Hasil untuk "physics.acc-ph"

L. Gerweck, K. Seetharaman

R. Bates

M. Wachstein, E. Meisel

D. Brookins

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.

M. Wedborg, D. Turner, L. Anderson et al.

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

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

M. Chesler

Chunyi Sun, C. Qin, Xinlong Wang 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

T. V. Gorlov, A. Aleksandrov, S. Cousineau et al.

The method of H- photoionization is interesting for laser assisted charge exchange injection. In this paper, the model and computation of photoionization of negative hydrogen ion by using strong lasers is considered. The development of this work is motivated by using pure lasers for photodetachment of electron from negative hydrogen ion when it is not convenient or not possible to use stripping magnet. Herein we develop a method of calculation of high efficiency photoionization using time dependent wave equation with application of powerful lasers. We compare this precise method of calculation with simplified method of calculation through linear model of cross section interaction. Another mechanism of photodetachment through excitation of the Feshbach resonance is also considered.

D. S. Bondar, V. I. Maslov, I. N. Onishchenko

The paper considers the excitation of a wakefield in a metal-density plasma using a chain of x-ray laser pulses. The profiling parameters and the necessary parameters of laser pulses for obtaining stable high-quality bunches are found. An essential problem is the destruction of self-injected bunches in the course of their motion. The results of the study are one of the ways to solve the problem of transverse betatron oscillations, which lead to the destruction of bunches.

R. A. Jameson, V. S. Skachkov

English translation of Russian book compiled to honor the memory of Ilya Mikhailovich Kapchinsky - To the 90th Birthday Collection of Memories. The idea for this publication belongs to Nikolai Vladimirovich Lazarev, a close collaborator of Ilya Mikhailovich Kapchinsky, head of one of the laboratories in the ITEP department that Kapchinsky headed. It was through the efforts of N.V. Lazarev that most of the materials in the collection were gathered. The main headings are: I. Little Known Heritage of I.M. Kapchinsky, II. Documents Joyful and Mournful, III. Memories of Family and Friends, Fragments of our life, IV. Memories of Colleagues of I.M. Kapchinsky, List of Scientific Papers, Afterword, Photos and Documents.

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

A. Bandodkar, V. Hung, W. Jia et al.

Omid Zandi, Renske M. van der Veen, Phil M. Duxbury et al.

In this letter, a phase transition of a non-equilibrated single component plasma evolving within a uniform constant magnetic field is demonstrated for the first time. We present classical fluid models that capture this phenomenon, confirm with N -particle simulations, derive constraints on parameters necessary to induce this phase transition, and suggest an experiment to test the novel predictions of the theory.