we propose that lysosomal pH may modulate mitochondrial function and lifespan in other eukaryotic cells.

J. Xiong, Yongqin Liu, Xiangui Lin et al.

Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4–1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r = 0.443, P = 0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments.

G. Jeppu, T. Clement

Anthony M. Polloreno, Graeme Smith

Broadband detection of a weak oscillatory field with unknown carrier frequency underlies magnetometry, axion searches and gravitational-wave sensing. We show that the Grover-like integration-time lower bound for this task is a geometric corollary an upper bound on the integrated quantum Fisher information, a metrological constraint. We further give an all-analog multi-resonant protocol based on a randomized Su-Schrieffer-Heeger control Hamiltonian and an m-register GHZ probe and verify near-optimal scaling through simulation.

Alexander Petrov

RaOCH$_3$ molecule is one of the most sensitive systems for the electron electric dipole moment ($e$EDM) searches. Its hyperfine and $K-$doubling structure in the external electric field is of key importance for preparing and interpreting the experiment. We propose the method for calculation the symmetric top molecules and applied it for RaOCH$_3$. Hyperfine structure, $K-$doubling and sensitivity of the molecule to $e$EDM in the external electric field were calculated.

Sijie Chen, Yuning Hong, Yang Liu et al.

Takayuki Yoshida, T. C. Lai, G. Kwon et al.

Andrzej Czarnecki

Probability of finding negative energy states in a hydrogen atom is decreased when the nucleus is extended. Reduced electron Compton wavelength is the characteristic size of the region around the nucleus where negative energy contributions to the wave function are sizeable.